Foretravel Motorhome Forums => Foretravel Tech Talk => Topic started by: Caflashbob on February 14, 2014, 03:05:12 am
Title: Battery usage percentages
Post by: Caflashbob on February 14, 2014, 03:05:12 am
Spent some time reading the link 2000 owners manual. It mentions a 50% discharge not a problem before recharging. And that 85% of measured capacity is ok. Their book then mentions that the 35% remaining should be a good working range for a battery system.
In my case with three 8g8d's the nominal capacity is 675 amp hours(not measured yet) and that means I can run between -100 amp hours and -338 amp hours and be safe and not effect the batteries life.
I normally run the gen after overnight use of 100-125 amp hours but the link book seems to say I could run two or more days before recharging. My small solar may add 40-50 amp hours a day.
Be nice to not listen to the gen other than convection oven times or washer/dryer or long microwave times.
My data in the memory of the link shows a max of -338 amp hours at some time since the batteries were installed but my tech buddy might have tested them down that far. I do not remember this myself.
Anyone tried using the MK gels to these levels and live to tell about it?
At -125 amp,hours I am still at 12.6 volts....
Trying to learn the coaches capacities.....
Most seem to be like me and recharge them totally every discharge. Accept starts at around -40 amp hours
Bob
Title: Re: Battery usage percentages
Post by: bbeane on February 14, 2014, 06:31:29 am
Bob, if we are dry camping I will let mine go to 12.2V at no load before recharge, that takes a good while using just lights ,fridge on gas and TV. I do try to avoid large loads on the battery's by running the generator in the mornings for coffee, and microwave use to avoid the large loads on the inverter and battery's. I can usually go a couple of days without much generator run time, I also keep the inverter off when not in use the older ones have a pretty large stand by draw on them. However when I do run the generator to recharge, I let it go until the batteries are fully charged. Most of the time the generator is on auto start even when plugged in at the house. My shoreline 8D's are 9 years old (knock on wood) and still going strong. We don't do alot of dry camping so the battery bank doesn't get a lot of work out. No mater what any battery only has so many discharge cycles in it, the more you use them the shorter the life will be.
Title: Re: Battery usage percentages
Post by: fouroureye on February 14, 2014, 08:07:07 am
Discharge cycles? :-\
Thought they decreased the deeper the discharge? So in turn increase the less the discharge.
Wyatt - from what I have read here is the "Master Jedi" when it comes to batteries. Perhaps he will help us understand it better. :help: :help:
Title: Re: Battery usage percentages
Post by: amos.harrison on February 14, 2014, 08:36:06 am
I follow the same practices as Bruce.
Title: Re: Battery usage percentages
Post by: wolfe10 on February 14, 2014, 08:39:09 am
And, while 50/85 is OK, at least once a week, the batteries need to be brought to 100% to retain full capacity.
Title: Re: Battery usage percentages
Post by: Caflashbob on February 14, 2014, 11:48:50 am
This morning am at -180 amp hours and 12.4 at the link 2000. The actual batteries are probably slightly higher due to voltage drop in the cabling to the panel as my guru mentioned.
Still versus starting the gen much more I am not as worried about it now.
The solar panel at 7.9 amps input will easily recharge the coach over a week even down this much fine.
Lots to learn everyday it seems.
Bob
Title: Re: Battery usage percentages
Post by: wolfe10 on February 14, 2014, 12:18:24 pm
Bob,
When we are talking about voltage at 50% discharge, we are talking about having the batteries AT REST. No charging and no discharging for at least an hour.
If under load, voltage readings will be lower (which is acceptable).
The link system should give you a pretty good indication of amp-hr use. It needs to be reset occasionally.
Title: Re: Battery usage percentages
Post by: J. D. Stevens on February 14, 2014, 01:17:38 pm
The link system should give you a pretty good indication of amp-hr use. It needs to be reset occasionally.
We have the Link 2000 on our OEM Freedom 25 (vintage 1996-97). If the batteries charge long enough that the Amp-Hour meter goes to a positive value, it will reset to zero when the batteries start discharging. I just tested the function by turning of the charger and turning on a few lights. Indeed, the A-H meter went from a positive value to 0 and began counting A-H used since full charge.
I was using about 100 A-H per day according to the Link 2000. I did run the furnaces at night to keep the coach at about 70F. We have one solar panel that appears to be OEM.
Batteries are Power House brand (? manufacture) dated 2008. They worked fine until this week. One apparently shorted a cell and started outgassing. Another feels warmer to the touch than does the other remaining functional battery. I plan to replace all three in March. Probably will get them at A&D Hydraulics in NAC.
Title: Re: Battery usage percentages
Post by: John S on February 14, 2014, 02:54:15 pm
Buy them outside of Nac. Much cheaper that way. I just had them install the three batteries. I bought three new ones in April for about 350 a piece and I bought one in Nac and it was just over 700.
Title: Re: Battery usage percentages
Post by: J. D. Stevens on February 15, 2014, 04:37:52 pm
Buy them outside of Nac. Much cheaper that way. I just had them install the three batteries. I bought three new ones in April for about 350 a piece and I bought one in Nac and it was just over 700.
Because of your suggestion, I am rethinking the issue. It appears that I can get Lifeline GPL-8DA for $619 each at a distributor about 80 miles from home. I'm sure I can find cheaper batteries, but my impression from other people's posts is that you get some additional value for the additional cost of the Lifeline batteries.
The big challenge may be to install them. The house batteries in our coach are on shelves that roll out a bit. I'll probably still need to get some help to lift the 160# batteries. (I have mentored one student from 4th grade to 11th grade. It may be time to see how strong he is now. :P )
A second battery failed. It was running warm and the current was much too high after plenty of time to enter float mode. I pulled the negative cable on the hot battery. With the charger turned off, the voltage at the Link 2000 rose after removing the offending battery. The remaining battery appears to be floating properly.
Title: Re: Battery usage percentages
Post by: John Haygarth on February 15, 2014, 04:53:15 pm
JD, thast is a good price for Lifelines as here they are over 800. I bought mine 3 yrs ago for 499 at AMsolar so they sure have gone up. I would not change them as I feel they are a good battery. John H
Title: Re: Battery usage percentages
Post by: Tim Fiedler on February 15, 2014, 04:53:31 pm
Wonder if your charger is cooking your batteries
Title: Re: Battery usage percentages
Post by: Barry & Cindy on February 15, 2014, 05:43:38 pm
When we looked a Lifelines, we found the top wider, which would be fit problem in our battery tray. Too much passion on what battery to use, but we think East Penn are very good and they have the same 8D8G size in GEL & AGM. East Penn are widely available in auto store labels and also MK brand. We think GEL can take more abuse and last longer. We think AGM can be charged at higher voltages, probably speeding up charge time. We think Lifeline is over marketed & hyped, but work as well as other AGMs.
Title: Re: Battery usage percentages
Post by: Caflashbob on February 15, 2014, 06:22:21 pm
A second battery failed. It was running warm and the current was much too high after plenty of time to enter float mode. I pulled the negative cable on the hot battery. With the charger turned off, the voltage at the Link 2000 rose after removing the offending battery. The remaining battery appears to be floating properly.
Extremely large chance of continuing problems if all the batteries in a system are not the exact same condition. All new together unfortunately. We have all tried replacing parts of a matched system with poor results.
Bob
Title: Re: Battery usage percentages
Post by: wolfe10 on February 15, 2014, 06:29:28 pm
Perhaps a little more information is in order.
What can happen when you have a weak battery/dead cell connected in parallel with a good battery/all good cells is this:
The charger senses the low voltage caused by the dead cell (if one cell of a 12 VDC battery is dead, it is now a 10 VDC battery being charged as if it were a 12 VDC battery). This SEVERELY overcharges the remaining cells, causing overheating/boiling of electrolyte.
Worse, the good battery gets this excessive charge as the charger tries to charge that 10 VDC battery at 13+ VDC, taking it out as well.
Title: Re: Battery usage percentages
Post by: John S on February 15, 2014, 06:41:05 pm
I went with eastern penn gels too. They are cheaper and they lasted 7 years without a problem. I just changed them every 6 to 7 years no matter the charge as they do not hold as much as when they are new. The grandvention had a good seminar on how batteries are made and how they die too.
Title: Re: Battery usage percentages
Post by: Caflashbob on February 15, 2014, 06:44:50 pm
What can happen when you have a weak battery/dead cell connected in parallel with a good battery/all good cells is this:
The charger senses the low voltage caused by the dead cell (if one cell of a 12 VDC battery is dead, it is now a 10 VDC battery being charged as if it were a 12 VDC battery). This SEVERELY overcharges the remaining cells, causing overheating/boiling of electrolyte.
Worse, the good battery gets this excessive charge as the charger tries to charge that 10 VDC battery at 13+ VDC, taking it out as well.
I had noticeable problems with non dead cell similar batteries that were not similar dates and use. cut my losses as a Foretravel manager and replaced all the batteries in every used coach I resold. If plugged in to a pedestal all the time not as noticeable but dry camping was different
Bob
Title: Re: Battery usage percentages
Post by: J. D. Stevens on February 15, 2014, 10:45:02 pm
Thanks for all the good response regarding my issues as an extension of the topic of battery usage percentages.
We could be cooking the batteries, but I am guessing that I experienced failures related to: 1) six year old "no name" batteries; probably reasonably good life span; 2) a recent trip with more boon docking days than normal for us; 3) a significant failure in one battery added stress to the others and one of them failed.
I watch voltage, current, and AH draws carefully. Values have all been in reasonable range until very recently. It's time to change house batteries and verify that charging/maintenance values correspond to recommendations for the batteries we install.
Like so many issues, we'll find a solution and move on. We'll get some insight on whether it was a good solution after we use it in our life style for a while.
Title: Re: Battery usage percentages
Post by: RRadio on February 16, 2014, 01:51:39 pm
The scenario Brett described is probably what happened to my batteries. As soon as you notice a dead cell in one of your batteries disconnect the bad battery from the good battery immediately and you might be okay with the one good battery. If you leave the bad battery connected in parallel with the good battery you'll have two bad batteries in a very short time. I noticed last winter that one of my battery cells had probably shorted out slightly as the metal plates contracted with the temperature change. As soon as the weather warmed up the metal plates expanded and worked fine through the summer. The first time it got cold this winter it shorted out again and killed both batteries. If I had disconnected the bad battery immediately and sold it for scrap at a metal salvage yard I probably could have done just fine with one house battery... but instead it became one of life's little lessons :-(
Title: Re: Battery usage percentages
Post by: Tom Lang on February 17, 2014, 02:12:57 am
Five years ago, one of my three Optima starting batteries developed a shorted cell. I disconnected the bad battery and got along fine with only two batteries for a few weeks. I then replaced the bad battery with a newish blue top, and have been doing fine ever since. I suspect my eleven year old batteries will be in need of replacement soon, but they have had a good long life.
Title: Re: Battery usage percentages
Post by: RRadio on February 21, 2014, 11:30:08 am
Parts Plus sold me a pair of ordinary lead acid 8D batteries made by East Penn rated at 1100 CCA with 325 reserve capacity for $144.10 each plus tax. There was a $64 core charge for my old batteries. I can buy several sets of ordinary lead acid batteries over the years for the price of one set of AGM or gel type batteries. Ordinary lead acid batteries provide more than half the reserve capacity for much MUCH less than half the price. If I ever get a bad cell again that kills both batteries in parallel I'll be out much less money with lead acid batteries. Apparently all 8D lead acid batteries are deep cycle batteries regardless if they're labeled as cranking batteries or not, so don't spend extra for a deep cycle 8D... Just thought I'd be the voice of the cheapskate here on this forum. ;D
Title: Re: Battery usage percentages
Post by: Caflashbob on February 21, 2014, 11:42:56 am
Parts Plus sold me a pair of ordinary lead acid 8D batteries made by East Penn rated at 1100 CCA with 325 reserve capacity for $144.10 each plus tax. There was a $64 core charge for my old batteries. I can buy several sets of ordinary lead acid batteries over the years for the price of one set of AGM or gel type batteries. Ordinary lead acid batteries provide more than half the reserve capacity for much MUCH less than half the price. If I ever get a bad cell again that kills both batteries in parallel I'll be out much less money with lead acid batteries. Apparently all 8D lead acid batteries are deep cycle batteries regardless if they're labeled as cranking batteries or not, so don't spend extra for a deep cycle 8D... Just thought I'd be the voice of the cheapskate here on this forum. ;D
Monthly equalization if using them regularly, hard to access the cells mounted to check and add water, the need for battery heaters if going to cold weather, the lack of amps at very cold temperatures, compartment ventilation requirements from the hydrogen gas venting that occurs and I think a lower recharge rate on bulk recharge input are the other side to the less expensive. The gels can be airplane shipped as intrinsically safe. And mounted if memory serves me correctly in non horizontal mounts?
The gels I think have a higher internal normal voltage? Maybe?
Versus good to -76 degrees and never looking at them?
Good points although. I did replace the batteries in the coaches I sold with new lead acid twenty five years ago as the price was more reasonable.
Technology marches on.....
Title: Re: Battery usage percentages
Post by: Pierce & Gaylie Stewart on February 21, 2014, 07:12:45 pm
A fully charged battery won't freeze until temp dips below -70F and will retain a charge all winter unless connected to the coach with parasitic accessory loss. Battery will lose about 33% cranking power below freezing and more as the temp drops so a battery warmer would allow the battery to produce more CCA at lower temps.
My opinion is lead acid batteries are by far the least expensive for start batteries and last a long time. $300 or so for all three won't break the bank. Four years later they still crank just as well as when they were new even in very low temps. Trojans worked well for house in the old rig.
Pierce
Title: Re: Battery usage percentages
Post by: P. Wyatt Sabourin on February 21, 2014, 08:01:41 pm
I just saw this thread from a week ago.
So the real answer is that any battery is just an chemical/electrical device, which, like a tire, does not have an infinite life. If abused, the useable life of a battery can be as little as one year.
Recharge your batteries to 100% every day to maximize life.
Use a passive desulfator ($25) on each battery to maximize life. Equalizing (controlled over charge) every month will desulfate also but with shorter battery life.
Reset your charge voltage set points after 5 months of desulfation (for an 8D battery) to 0.2 volts higher. The accept voltage for my Gel is 14.4 volts (manufacturer says 14.2 volt), for my AGMs is 14.6 volts (manufacturer says 14.4). For flooded batteries reset accept to 14.9 volts.
Discharge your batteries no more then 80% most days to maximize life. Never go below 50%, even if the manufacturer claims that is OK. They are in the business for manufacturing and selling batteries - they want you to replace every 5 or 6 years.
I determined the accept voltages by watching my solar controller panel to see when it changed from bulk to accept and from accept to float. I also used the numbers from the amphour meters to determine the % of charge. Blue Sky Solar recommends using bulk up to 70% charged, absorption for 70% to 95% charged and float above 95% charged. The voltages quoted above resulted in following Blue Sky's recommendations. Lower voltages on desulfated batteries resulted in undercharging and being on float for hours.
The cycle king is a Gel battery, which can provide 2000 or more cycles over it's lifetime. Manufacturers may claim their AGM or wet cell batteries can get as many cycles as a Gel but I do not believe that based on the research that I have done.
I have an 11 year old Gel battery which still has a capacity of 150 amphours measured with a ten hour 10 amp test (2013 Nov). The original capacity claimed by the manufacturer was 220 amphours. I have cycled this battery about 200 times per year since 2006 (I am seldom in a campground when in California). I estimate it has been cycled about 2000 times; down to 70% (180 amphours used) about 100 times, to 80% about 500 times and down to 90% about 1400 times.
What is battery abuse? I have a friend who asked me about tree years ago to check her one year old Trojan golf cart batteries (four of them) because the automatic outdoor light I had installed was glowing red, which meant low voltage. Low voltage was confirmed and running the generator to recharge resulted in the battery charger going into float mode in only a few minutes. Turning just interior lights on for a few minutes and the red "low voltage" led turned on. Her batteries were badly sulfated because they were only partially charged for the entire year she had them because she would fall asleep reading using two 20 watt halogen bulbs (3.5 amps for 9 hours = 30 amphours). She did this several days each week. Her solar panels were not tipped up and they were never cleaned. She did not have an amphour meter, and the silly led battery condition panel never showed anything but green or yellow. Her batteries were probably never more then 50% charged for the entire year - this is what I refer to as battery abuse.
Generator charging vs. maximum life: Not possible unless you run your generator for 5 or more hours each day. This is because of the nature of batteries. It is not possible to rapid charge a battery past 70% charged. Attempting this (ie Equalizing for hours) will result in a battery with bulging sides/top due to heat or an exploded battery. If you charge your batteries using a generator, you are probably charging your batteries to only 85%, and like Brett said that is OK, just be aware that you will probably have to replace your batteries every 6 or 7 years
Can you tell the state of charge of your batteries using just voltage? The answer is "NO". Get an amphour meter to monitor your batteries - I have three, one on each battery (Thanks to Barry L.). Voltage alone is not accurate. To prove this to yourself do the following: 1. measure the voltage of one of your batteries. 2. Disconnect it from the bank and measure the voltage again in 3 hours. 3. Connect a lightbulb to the battery (1 or 2 amp, ie 1004, 1141, not an LED). 4. Measure the voltage every ten minutes for one hour. 5. Disconnect the bulb and measure the voltage every ten minutes for one hour. 6. Leave the battery disconnected and measure the voltage in three hours. 7. Report back to me. (just joking)
Caflashbob: I doubt that the amperage drawn on your Link 2000 for voltage measuring is sufficient to make the reading different than the actual battery voltage.
John S: What batteries did you buy for $350.
I bought Lifeline AGM 8D batteries from the distributor in northern LA for $425 cash in 2010 May. Seems that I got an amazing deal.
Flooded vs. sealed (AGM or Gel): I used flooded batteries many years ago, but found that the corrosion caused by the gases required a total cleanup of the wiring three times per year. Way too much work if you cycle your batteries 200 time a year as I do. If you only boondock occasionally - save the money, buy flooded golf cart batteries.
Caflashbob: Gel batteries do have a higher fully charged voltage than flooded batteries because they have lower internal resistance, but they do not stand up to abuse as well as flooded batteries. My Gel battery was 12.8 volts before desulfation and is now 13.1 volts when fully charged.
Title: Re: Battery usage percentages
Post by: John S on February 21, 2014, 08:48:28 pm
I bought 225 amp hour gell cell batteries. They are 476 a battery now but you also get about 100 bucks a battery for the old ones. So now it is 376 a battery. They are the same batteries you can get at A & D for 700.
Title: Re: Battery usage percentages
Post by: John S on February 21, 2014, 08:50:05 pm
Oh I did ask why so different and in Nac they sell a lot of batteries and the price seems to be a captive price and the transportation cost to get the batteries is more.
Title: Re: Battery usage percentages
Post by: Caflashbob on February 21, 2014, 09:20:27 pm
So the real answer is that any battery is just an chemical/electrical device, which, like a tire, does not have an infinite life. If abused, the useable life of a battery can be as little as one year.
Recharge your batteries to 100% every day to maximize life.
Use a passive desulfator ($25) on each battery to maximize life. Equalizing (controlled over charge) every month will desulfate also but with shorter battery life.
Reset your charge voltage set points after 5 months of desulfation (for an 8D battery) to 0.2 volts higher. The accept voltage for my Gel is 14.4 volts (manufacturer says 14.2 volt), for my AGMs is 14.6 volts (manufacturer says 14.4). For flooded batteries reset accept to 14.9 volts.
Thanks I figured you would comment. The desulfation you mention is the passive one?
So reset my charger to run to 14.4 instead of the 14.2....three new mk 8g8d's recently installed.
Set my small 130 watt solar setup the same?
Why is the 14.2 too low?
Thanks
Bob
Title: Re: Battery usage percentages
Post by: Brad & Christine Slaughter on February 21, 2014, 09:33:15 pm
I bought 225 amp hour gell cell batteries. They are 476 a battery now but you also get about 100 bucks a battery for the old ones. So now it is 376 a battery. They are the same batteries you can get at A & D for 700.
Where did you find this $476/$376 price, John? I haven't been able to find anything anywhere near that low online. I just got my Tri-metric installed, so I'm not yet too sure of my battery status, but they are getting a bit aged and I'd like to have a replacement plan.
Title: Re: Battery usage percentages
Post by: Dave M (RIP) on February 21, 2014, 09:51:08 pm
Wyatt, Wondering why the 14.4 on yur gel battery? and are you recommending equlizing the gel battery, and if so, at what voltage and for how long ?
I tend to think the factory has a good grasp on their product, but maybe there is reason to disreguard the factory recommendations ? After all, they are in business to sell batteries.
Also at the Grand vention in Tenn, the East Pen rep, claims to never heard of the desulfating on batteries, again, they are in business to sell their product. Dave M
Title: Re: Battery usage percentages
Post by: Pierce & Gaylie Stewart on February 21, 2014, 10:44:16 pm
Have seen hopelessly dead, dead, dead batteries brought back to life with a desulfator. Does not work with batteries at the end of their life but fairly new batteries that have been allowed to go flat for some reason and a regular battery charger won't do the trick. See at: Battery Desulphator Desulfator DUAL Pulse 4 Lead Battry | eBay (http://www.ebay.com/sch/sis.html?_kw=Battery+Desulphator+Desulfator+DUAL+Pulse+4+Lead+Battry)
Pierce
Title: Re: Battery usage percentages
Post by: Tom Lang on February 22, 2014, 12:31:35 am
After doing some thinking, asking questions, and reading tech docs, I now have a plan for my own boondocking.
The plan is to get my trimetric 2020 connected, install about 270 watts of solar, and run my generator each morning until the charge current begins to drop from it's 103 Amp bulk. This should bring my new AGMs up to 75% full charge. Then, hopefully, the solar charging all day will bring them up to 100%.
If that isn't enough solar to reach 100%, my options are to add more solar or run the generator until the charge rate drops to 50A.
What I learned with my week at Quartzite is that my usage without solar required 3-4 hours of generator charging at mostly 100A to keep the batteries in the 50%-75% charge range, and I need to reach 100% occasionally for battery health.
Title: Re: Battery usage percentages
Post by: Tom Lang on February 22, 2014, 12:44:04 am
I know, the math doesn't quite add up.
If I put 300 A-H in to bring the charge from 50% to 75%, I'll need another 300 A-H to reach 100%. This would need 13 hours of full sun and 100% efficiency. My fudge factor is that I was probably closer to 60% min, and the trimetric will tell the truth. I can also do more to reduce power consumption.
Mygoal is to be kind to the batteries by bringing them all the way to 100% without running the generator day and night.
Title: Re: Battery usage percentages
Post by: Caflashbob on February 22, 2014, 12:45:51 am
After doing some thinking, asking questions, and reading tech docs, I now have a plan for my own boondocking.
The plan is to get my trimetric 2020 connected, install about 270 watts of solar, and run my generator each morning until the charge current begins to drop from it's 103 Amp bulk. This should bring my new AGMs up to 75% full charge. Then, hopefully, the solar charging all day will bring them up to 100%.
If that isn't enough solar to reach 100%, my options are to add more solar or run the generator until the charge rate drops to 50A.
What I learned with my week at Quartzite is that my usage without solar required 3-4 hours of generator charging at mostly 100A to keep the batteries in the 50%-75% charge range, and I need to reach 100% occasionally for battery health.
My observations are along your lines. My parasitic loses are less I think than most here so the amp hour use is less to start with. Do you have a residential refer?
I use about 100 amp hours in twelve hours overnight running mostly the aqua hot. Small inverter loads otherwise.
My old freedom 25 is not as efficient as the full wave newer unit but the loads are less.
The 270 might be enough but probably not versus no gen run time at least for me.
540 watts I think would be enough without a house refer for us....
Three times faster than what I have currently seems enough.
Title: Re: Battery usage percentages
Post by: Tom Lang on February 22, 2014, 12:52:31 am
My refrigerator is propane, so battery usage is minimal.
My main power hog was running both propane furnaces, but that was unavoidable.
Quartzite this year was a worst case test. I usually wouldn't have so much furnace run time.
Title: Re: Battery usage percentages
Post by: Caflashbob on February 22, 2014, 12:58:57 am
My refrigerator is propane, so battery usage is minimal.
My main power hog was running both propane furnaces, but that was unavoidable.
Quartzite this year was a worst case test. I usually wouldn't have so much furnace run time.
How many amp hours roughly overnight? Trying to compare the aqua hots usage at maybe high 40's at night versus the same weather and the propane furnaces.
Bob
Title: Re: Battery usage percentages
Post by: J. D. Stevens on February 22, 2014, 10:04:28 am
My refrigerator is propane, so battery usage is minimal.
My main power hog was running both propane furnaces, but that was unavoidable.
Quartzite this year was a worst case test. I usually wouldn't have so much furnace run time.
You can avoid running the furnaces if you don't mind being uncomfortable. :P I didn't buy DP to be uncomfortable. ;)
Quartzsite was my first time spending several days without hookups while staying in one place. I left the thermostat settings for the propane furnaces about 70F all the time. I kept the inverter off unless it was required. I ran the generator for 2-3 hours per day, usually in the morning because I use 120VAC electric appliances then. According to the Link 2000, I was using about 100-120 AH between generator runs.
I do have one small solar panel that is hard wired to the 12 VDC supply to the refrigerator. I expect that it contributes little to electric power system.
Title: Re: Battery usage percentages
Post by: P. Wyatt Sabourin on February 22, 2014, 10:56:50 am
Caflashbob: I recommend passive low power desulfators on each battery with leads as short as possible. The reasons are the price and the minimum interference caused for your 12 volt appliances. A desulfator generates a 1 kilohertz signal, a thousand 50 volt 6 amp spikes per second of very short duration. This spike forces sulfate back into solution and off the plates. Low power and short wires means little of this spike reaches the sensitive 12 volt items like fridge controller, AM/FM sterio. High power desulfators are available at much higher cost which will desulfate an entire battery bank, however, the power line to your 12 volt panel must be filtered so the 1 kilohertz signal does not interfere with your 12 volt items.
Do not reset your accept charge voltage until your batteries have been desulfated for several weeks. The safest way to do this is to disconnect a battery and let it sit overnight when it is fully charged. Measure the voltage in the morning to determine how much the desulfation has raised the fully charged voltage, then increase the accept voltage (for charger, alternator, solar controller) by this measured voltage increase.
With only 130 watts of solar, the maximum amps available is 8 and the number of amps you will actually see will be 2amp to about 5 or 6 amps. You could safely connect this to a 600 amphour battery bank without a controller.
The reason that 14.2 volts is too low for a desulfated Gel battery is that the fully charged voltage of a desulfated Gel is 13.0 or 13.1 volts when the manufacturer expects his battery to have a fully charged voltage of 12.8 volts. Charge voltage of 14.2 with fully charged voltage of 12.8 means the charge voltage is 1.4 volts higher then the fully charged voltage. Increasing the charge voltage to 14.4 maintains this 1.4 volt difference.
Title: Re: Battery usage percentages
Post by: P. Wyatt Sabourin on February 22, 2014, 11:01:20 am
There are some more great questions below which I will respond to later (got an appointment). Meanwhile, think about what effect the reduced recharge efficiency which happens as a battery approaches fully charged. Charging a battery from 50% to 60% is circa 80% efficient, however, changing a battery from 95% to 100% is only 50% efficient.
Title: Re: Battery usage percentages
Post by: Pierce & Gaylie Stewart on February 22, 2014, 11:08:40 am
In Quartzsite, we got a chance to test our solar setup in real world conditions. With 1140 watt potential, the panels installed flat and a low winter sun, we saw a maximum of 580 watts peak. Never had to start the generator and the batteries were "full" by noon with the controller switching to "float". Days that were cloudy took longer to reach float.
We did sit around the fire telling stories so our usage was less than it would have been if we had been by ourselves plus the winter weather was very agreeable so less time spent inside.
We have almost all LED lighting but do have a 42 inch LED/LCD TV, satellite receiver and Dish Tailgater that saw a lot of usage. With the microwave in operation, the Midnight controller battery voltage dropped during operation but quickly recovered.
Here is a good chart from Northern Arizona Wind & Sun with life expectancy of different types of batteries:
"These are some typical (minimum - maximum) typical expectations for batteries if used in deep cycle service. There are so many variables, such as depth of discharge, maintenance, temperature, how often and how deep cycled, etc. that it is almost impossible to give a fixed number.
Starting: 3-12 months Marine: 1-6 years Golf cart: 2-7 years AGM deep cycle: 4-8 years Gelled deep cycle: 2-5 years Deep cycle (L-16 type etc): 4-8 years Rolls-Surrette premium deep cycle: 7-15 years Industrial deep cycle (Crown and Rolls 4KS series): 10-20+ years. Telephone (float): 2-20 years. These are usually special purpose "float service", but often appear on the surplus market as "deep cycle". They can vary considerably, depending on age, usage, care, and type. NiFe (alkaline): 5-35 years NiCad: 1-20 years"
Pierce
Title: Re: Battery usage percentages
Post by: Paul Smith on February 22, 2014, 12:22:38 pm
That's curious, Pierce.
We were at Q, too. We have 1200 watts on top. Also flat.
And regularly saw 2KW.
I wonder what's going on?
best, paul
Quote
In Quartzsite, we got a chance to test our solar setup in real world conditions. With 1140 watt potential, the panels installed flat and a low winter sun, we saw a maximum of 580 watts peak. Never had to start the generator and the batteries were "full" by noon with the controller switching to "float". Days that were cloudy took longer to reach float.
Title: Re: Battery usage percentages
Post by: Caflashbob on February 22, 2014, 12:43:01 pm
Caflashbob: I recommend passive low power desulfators on each battery with leads as short as possible. The reasons are the price and the minimum interference caused for your 12 volt appliances. A desulfator generates a 1 kilohertz signal, a thousand 50 volt 6 amp spikes per second of very short duration. This spike forces sulfate back into solution and off the plates. Low power and short wires means little of this spike reaches the sensitive 12 volt items like fridge controller, AM/FM sterio. High power desulfators are available at much higher cost which will desulfate an entire battery bank, however, the power line to your 12 volt panel must be filtered so the 1 kilohertz signal does not interfere with your 12 volt items.
Do not reset your accept charge voltage until your batteries have been desulfated for several weeks. The safest way to do this is to disconnect a battery and let it sit overnight when it is fully charged. Measure the voltage in the morning to determine how much the desulfation has raised the fully charged voltage, then increase the accept voltage (for charger, alternator, solar controller) by this measured voltage increase.
With only 130 watts of solar, the maximum amps available is 8 and the number of amps you will actually see will be 2amp to about 5 or 6 amps. You could safely connect this to a 600 amphour battery bank without a controller.
The reason that 14.2 volts is too low for a desulfated Gel battery is that the fully charged voltage of a desulfated Gel is 13.0 or 13.1 volts when the manufacturer expects his battery to have a fully charged voltage of 12.8 volts. Charge voltage of 14.2 with fully charged voltage of 12.8 means the charge voltage is 1.4 volts higher then the fully charged voltage. Increasing the charge voltage to 14.4 maintains this 1.4 volt difference.
The solar panels controller SAYS 7.5 during the peak time. small wires although from the panel to the refer where for a simple installation my mechanic tapped into the 12 volt there. And the controller panel is after that installed below the refer.
I straddled the three MK 8g8d's with a passive desulfator when I installed the new batteries. Two months ago? So I should remove the cabling and seperate the three batteries and let them rest overnight then check the individual voltage?
If they are at 13.0 to 13.1 then I can turn up the alternator and the charger to the 14.4?
There are people who say they know and then a few who do know and have tested their knowledge.
Thanks for the help.
What capacity and brand of solar and controller should I look at to replace my 130 watt system?
Overnight use in high 40's overnight temps using the aqua hot never exceeds 120 amp hours.
Have three old inverters I came across and unfortunately all three at modified wave.
A 2022 "458" 2000 watt. A heart freedom 25 like my current unit and a trace 3012 with a rare remote panel.
They are are the inverter "doctor" a local guy in Costa Mesa, ca that had racks of refurbished ones and an scope to check them.
Not sure of the full wave added efficiency being worth replacing a functioning modified wave?
The relays in mine were not used as Foretravel used an external ATS that my buddy wired around to use the hearts internal one instead. So mechanically its good.
Not a lot of TV use.
Bob
Title: Re: Battery usage percentages
Post by: Pierce & Gaylie Stewart on February 22, 2014, 01:11:19 pm
Paul,
Got 2.5Kw on a day we used the most juice. If we had used more the night before, the total would have been higher. The 580 watts was not a total, just what the charge rate was at that moment. Starts off at 5 or 6 watts as the sun is rising and about half showing over the horizon. Goes up from there.
We had dinner with Bill and Jo in their U300 one night and then went to the fire to listen to the great karaoke so almost no juice used that evening. The Kw total charge the next day was almost nothing.
Pierce
Title: Re: Battery usage percentages
Post by: Paul Smith on February 22, 2014, 03:36:16 pm
Thanks, Pierce.
That explains it.
I'm in an RV Park in El Centro, CA for the winter and I'm thinking about unplugging my fridge from AC and running it on DC to reduce our electric bill (and have the solar pay for itself).
Any thots of a problem doing this?
best, paul
Title: Re: Battery usage percentages
Post by: John S on February 22, 2014, 05:01:21 pm
While you are plugged in the converter will produce 12 volts so it will still use electric current I would think.
Title: Re: Battery usage percentages
Post by: Pierce & Gaylie Stewart on February 22, 2014, 06:14:29 pm
Paul,
While all the modern fridges use 12V in one way or another, you just need to make sure your's is a 3 way refrigerator. Many are 2 way, 120V and propane and only use the 12V to power the logic board. You are probably thinking of unplugging it so it will force it to change over when it otherwise would default to 120V if available. Would save a few bucks that way.
Pierce
Title: Re: Battery usage percentages
Post by: Paul Smith on February 22, 2014, 08:19:35 pm
Mine is a 3 way. Cold plate technology. Made to order.
Title: Re: Battery usage percentages
Post by: P. Wyatt Sabourin on February 24, 2014, 11:33:48 am
How many amphours does it take to recharge a 700 amphour battery bank.
With a 700 amphour battery bank, each 10% of discharge provides 70 amphours. The charge efficiency is 90% at 50% charged but only 50% at 95% charged.
Recharging from 50% to 60% requires 80 amphours. Recharging from 60% to 70% requires 95 amphours. Recharging from 70% to 80% requires 110 amphours. Recharging from 80% to 90% requires 125 amphours. Recharging from 90% to 100% requires 140 amphours.
So recharging using your generator works well from 50% to 80%, however, above 80% charged, the charge rate must slow down and you are burning fuel for your generator but using only a small fraction of the available power. While the amphours required to recharge goes up as the battery charge percent increases, the amps going into your battery bank reduces, therefore the amount of time to recharge from 95% to 100% is much higher then the time required to charge from 50% to 55%.
Such is the nature of a battery.
Title: Re: Battery usage percentages
Post by: Caflashbob on March 01, 2014, 01:14:16 pm
So the real answer is that any battery is just an chemical/electrical device, which, like a tire, does not have an infinite life. If abused, the useable life of a battery can be as little as one year.
Thought of your actual tested results of the different types of 8D battery construction.
Matches the results posted by MK battery on their web site.
The 8G8D's at 10% discharge show a 6,000 cycle life. 20% was 2,000
AGM's at 10% discharge were 3,000 cycles. Similar results at the other discharge rates
Definite motivation for me to add more solar to our coach. The advantages of even more capacity may be worth dragging around additional batteries.
I did six sonnenschein(deka) 8d's in the 80's for a customer and he could run his roof airs for a few hours on the inverted batteries and they were rechargeable during the next days drive.
Not sure if they were gels then or AGM's?
They were expensive even then. $500? each.
Good 140 watt panels are available at $200 each range currently.
Someone here posted using a higher voltage commercial setup. What is your opinion on that?
I am starting to see the advantages of 1000 watts of solar to allow the three phase charging of the batteries as the last ten percent takes the longest time. Am I correct?
Need the best way financially and roof room to get closer to the 1,000 watt setup maybe.
Generator is nice but noisy on my 97. Need one in a box AND the solar setup maybe
Title: Re: Battery usage percentages
Post by: Tom Lang on March 01, 2014, 02:09:11 pm
My original gel 8D batteries gave me 10+ years of good service. I had to replace them a few months ago, and got a good deal on Lifeline AGM batteries. We'll see if I can repeat with another ten years of service.
I don't want to have the entire roof covered with raised solar panels, so decided to go with UniSolar panels. They are like strips of roll roofing that stick directly to the roof of the coach. I just received a pair of 136 Watt panels, each 15.5 inches wide by 18 feet long. I hope 272 Watts will give my just ordered 30 Amp Tracker MPPT charge controller enough power to provide around 20 Amps of charging in the middle of the day. If not, I will see if I can add another panel or two.
My plan is not to boondock entirely on solar power, but rather to run the generator for a couple of hours in the morning then top off the batteries during the day with solar.
Title: Re: Battery usage percentages
Post by: Pierce & Gaylie Stewart on March 01, 2014, 03:58:52 pm
So far in winter in Arizona, we peaked out at about 50% of the total potential in the middle of the day. Less up north where we live. Even at half your potential, it can replenish the batteries especially if you have converted to LEDs for lighting. Another plus is in case of generator failure, it can bring all batteries up for any kind of emergency starting, etc.
Summer sun will be a lot higher so will take less time to bring the batteries back up.
Pierce
Title: Re: Battery usage percentages
Post by: Pierce & Gaylie Stewart on March 01, 2014, 04:07:13 pm
Bob,
None of the larger panels are 12V. Ours are 36V with some available at 48V. Look around on Craigslist. Our 280 Watt panels were $170/ea new and work great. Same as the new operational solar field in the Mojave. The controller costs as much as the four panels. No need to pay anywhere near $1/watt as the prices have really come down. Still others trying to soak buyers though. Very pleased how our system works. Never start generator except for exercise perhaps every two weeks.
Pierce
Title: Re: Battery usage percentages
Post by: Tom Lang on March 01, 2014, 04:21:02 pm
So far in winter in Arizona, we peaked out at about 50% of the total potential in the middle of the day. Less up north where we live. Even at half your potential, it can replenish the batteries especially if you have converted to LEDs for lighting. Another plus is in case of generator failure, it can bring all batteries up for any kind of emergency starting, etc.
Summer sun will be a lot higher so will take less time to bring the batteries back up.
Pierce
This is part of the reason I chose the 30A mppt controller when two panels could supply 22A to the batteries, three panels 33A, and four panels 44A. Most of the time the current will be limited by the sun, once in a while by the controller.
This controller can handle 150 volts from the panels, which is safely above the open circuit voltage of three in series. These are 33volt nominal panels, and if I go to four panels, they will be connected series-parallel.
Title: Re: Battery usage percentages
Post by: fouroureye on March 01, 2014, 04:29:08 pm
Pierce,
Not trying to hijack but, that's a great price on those pannels ^.^d
Question, can you mix wattage? I have a C40 charge controler.
I have 12-75w. Could I replace 2, 3, 4 with the higher wattage? :help:
Title: Re: Battery usage percentages
Post by: Brad & Christine Slaughter on March 01, 2014, 05:29:44 pm
None of the larger panels are 12V. Ours are 36V with some available at 48V. Look around on Craigslist. Our 280 Watt panels were $170/ea new and work great. Same as the new operational solar field in the Mojave. The controller costs as much as the four panels. No need to pay anywhere near $1/watt as the prices have really come down. Still others trying to soak buyers though. Very pleased how our system works. Never start generator except for exercise perhaps every two weeks.
Pierce
Glad to hear prices have come down. Can you recommend a good primer for learning what to buy to set up solar? There is so much hype out there, it is hard to sort the facts from the fiction. Clearly, one small panel is better than NO panel at all, and two is better than one. But where should one start if they wanted to build a system progressively as needs expanded?
Title: Re: Battery usage percentages
Post by: Pierce & Gaylie Stewart on March 01, 2014, 06:04:46 pm
John,
I would take a photo of the label on the back of the panel with all the specs and then contact the C-40 controller retailer like Northern Arizona Sun and Wind or one of the other companies and see what they recommend. There are a lot of factors here and a lot of installation companies make major mistakes in installation. A large company did my neighbors and really botched the job.
Brad,
The 280 Watt panels have dropped another $10 each. Now $160 for each 280W panels. Here is the site: 280W SOLAR PANELS (http://sacramento.craigslist.org/mat/4335069185.html)
My best friend has been in solar panel development for his business for many years. I asked him for information as he is always at one of the big Chinese factories and he said Yingli panels are top quality and the price is the lowest a very large solar company here in the states could get if they made a large volume purchase. The seller is part of a crew that installed 80,000 in the Mojave. 500,000 of these panels have been installed in the U.S. No tax on these panels, what you see is what you pay.
So, total was $170 x 4 (or now $160 x 4) plus about $610 plus $12 shipping, no tax for the MidNite Classic 150 plus wires, aluminum for roof standoff mounts, fittings. Using the best quality materials available, about $1600 total for 1140 watts up top. The efficiency goes way up if they can be tilted toward the sun but I didn't want to have to climb up and possibly fall off sooner or later.
Our 102" U300 was perfect for the installation of four with only the batwing having to be turned 90 degrees and the rear radio antenna removed. Other coaches, even though longer or different floor plan may not be as easy. It took a LONG time to figure out all the details. Glad to help with the issues I had and always have time to answer any questions over the phone or with a PM. I just went to a lot of forums, sites, did a ton of reading and tried to weed out the fact from the fiction.
Glad to try and arrange for panel purchase from this guy. Have been to his house several times and watched as trailers would stop and pick up 10 or 20 panels. He has a LOT more than 10 for sale!
I purchased my batteries the same way just watching Craigslist.
Pierce
Title: Re: Battery usage percentages
Post by: Brad & Christine Slaughter on March 01, 2014, 08:23:29 pm
... So, total was $170 x 4 (or now $160 x 4) plus about $610 plus $12 shipping, no tax for the MidNite Classic 150 plus wires, aluminum for roof standoff mounts, fittings. Using the best quality materials available, about $1600 total for 1140 watts up top.
I just want to dip my feet into solar at this point. I'm not sure how much that means, and I am confused as to why they use watts as the measurement instead of amperage. I could understand if I was told that a particular solar array that would put (up to) 25 amps into my battery bank in a 5 hour day, but with the different panel voltages being cited...like 36 volts...48 volts... I am a bit lost. If you have "1140 watts on top", what does that mean in terms of amperage fed back into a 12 volt battery in a day? I have not been back out since installing my Trimetric, so I am not really sure how much I use in a normal day yet...i.e., what I would need to replace. At this point, I would just like to reduce generator time a bit, but I'm not seeking to completely eliminate it yet.
Title: Re: Battery usage percentages
Post by: Tom Lang on March 01, 2014, 08:40:46 pm
Watts are no more than the result of multiplying Amps times Volts. Just divide the Watts on the roof by 12 or 13 (volts in the battery) to see how many Amps it can theroetically pump into the battery under the best of conditions. If you get a MPPT solar charge controller, it makes no difference the voltage of the panels so long as it is below the maximum the controller can handle. If you get a lower-cost PWM controller, some of that power will be lost.
I bought a MPPT comptroller that can handle a maximum of 150 volts from the panels. This way, I can wire three of the 33volt nominal, 42volt open circuit, panels in series and not exceed the capability of the controller. Everything the panels can deliver will be converted to 12-13 volts and pumped into the batteries, up to the maximum of the controller, which is 30 Amps.
If I am every fortunately enough that the panels are trying to supply a full 136 watts each, that would give me 31.8A to the batteries at 13 volts. At this point, the controller would have hit it's limit of 30A, and the batteries would not get that last 1.8A the panels want to supply. Too bad.
I may go with four panels, in which case they would be hooked up in series-parallel in order to not exceed the maximum panel voltage. In this case, bright sunny days would frequently see me limited to 30A, but for more hours than I would see 30A with fewer panels.
Title: Re: Battery usage percentages
Post by: J. D. Stevens on March 01, 2014, 08:48:27 pm
Watts = Amps X Volts
Watts is a measure of power. A panel that produces 12 amps at 12 volts produces 144 watts of power. A panel that produces 12 amps at 24 volts produces 288 watts of power. Using only amps to compare panels doesn't provide enough information to rate the power the panel can deliver under ideal conditions.
My understanding is that the MPPT controllers can take power at a voltage higher than 12.6 VDC (nominal, it takes about 13-14.5 volts to actually charge the battery) and convert it to the best combination of voltage and current for charging your battery.
I offer this as a start to add to your education (confusion?). Others may be able to explain more clearly.
Title: Re: Battery usage percentages
Post by: Brad & Christine Slaughter on March 01, 2014, 10:15:18 pm
I have a pretty good understanding of Ohm's Law (WA7QOK), but the missing piece to me was that whatever the voltage of the panels, I am now understanding that the controller is used to transform it into the 12-14volt range to fit the need. That makes it quite a bit clearer. Thanks!
Title: Re: Battery usage percentages
Post by: J. D. Stevens on March 01, 2014, 11:36:41 pm
I have a pretty good understanding of Ohm's Law (WA7QOK),
K5ERP here. Originally KN5ERP in 1955. Held novice, technician, general, advanced, and now hold extra. I haven't been active, but I do keep the license up. That doesn't mean I know or understand anything, but I was able to pass the test and copy code up to 20 wpm.
I'm pleased a couple of us were able to clarify the issue regarding panel voltage.
I like the idea of solar and was able to see it in use during my brief adventure to Quartzsite. We seldom boondock and are "part timers," so solar power for us is like the whole "motor coach" adventure: interesting and fun, but not economically sound. :P
Title: Re: Battery usage percentages
Post by: Brad & Christine Slaughter on March 02, 2014, 12:40:49 am
so solar power for us is like the whole "motor coach" adventure: interesting and fun, but not economically sound. :P
I was KN7YAX to start with. 1963, I think, at age 14. I stopped at Advanced and am waiting to either die or get grandfathered to Extra. Christine is N7QOK.
Boy, that is exactly correct. Not economically sound...but a lot of fun and adventure. That is sort of where I am at. I'd just like to play a bit with it, but not to the level of 1140 watts.
Title: Re: Battery usage percentages
Post by: Pierce & Gaylie Stewart on March 02, 2014, 12:42:09 am
Brad,
You are just starting to grasp the complexity of all the possibilities in setting up a complete solar system from the PV panels to the batteries. Just understanding a MPPT controller takes a while to only partially figure out. Once you have studied it, installed it and it works as expected, it's a real feeling of accomplishment. A larger system is not really much more complicated than a small one.
For us, running the generator took away part of the reason for being outside in nature. I just never completely relaxed with it running. With so many campgrounds here mixing tents with RVs, I always expected a dirty look when I looked outside. Part of it was that some motorhomes ran their generators well past the campground hours and started them an hour or two before they were supposed to. The other part is being sort of a pioneer in harnessing the sun's power to live without constantly depleting our resources. Everyday, more and more homes and vehicles are now using this technology. It still seems a little magical touching a button and getting mostly pollution free electricity. Might be one of the good things that came with high oil prices.
Pierce
Title: Re: Battery usage percentages
Post by: Tom Lang on March 02, 2014, 02:48:24 am
MPPT Tracer3215RN 30A 150V Solar Battery Charge Controller Regulator US Stock $167
2 x 136 watt Flexible Solar Panel Peel & Stick by Uni-solar. PVL136 Unisolar $310
These two eBay purchases make up the core of my first foray into solar. If needed, I can add another panel or two.
I don't expect to boondock totally generator free in the winter when the propane furnaces and more hours of lighting take a toll on the batteries, but I want to use the generator less and let the solar panels top off the batteries each day. In the summer, with no use of the furnaces and more daylight, the generator should see little use except for air conditioning.
Title: Re: Battery usage percentages
Post by: lgshoup on March 02, 2014, 07:57:01 am
Try to keep in mind that the amperages, etc, in the advertising is just that...advertising. In the real world you'll never get the full output even if you tilt and track the sun. Light dust, degradation of the surface, loss over connectors, etc, will drop you down at least 10% on your best days. We have 465 watts of solar and are very happy getting 26 amps at the controller. in theory it should be 465/13.8 or 33.696. That's never going to happen. We have a 30 amp controller and all's right with the world.
Title: Re: Battery usage percentages
Post by: fouroureye on March 02, 2014, 08:10:51 am
Hey Larry,
Can I ask you something about my set up?
900w in 12-75w panels, 40A controler
Looking at removing 2-4 panelsand updating with these 270w panels. Can you mix wattages? :-\
Title: Re: Battery usage percentages
Post by: Paul Smith on March 02, 2014, 09:33:13 am
JD,
In for a penny, in for a pound ... ;o)
best, paul
Quote
like the idea of solar and was able to see it in use during my brief adventure to Quartzsite. We seldom boondock and are "part timers," so solar power for us is like the whole "motor coach" adventure: interesting and fun, but not economically sound.
Title: Re: Battery usage percentages
Post by: Paul Smith on March 02, 2014, 09:41:55 am
Tom,
I'm not sure the amount of solar you're considering will top off the batteries.
Others here are more knowledgeable and can chime in.
best, paul
Quote
I don't expect to boondock totally generator free in the winter when the propane furnaces and more hours of lighting take a toll on the batteries, but I want to use the generator less and let the solar panels top off the batteries each day. In the summer, with no use of the furnaces and more daylight, the generator should see little use except for air conditioning.
Title: Re: Battery usage percentages
Post by: Pierce & Gaylie Stewart on March 02, 2014, 09:52:46 am
Like other lurkers, been giving some thought to the solar idea, but since my setup is Gel, I have to ask how tuneable are the controllers as to max voltage limit (14.2VDC Gel).
Very tuneable for all voltages including even the display voltage. Check the owner's manual for ours at: http://www.midnitesolar.com/pdfs/classicManual.pdf (http://www.midnitesolar.com/pdfs/classicManual.pdf) Lot of good YouTube videos too.
Pierce
Title: Re: Battery usage percentages
Post by: John Haygarth on March 02, 2014, 11:10:57 am
Brad, we will most probably be going thru L havusa on way down to Lukeville this next weekend so can stop for a coffee if you want to look at our set up. Not as big as Peirce's but we live off it mostly as we do not use AC (open windows and use fan) but do have residential fridge on all the time. We do not have a cell so would have to call you once there or meet at your place. Up to you. JohnH
Title: Re: Battery usage percentages
Post by: Brad & Christine Slaughter on March 02, 2014, 12:01:27 pm
Try to keep in mind that the amperages, etc, in the advertising is just that...advertising. In the real world you'll never get the full output even if you tilt and track the sun. Light dust, degradation of the surface, loss over connectors, etc, will drop you down at least 10% on your best days. We have 465 watts of solar and are very happy getting 26 amps at the controller. in theory it should be 465/13.8 or 33.696. That's never going to happen. We have a 30 amp controller and all's right with the world.
So, to try to understand this, if you see 26 amps at your controller, and if you get that for 4 hours a day of bright sun, are you then sending (up to) 104 amps total to the battery in that 4 hour period? Do I have it right?
John, sent you a PM. Thank you!
Title: Re: Battery usage percentages
Post by: Tom Lang on March 02, 2014, 12:23:46 pm
Try to keep in mind that the amperages, etc, in the advertising is just that...advertising. In the real world you'll never get the full output even if you tilt and track the sun. Light dust, degradation of the surface, loss over connectors, etc, will drop you down at least 10% on your best days. We have 465 watts of solar and are very happy getting 26 amps at the controller. in theory it should be 465/13.8 or 33.696. That's never going to happen. We have a 30 amp controller and all's right with the world.
Well aware of that. This is one reason why a tri-metric battery monitor is going in at the same time as the solar, and also why I got the controller that can use a third panel wired in series or two more panels paralleled with the first two. Once I have some real world experience, I can see if another panel or two is called for.
Title: Re: Battery usage percentages
Post by: Tom Lang on March 02, 2014, 12:33:05 pm
I'm not sure the amount of solar you're considering will top off the batteries.
Others here are more knowledgeable and can chime in.
best, paul
Me neither. Again, this is why the tri-metric is an essential part of this experiment. I can always run the generator a little more or try and use less power and see how it goes, and I have kept my options open for adding more panels. We'll see how it goes.
And keep in mind that this is in the winter when I use the mist electricity and see the least sun. I believe summer use will be just fine.
And another reason for having solar is for storing the coach and accidentally losing shore power, I won't come back to dead batteries (again).
Title: Re: Battery usage percentages
Post by: Tom Lang on March 02, 2014, 12:39:16 pm
So, to try to understand this, if you see 26 amps at your controller, and if you get that for 4 hours a day of bright sun, are you then sending (up to) 104 amps total to the battery in that 4 hour period? Do I have it right?
John, sent you a PM. Thank you!
Yes, 104 Amp-hours in.
Keep in mind that you will get more than that, as the solar power is adding Amps all day long, just not as strongly when the sun is lower in the sky. I read somewhere that the total of those 4 hours plus the rest of the day is equivalent to 6 hours of bright sun in the winter, much more in the summer.
Title: Re: Battery usage percentages
Post by: P. Wyatt Sabourin on March 02, 2014, 12:40:00 pm
Caflashbob
I bought five 250 watt panels for $240 each from Solar Mike Gohl at the Slabs. He has more. Panels are available online for less than $1.00 per watt.I replaced fourteen 55 watt panels to reduce the size of the footprint and can walk around them easier now. Mike took my 55 watt panels in trade so I did not have to sell them - easier for me.
Many solar controllers today are able to convert up to 150 volts DC from panels to battery recharge voltage (13.4 to 14.6 volts). The advantage of higher voltage is it allows using smaller wires. The disadvantage of higher voltage is that the efficiency of the controller is reduced by higher voltage (higher input voltage means less watts into the batteries). It also means there is an increased shock risk. One of my friends here has wired four 29 volt (MPPT volts) in series to bring almost 120 MPPT volts off the roof (152 VOC). I wired five panels in parallel bring 29 volts off the roof but had to use much heavier wires then he did.
This statement is correct: I am starting to see the advantages of 1000 watts of solar to allow the three phase charging of the batteries as the last ten percent takes the longest time.
I recharge batteries with the generator once or twice a year.
Here is some practical numbers for designing a solar system. A 100 watt panel will provide up to 6.3 amps into a battery. If panels are installed flat on the roof, a 100 watt panel will provide about 3 amps into a battery for 6 hours, so about 18 amphours per day. With 1200 watts, I have up to 220 amphours available each day. I often run a roof fan on low (5amps) for 10 hours (50 amphours) which leaves 170 amphours per day for battery charging. In the morning my amphour meters show 40 to 140 amphours used overnight (all LED lights and LCD TVs). The only days that my batteries are not fully charged by 3pm is when it is raining.
You could by being power frugal get along quite well on 600 watts which will provide 110 amphours per day. I just do not wish to be that frugal.
Title: Re: Battery usage percentages
Post by: Caflashbob on March 02, 2014, 01:05:16 pm
I contacted the seller listed here for the 240 watt 36volt yingli panels. No reply yet. Flat on roof the capacity should work better with four?
Would have enough capacity to run a household refer with maybe a fourth 8g8d. Not intending to as not needed yet.
Title: Re: Battery usage percentages
Post by: Pierce & Gaylie Stewart on March 02, 2014, 01:23:24 pm
So, to try to understand this, if you see 26 amps at your controller, and if you get that for 4 hours a day of bright sun, are you then sending (up to) 104 amps total to the battery in that 4 hour period? Do I have it right?
John, sent you a PM. Thank you!
Brad,
Easier to think in watts not amps as panels are rated in watts but batteries are in amps so good to be able to convert back and forth. The watt rating is AT THAT MOMENT and not related to time. An example is solar panels putting out 1000 watts. One hour is 1 kilowatt hours or 1 kWh. Most controllers total the amount of watts for that day after two hours of inactivity. They will also keep track of past day's performance also with numbers as well as graphs. See page 48 of the MidNite owner's manual at: http://www.midnitesolar.com/pdfs/classicManual.pdf (http://www.midnitesolar.com/pdfs/classicManual.pdf)
On a day after we had used the most juice the night before in Quartzsite, the LCD display the following night showed we had put 2.5 kWh into the batteries. It can also show a graph for time of day/watts.
The controller has a capability of hundreds of settings, history, etc. and takes a long time to read, re-read and re-read again before you start to have a grasp of all the functions. On the other hand, the default settings are ready to plug and play in just several minutes. Good YouTube tutorial videos.
Will also output to Mac or PC with the info. Tablets coming soon.
Here is an idea of sizing from AM Solar that also give a good example of the watts to amps relationship.
quote:
"Let's say you were able to "boondock" for two days before you noticed your batteries getting weak.
First we have to determine what your batteries storage capacity is. Let's say you have two (2) relatively new Group 27 deep cycle batteries that are rated at 100 amp-hours of storage each. This means you theoretically have 200 amp-hours of energy to draw on (2 x 100 = 200). However, only about 80% of that is usable so you really only have 160 amp-hours of energy to draw on (0.8 x 200 = 160).
Once we have established what your batteries storage capacity is we divide it by the number of days you "boondocked" (in this example it was 2 days). So, 160 amp-hours of storage divided by 2 days = 80 amp-hours of energy consumed on the average day.
Now we need to determine how many solar panels you will need to replace that 80 amp-hours of energy you consume per day. We will assume that you use you RV during the sunnier half of the year and/or you follow the sun south during the darker half of the year. This will give you an average of five (5) "peak sun hours" per day.
A 100 watt panel produces an average of about 6 amps per peak sun hour, or about 30 amp-hours per day.
Given the above example, you would need three 100 watt solar panels to fully recharge on the average day."
end quote
Pierce
Title: Re: Battery usage percentages
Post by: Brad & Christine Slaughter on March 02, 2014, 03:34:49 pm
I think I get the electric calculations of it all.
Next step is to ask why I'd want to spend $610 on a controller, when it seems that I could get one for less than $200 with enough capacity to handle what I decide to put up there. I do not really care about the infinite amount of metrics that some controllers would display for me, as I think all I really want to know is told to me by the Trimetric I have (and the Prosine readouts). At this point in my life, I don't want a lot of extra data to think about; I have too many other challenges. BUT, on the other side, I do not want to spend too little if something isn't really going to work and last and that is why it is cheaper.
To dumb it down in the simplest terms I am thinking about: Starting out with a full battery bank (2 x 225A), if I have a lot of electricity use going on and it's cloudy outside with the Trimetric showing a falling battery voltage, I know what's gonna happen. It will be generator time sooner rather than later. But if it's sunny outside and the Trimetric shows 13 volts and no negative flow out of the batteries, then I know I can turn another appliance on if I need or want to do so while it is still sunny outside.
Starting out with NO solar, anything will be an improvement on reducing generator time. I realize it is NOT really cost-efficient, but it would be nice to get a bit of quiet power added to the batteries, especially being headquartered in Arizona where finding sun isn't a problem. Maybe after the apocalypse, I'll wish I had 2kw up there.
Title: Re: Battery usage percentages
Post by: Pierce & Gaylie Stewart on March 02, 2014, 03:40:25 pm
You could start with a much less expensive Chinese controller that would handle one or two smaller panels and then add another later. Nothing wrong with two controllers on one set of batteries.
Pierce
Title: Re: Battery usage percentages
Post by: Brad & Christine Slaughter on March 02, 2014, 04:33:05 pm
Screwing something into the roof is my next fear to worry about.
Title: Re: Battery usage percentages
Post by: Pierce & Gaylie Stewart on March 02, 2014, 04:42:38 pm
There are 100 plus holes now. A lot of owners use a special adhesive and don't drill. I didn't want any possible issues with the big panels so drilled.
Pierce
Title: Re: Battery usage percentages
Post by: Tom Lang on March 02, 2014, 05:53:08 pm
I think I get the electric calculations of it all.
Next step is to ask why I'd want to spend $610 on a controller, when it seems that I could get one for less than $200 with enough capacity to handle what I decide to put up there. I do not really care about the infinite amount of metrics that some controllers would display for me, as I think all I really want to know is told to me by the Trimetric I have (and the Prosine readouts). At this point in my life, I don't want a lot of extra data to think about; I have too many other challenges. BUT, on the other side, I do not want to spend too little if something isn't really going to work and last and that is why it is cheaper.
To dumb it down in the simplest terms I am thinking about: Starting out with a full battery bank (2 x 225A), if I have a lot of electricity use going on and it's cloudy outside with the Trimetric showing a falling battery voltage, I know what's gonna happen. It will be generator time sooner rather than later. But if it's sunny outside and the Trimetric shows 13 volts and no negative flow out of the batteries, then I know I can turn another appliance on if I need or want to do so while it is still sunny outside.
Starting out with NO solar, anything will be an improvement on reducing generator time. I realize it is NOT really cost-efficient, but it would be nice to get a bit of quiet power added to the batteries, especially being headquartered in Arizona where finding sun isn't a problem. Maybe after the apocalypse, I'll wish I had 2kw up there.
That is prettymuch my thinking. Starting out with two 136 Watt panels, upgradable to four with the same controller.
Title: Re: Battery usage percentages
Post by: Bill Willett on March 02, 2014, 06:01:22 pm
I thought Uni Solar went bankrupt.
Title: Re: Battery usage percentages
Post by: Tom Lang on March 02, 2014, 06:02:14 pm
You could start with a much less expensive Chinese controller that would handle one or two smaller panels and then add another later. Nothing wrong with two controllers on one set of batteries.
Pierce
Have you checked this out with the controller manufacturer or in real life? It might be true with old tech linear analog charhe controllers, but today's pwm and mccp controllers migght have voltage spikes getting in each othervs way. I see the possibility of the feedback systems going completely haywire.
Title: Re: Battery usage percentages
Post by: Tom Lang on March 02, 2014, 06:04:07 pm
Have you checked this out with the controller manufacturer or in real life? It might be true with old tech linear analog charhe controllers, but today's pwm and mccp controllers migght have voltage spikes getting in each othervs way. I see the possibility of the feedback systems going completely haywire.
Don't know about other brands but MidNite has a "follow me" firmware that allows any number of their controllers to be daisy chained.
Pierce
Title: Re: Battery usage percentages
Post by: Roland Begin on March 02, 2014, 10:00:38 pm
I think I get the electric calculations of it all.
Next step is to ask why I'd want to spend $610 on a controller, when it seems that I could get one for less than $200 with enough capacity to handle what I decide to put up there. I do not really care about the infinite amount of metrics that some controllers would display for me, as I think all I really want to know is told to me by the Trimetric I have (and the Prosine readouts).
Controllers are not all equal. You get the most of the available solar energy conversion from an MPPT controller. They are more efficient, versatile and "kinder" to your batteries. Research early on saves many $$$$ later. Don;t ask me how I know.
Roland
Title: Re: Battery usage percentages
Post by: Brad & Christine Slaughter on March 02, 2014, 10:31:49 pm
Quote
author=Roland Begin link=topic=20460.msg150768#msg150768 date=1393815638
Controllers are not all equal. You get the most of the available solar energy conversion from an MPPT controller. They are more efficient, versatile and "kinder" to your batteries. Research early on saves many $$$$ later. Don;t ask me how I know.
Roland
I understand. The smartest among us are usually the ones who have already made the most mistakes. I do understand the value of the MPPT controllers, but even they seem to vary wildly in price for the same amperage capability. I'll keep accumulating info!
Title: Re: Battery usage percentages
Post by: RRadio on March 02, 2014, 10:42:40 pm
Would expensive batteries, photovoltaic arrays, and their associated equipment really last long enough to pay for themselves before they go bad? Even with diesel at $4 per gallon I can run my genset for several years of battery charging for that kind of money... just saying... always the voice of the cheapskate on here ;D
Title: Re: Battery usage percentages
Post by: Brad & Christine Slaughter on March 02, 2014, 10:52:45 pm
Would expensive batteries, photovoltaic arrays, and their associated equipment really last long enough to pay for themselves before they go bad? Even with diesel at $4 per gallon I can run my genset for several years of battery charging for that kind of money... just saying... always the voice of the cheapskate on here ;D
Nope. They wouldn't. And motels are cheaper than using a motorhome, but....
Title: Re: Battery usage percentages
Post by: Caflashbob on March 02, 2014, 11:10:49 pm
Would expensive batteries, photovoltaic arrays, and their associated equipment really last long enough to pay for themselves before they go bad? Even with diesel at $4 per gallon I can run my genset for several years of battery charging for that kind of money... just saying... always the voice of the cheapskate on here ;D
Does not compute easily. 50% of the value to me is the quiet power. For me and everyone around me......
Bob
Title: Re: Battery usage percentages
Post by: Tom Lang on March 03, 2014, 12:37:29 am
I understand. The smartest among us are usually the ones who have already made the most mistakes. I do understand the value of the MPPT controllers, but even they seem to vary wildly in price for the same amperage capability. I'll keep accumulating info!
Read the reviews before buying one. There are Chinese controllers on the market claiming to be mppt at unbelievable low prices. Do the research and you will find them to be Pwm, not mppt.
Title: Re: Battery usage percentages
Post by: John S on March 03, 2014, 08:15:38 am
Would expensive batteries, photovoltaic arrays, and their associated equipment really last long enough to pay for themselves before they go bad? Even with diesel at $4 per gallon I can run my genset for several years of battery charging for that kind of money... just saying... always the voice of the cheapskate on here ;D
I had solar on my first unit. I just added an extra battery and can go all night. I will want the genset in the morning anyway so I just turn it on. Simple and cheaper yes and what happen when you get a few days of rain. It is fine if you are in the desert buy in the mountains with heavy tree cover it will not work either. Shade is more important to me then not running the genset.
Title: Re: Battery usage percentages
Post by: Roland Begin on March 03, 2014, 11:19:54 am
Would expensive batteries, photovoltaic arrays, and their associated equipment really last long enough to pay for themselves before they go bad? Even with diesel at $4 per gallon I can run my genset for several years of battery charging for that kind of money... just saying... always the voice of the cheapskate on here ;D
Cost of running a generator is more than the coast of fuel, you have to account for maintenance and repair issues and there are also environmental issues to be considered.
Roland
Title: Re: Battery usage percentages
Post by: John S on March 03, 2014, 07:05:45 pm
True but I can maintain it for a Long time with the costs of solar. I put it on my first coach but decided against it on the next two. Did not see the benefit as the trees shaded everything here in the mountains and unless I was out west or at the beach they did not produce. Add to the fact that all summer I want ac and that just makes me agree with Scott.
Title: Re: Battery usage percentages
Post by: Tom Lang on March 03, 2014, 07:24:19 pm
Which is why I am only going with 272 watts with some room for expansion. Enough watts to help top off the batteries after running the generator for the purpose of battery health. With the added benefit of keeping the batteries charged during storage, either short periods with the refrigerator running on propane or longer periods with the refrigerator off.
Title: Re: Battery usage percentages
Post by: John S on March 03, 2014, 07:36:04 pm
Storage is a good reason to use solar. In fact one of the best but now I have a garage and will try to always have one.
Title: Re: Battery usage percentages
Post by: Tom Lang on March 04, 2014, 02:34:42 am
Exactly.
I could see driving to a cruise ship port, and taking a cruise with the coach in dry storage with the refrigerator running.
Now for the 64 dollar question. I know I can go quite long doing this on propane. But how about plugging the 2-way refrigerator into the inverter ac receptacle and running from battery power. Is this feasible, making an RV refrigerator act like a residential model? How much power would it take each day?
Title: Re: Battery usage percentages
Post by: red tractor on March 04, 2014, 09:23:05 am
running the refrigerator on ac from the inverter is not a good way to go as it will kill your batteries very quickly
Title: Re: Battery usage percentages
Post by: Paul Smith on March 04, 2014, 09:36:41 am
The Dometic I used to have used DC when it ran on electric instead of propane. The DC is used to heat the system. DC will kill your batteries quick, too.
best, paul
Title: Re: Battery usage percentages
Post by: lgshoup on March 04, 2014, 01:04:09 pm
Looking at removing 2-4 panelsand updating with these 270w panels. Can you mix wattages? :-\
You can mix wattages. just keep the total within reason with your controller.
Title: Re: Battery usage percentages
Post by: fouroureye on March 04, 2014, 01:31:29 pm
Thanks Larry, sounds like I might be getting a couple of 270w panels ^.^d
that will increase my capacity; 2 @ 270 watts @ 60% capacity because of dirt clouds no tilt etc =720watts input 3 @ 270w =940watts input 4 @ 270w = 1000watts input
Title: Re: Battery usage percentages
Post by: Pierce & Gaylie Stewart on March 04, 2014, 01:45:38 pm
Make really sure your voltage does not exceed the controller rated voltage. Remember, in the morning, a cold PV panel will put out more voltage than the rating on the lable. I could have gone all series wiring and on paper, would have seen 144 volts with the Classic 150 being rated for 150 volts but was advised the voltage on an all series wiring on a cold morning could exceed 150 volts by a significant amount. Controllers will either not turn on until the voltage drops or will be fried and not covered by the warranty. As the sun is starting to come over the horizon in the morning, our controller indicates over 80 volts (four 36 volt, 280w panels in series/parallel) but won't turn on until enough watts become available. Our panels have a 92 amp potential with the MidNite 150 maxing out at 96 amps so this is also an important consideration in planning the installation. In other words, we have maxed out the wattage/amperage the controller can handle. If any doubts or questions, call the controller retailer or manufacturer and ask questions.
With the panels flat on the roof and dirty, we still get 80+ volts in the very early morning from a 2 x 36 volt panels series wiring that would normally see 72 volts. They are also shaded by the AC at that time.
Pierce
Title: Re: Battery usage percentages
Post by: fouroureye on March 04, 2014, 02:18:14 pm
Thanks Pierce good advice. ^.^d
Title: Re: Battery usage percentages
Post by: Tom Lang on March 04, 2014, 07:54:28 pm
Just note that you can only safely parallel connect banks of solar panels if each bank produces exactly the same voltage, otherwise you will be applying the voltage differential across a length of wire, heating the wire, possibly to destruction, and wasting power.
I would feel safest if each parallel connected bank is the same configuration and the same solar cell type, otherwise there might be small differences in voltages under identical conditions. I wouldn't try paralleling an amorphous UniSolar cell with a traditional crystalline cell, or two cells from different manufacturers with different blocking diodes used or not used.
Series connections on the other hand are just fine, as long as you never under any conditions (for example no load and cold) exceed the controllers max PV voltage.
Title: Re: Battery usage percentages
Post by: Tom Lang on March 05, 2014, 02:51:40 am
running the refrigerator on ac from the inverter is not a good way to go as it will kill your batteries very quickly
Maybe. My RV refrigerator uses two 210 watt ac heater elements. How does this 420 Watts compare with the power used by a residential refrigerator? I assume the duty cycle to maintain a static temperature would be pretty similar.
Title: Re: Battery usage percentages
Post by: Dave M (RIP) on March 05, 2014, 10:32:12 am
Think I have read most of the installments here on the Battery useage and the PV Cell use, wire size, wire run, length, amp draw, voltage drop etc. My question concerns those that are using the electric heat in bath and front flooring. I have no idea of the kw draw on the battery, I do not know if the heat strips are 12 VDC or 120 VAC, surely someone has considered this issue, this will surely come up one day, so am wondering. Dave M
Title: Re: Battery usage percentages
Post by: fouroureye on March 05, 2014, 01:22:14 pm
Easy heat - warm tiles, which we use mostly in bathrooms as follows; Mat type 2' width vs length
60 sq ft - 720watts, 6A 75 sq ft - 900watts, 7.5A 90 sq ft - 1020watts, 8.5A
Use the flex grout in a can - will color code to any MAIP grout color