Battery usage percentages

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Battery usage percentages

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

Re: Battery usage percentages

Reply #1 – 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.

Re: Battery usage percentages

Reply #2 – 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.

Re: Battery usage percentages

Reply #3 – February 14, 2014, 08:36:06 am

I follow the same practices as Bruce.

Re: Battery usage percentages

Reply #4 – February 14, 2014, 08:39:09 am

Quote from: amos.harrison – February 14, 2014, 08:36:06 am

I follow the same practices as Bruce.

X2

The other Brett

And, while 50/85 is OK, at least once a week, the batteries need to be brought to 100% to retain full capacity.

Re: Battery usage percentages

Reply #5 – 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

Re: Battery usage percentages

Reply #6 – 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.

Re: Battery usage percentages

Reply #7 – February 14, 2014, 01:17:38 pm

Quote from: wolfe10 – February 14, 2014, 12:18:24 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.

Re: Battery usage percentages

Reply #8 – 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.

Re: Battery usage percentages

Reply #9 – February 15, 2014, 04:37:52 pm

Quote from: John S – 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.

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.

)

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.

Re: Battery usage percentages

Reply #10 – 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

Re: Battery usage percentages

Reply #11 – February 15, 2014, 04:53:31 pm

Wonder if your charger is cooking your batteries

Re: Battery usage percentages

Reply #12 – 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.

Re: Battery usage percentages

Reply #13 – February 15, 2014, 06:22:21 pm

Quote from: J. D. Stevens – February 15, 2014, 04:37:52 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

Re: Battery usage percentages

Reply #14 – 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.

Re: Battery usage percentages

Reply #15 – 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.

Re: Battery usage percentages

Reply #16 – February 15, 2014, 06:44:50 pm

Quote from: wolfe10 – February 15, 2014, 06:29:28 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

Re: Battery usage percentages

Reply #17 – 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.

Re: Battery usage percentages

Reply #18 – 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

Re: Battery usage percentages

Reply #19 – 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.

Re: Battery usage percentages

Reply #20 – 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.

Re: Battery usage percentages

Reply #21 – February 21, 2014, 11:42:56 am

Quote from: RRadio – 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.

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.....

Re: Battery usage percentages

Reply #22 – 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

Re: Battery usage percentages

Reply #23 – 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.

Re: Battery usage percentages

Reply #24 – 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.

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