...............................................Lifeline Tech support was a great help when it came to re-configureing the Prosine charger for the new AGM's.
Cost me some bucks but I won't have to think about batteries for a while.....................................
Dean, OK. Before the change-out, you had MK Gel Cells House and Optima Yellow Top AGM Engine batteries. Don't forget that your alternator voltage regulator also needs attention. If it was properly set before, it should have been supplying 13.8 to 14.1 Vdc, at the positive battery post of the MK's (and on your camera display), downstream of the battery isolator. I say at the MK's because they were the more "fragile" and "sensitive" of the House gel vs. Engine AGM battery banks and if the PO did it properly, the regulator should have been adjusted to not overcharge the MK's. Also if properly set for the MK's, the alternator was seriously undercharging your Optima AGM's (they needed 14.7 Vdc nominal ideal charge voltage), which would also make the AGM Optima's appear to be very weak when you load tested them.
With your much better, new AGM house and engine battery setup, an ideal situation would call for an alternator adjusted to 14.7 VDC Nominal voltage at the positive battery terminals of both banks (with the engine at 1K RPM or higher). If you don't have an adjustable voltage regulator, I'd take the whole alternator off and to a good reputable Starter/Alternator/Generator shop and have them set you up with one (or a fixed output 0.5 to 0.9 Vdc higher than the 14.7 Vdc to account for the battery isolator diode voltage drops).
Of course putting accurate dash readouts on both banks and adding battery isolate solenoids (similar to a Blue Sea [PN-9012] Marine, latching, battery boost solenoid) would be even more ideal, now that you've recently experienced the joy and expense of new battery banks. From experience, though, one doesn't have to get that fancy. I just mentally compensate for the known offsets in my dash (engine) and Javelina (house batteries) displays and use common sense in battery drawdowns and shorepower/generator vs. alternator charge cycles. Knock on wood, my 2002 red top Optimas and MK's (ALL GEL CELLs) are still strong and doing very well. Best wishes and Life IS Good! Neal
Title: Re: New battery setup (was RE: House Batteries boiling)
Post by: Dean & Dee on December 04, 2012, 06:54:51 am
Dean, OK. Before the change-out, you had MK Gel Cells House and Optima Yellow Top AGM Engine batteries. Don't forget that your alternator voltage regulator also needs attention.
Thanks Neal. That's very good information. I was wondering if anything should be changed pertaining to the alternator but was not sure what or how to do it.
I guess I have to do some research now to figure out how to go about it. I do not know if my voltage reg. is adjustable or not or how to go about it just yet. If anyone can give me some input as to what to look for or a photo or two that would be great.
I will do some seaching on here and Barry Beam's site to see what I can find.
I am also waiting to here back from Lifeline to see what the battery temp coefficient should be set at. The tech had to talk to his engineer to get some feedback.
Again, Thanks for the heads up!
Dean
Title: Re: New battery setup (was RE: House Batteries boiling)
Post by: Dean & Dee on December 04, 2012, 08:18:19 am
Okay, I found some info on Barry Beams site pertaining to Voltage Reg. adjustment. Voltage Regulator Adjustment (http://beamalarm.com/Documents/voltage_regulator_adjustment.html) I also crawled under the coach to get a peek at the alternator and verified it is adjustable.
Before I make any changes I will fire up the coach and recheck the charging voltage. With the old batteries it was reading 13.9V at 1200 RPM. So it should be closer to 14.7V ? When I set up the house charger for the new AGM house batteries I believe it's set for 14.3V's.
Just want to make sure I get the settings best suited to keep those pricy new batteries in good shape.
Dean
Title: Re: New battery setup (was RE: House Batteries boiling)
Post by: Dean & Dee on December 04, 2012, 09:53:32 am
So I am still waiting to hear back from Lifeline on what the house charger "battery temp coefficient" shoud be set at for the new AGM's. Right now it's set at -11.66mV/ F but that was for the Gels.
Can anyone with AGM's give me some insight what theirs is set at?
Thanks, Dean
Title: Re: New battery setup (was RE: House Batteries boiling)
Post by: Dean & Dee on December 04, 2012, 10:39:38 am
More info. I have checked the charging voltage from the alternator to the Isolator at 1500 RPM...it is 14.73V Then at the start batt's I read 13.85V at the house batts...13.87V.
Should I crank up the voltage to read 14.5ish v at the batterys?
Dean
Title: Re: New battery setup (was RE: House Batteries boiling)
Post by: Dean & Dee on December 04, 2012, 12:28:19 pm
More info. I have checked the charging voltage from the alternator to the Isolator at 1500 RPM...it is 14.73V Then at the start batt's I read 13.85V at the house batts...13.87V.
Should I crank up the voltage to read 14.5ish v at the batterys?
Dean
Well I answered my own question by cranking the alternator voltage up to 14.55V at the start batteries. I am getting about 15.4V at the isolator. The house batteries are reading the same as the starts. Dean
Title: Re: New battery setup (was RE: House Batteries boiling)
Post by: Neal Pillsbury on December 04, 2012, 03:00:05 pm
............................Before I make any changes I will fire up the coach and recheck the charging voltage. With the old batteries it was reading 13.9V at 1200 RPM. So it should be closer to 14.7V ? When I set up the house charger for the new AGM house batteries I believe it's set for 14.3V's..................................
Hi Dean, Most AGM's 8-hour Absorption charge rate is at 14.7 Vdc. So that is where I would set the alternator to satisfy Odyssey. I had checked your Odyssey AGM literature and it confirmed the Odyssey 14.7 Vdc. recommendation. See this link:
But you need to also follow the Lifeline Company AGM recommendations. I don't understand the 14.3 Vdc setting and I don't have your specific Lifeline AGM battery literature, so be sure to have Lifeline recommend an alternator setting as well. If it is something less than 14.7, you need to discuss Alternator vs. Charger settings with Lifeline and use an alternator setting that is appropriate to both battery banks, even if it is slightly less than optimum for the Odysseys. Your 0.9 Vdc battery isolator voltage drops across the isolator diodes is very typical and indicates that the isolator is "healthy and working ". Let me know if I can be of any further help. Neal
Title: Re: New battery setup (was RE: House Batteries boiling)
Post by: Dean & Dee on December 04, 2012, 03:18:42 pm
Hi Dean, Most AGM's 8-hour Absorption charge rate is at 14.7 Vdc. So that is where I would set the alternator to satisfy Odyssey. I had checked your Odyssey AGM literature and it confirmed the Odyssey 14.7 Vdc. recommendation. See this link:
But you need to also follow the Lifeline Company AGM recommendations. I don't understand the 14.3 Vdc setting and I don't have your specific Lifeline AGM battery literature, so be sure to have Lifeline recommend an alternator setting as well. If it is something less than 14.7, you need to discuss Alternator vs. Charger settings with Lifeline and use an alternator setting that is appropriate to both battery banks, even if it is slightly less than optimum for the Odysseys. Your 0.9 Vdc battery isolator voltage drops across the isolator diodes is very typical and indicates that the isolator is "healthy and working ". Let me know if I can be of any further help. Neal
Thanks Neal. I really appreciate your input. I still have a call into Lifeline on a couple of issues, one being the 14.3 setting. I had the feeling while talking with the tech that he was a little "rushed". I have the alternator bumped up to 14.55 at the Odysseys posts. I will ask them if I should bump it up to the 14.7V's. The other issue I am trying to get an answer on is the battery temp coefficient setting on the house charger. The current setting is at -11.66mV F which was for the gels but it does not correspond to anything in the Prosine literature. It says the setting for a generic AGM should be -31 I believe but Lifeline said they thought it should be much less than that. He was going to check with an engineer. I think the MV is millivolts but not sure and I don't know how critical the setting is so I have not engaged the charger until I know it's correct.
It sure isn't like changing flashlight batteries is it! :))
Dean
Title: Re: New battery setup (was RE: House Batteries boiling)
Post by: Dean & Dee on December 04, 2012, 03:54:26 pm
Hi Dean, Most AGM's 8-hour Absorption charge rate is at 14.7 Vdc. So that is where I would set the alternator to satisfy Odyssey. I had checked your Odyssey AGM literature and it confirmed the Odyssey 14.7 Vdc. recommendation. See this link:
But you need to also follow the Lifeline Company AGM recommendations. I don't understand the 14.3 Vdc setting and I don't have your specific Lifeline AGM battery literature, so be sure to have Lifeline recommend an alternator setting as well. If it is something less than 14.7, you need to discuss Alternator vs. Charger settings with Lifeline and use an alternator setting that is appropriate to both battery banks, even if it is slightly less than optimum for the Odysseys. Your 0.9 Vdc battery isolator voltage drops across the isolator diodes is very typical and indicates that the isolator is "healthy and working ". Let me know if I can be of any further help. Neal
Well, the plot thickens. I just got off the phone with Lifeline and now they are telling me that the alternator should be set at 13.8V's and leave the house charger at 14.3V. The reason he say's is that because the house charger is 3 stage it will drop voltage as it charges of course, and the alternator is going to push a steady voltage of whatever it's set at.
He also said it makes a difference how many miles a year the coach driven or on alternator charge. The more miles (hours) the lower the voltage setting should be.
He could not help with the temp coefficiant. Grrr. So I am going to try calling Xantrex/Prosine and see what they say. Dean
Title: Re: New battery setup (was RE: House Batteries boiling)
Post by: wolfe10 on December 04, 2012, 04:19:31 pm
Dean,
His answer make sense-- the longer the charge time (engine running) the lower you want the voltage to minimize over-charging. Two alternatives:
Wire your alternator output as I did-- alternator output and chassis battery to one side of a marine ON-OFF switch, house battery to the other side of the switch. If you want the alternator to charge both battery banks, turn switch ON. If you were plugged in all night and are driving today and plugging in tonight, leave the switch OFF. Why burn extra diesel to work the alternator harder to OVERcharge the house bank?
The other option is what we did on the boat-- fit a smart regulator that is settable and follows the same three stages of charging as a smart charger.
His answer make sense-- the longer the charge time (engine running) the lower you want the voltage to minimize over-charging. Two alternatives:
Wire your alternator output as I did-- alternator output and chassis battery to one side of a marine ON-OFF switch, house battery to the other side of the switch. If you want the alternator to charge both battery banks, turn switch ON. If you were plugged in all night and are driving today and plugging in tonight, leave the switch OFF. Why burn extra diesel to work the alternator harder to OVERcharge the house bank?
The other option is what we did on the boat-- fit a smart regulator that is settable and follows the same three stages of charging as a smart charger.
Brett, His answer made sense to me too. The problem as you know and like Neal said is finding an appropriate medium for both start and house batteries from the alternator. I believe you may have a good solution for that issue in your post. I like the Smart Regulator option because it's install and forget it more or less. The Lifeline tech asked me if the alt. was a staged charge because obviously it wouldn't be an issue if it was. The switch option would work but it's one more thing for me to remember to do.
Of course another option would have been to go with start batteries that would be happy with a lower rate of charge.
Thanks, Dean
Title: Re: New battery setup (was RE: House Batteries boiling)
Post by: Barry & Cindy on December 04, 2012, 06:54:32 pm
We approach alternator volt setting differently. We set our Prosine charge profile so it tracks the battery manufacturer recommendations as to Bulk/Absorption & Float voltages at various temperatures. Since our alternator is not an intelligent charger and does not reduce voltage at higher battery temps, I set the alternator charge voltage to a compromise of lower than float at midpoint on temp scale. I cringe when I see too high voltage for battery temp while we are driving. I use the alternator as a source of supplying driving 12 volt needs and only as a battery charge device that can do no harm.
We have the variable alternator voltage regulator where we can change the voltage with a small screw driver without removing the alternator or regulator.
Title: Re: New battery setup (was RE: House Batteries boiling)
Post by: John Haygarth on December 04, 2012, 11:20:47 pm
Dean, I did not get to computer today to try and answer your question but it has already been done. I changed the setting af alternator when I got my agms after reading Wyatts article on what he figured out on his. I turned mine down to 13.6(had a b--ch of a time trying to set it due to being upside down, and I have trouble getting into awkward positions) for driving as I use solar mostly and that is custom set by AMSOLAR for my Lifelines (bought them from AM). I almost never charge by Inverter as it is hardly on, and mine is only set up for flooded or gell so changed it to flooded. Hopefully all will be ok and reading your Techs comment and Barries I think it will be fine. John H
Title: Re: New battery setup (was RE: House Batteries boiling)
Post by: Roland Begin on December 05, 2012, 12:00:14 am
As I have solar panels I prefer not to have the alternator messing with my house batteries. Guess I'll have to do the switch thing that Brett suggested unless there is another way to take the house batteries out of the alternator loop. I am also experiencing some "issues" with my alternator it doesn't always charge as it should, kinda bounces around sometimes at 12v sometimes at 14v (per the dash meter), it is something that just developed and I have added on my "to do" list.
Roland
Title: Re: New battery setup (was RE: House Batteries boiling)
Post by: wolfe10 on December 05, 2012, 08:38:11 am
The marine ON-OFF switch is by far the simplest solution.
Mounted on the kick panel under the front of the bed, it is easy to access if you need it.
It REPLACES the battery isolator, so alternator output is no longer used to create heat (those large fins on the diode-based isolator are to dissipate the heat).
Unless we have been dry camping and I want the alternator to recharge the house battery, the switch is OFF (house battery not being overcharged all day when driving).
The switch also serves as an excellent manual battery combiner for both charging chassis battery and as a boost switch.
Title: Re: New battery setup (was RE: House Batteries boiling)
Post by: Dean & Dee on December 05, 2012, 09:01:15 am
The marine ON-OFF switch is by far the simplest solution.
Mounted on the kick panel under the front of the bed, it is easy to access if you need it.
It REPLACES the battery isolator, so alternator output is no longer used to create heat (those large fins on the diode-based isolator are to dissipate the heat).
Unless we have been dry camping and I want the alternator to recharge the house battery, the switch is OFF (house battery not being overcharged all day when driving).
The switch also serves as an excellent manual battery combiner for both charging chassis battery and as a boost switch.
After sleeping on it I think I like the simplicity of the switch too verses having to monitor/setup another 3 stage charge system. I assume all that's involved is moving the house side of the isolator to the marine switch and then jumper between the isolator post and the on side of the switch.
Man, I never would have thought that these heavy duty highly touted Lifeline batteries would be so fussy about charging. They want no more charge rate than a gel cell. Go figure. Dean
Title: Re: New battery setup (was RE: House Batteries boiling)
Post by: Dean & Dee on December 05, 2012, 09:42:52 am
His answer make sense-- the longer the charge time (engine running) the lower you want the voltage to minimize over-charging. Two alternatives:
Wire your alternator output as I did-- alternator output and chassis battery to one side of a marine ON-OFF switch, house battery to the other side of the switch. If you want the alternator to charge both battery banks, turn switch ON. If you were plugged in all night and are driving today and plugging in tonight, leave the switch OFF. Why burn extra diesel to work the alternator harder to OVERcharge the house bank?
The other option is what we did on the boat-- fit a smart regulator that is settable and follows the same three stages of charging as a smart charger.
After re-reading your post Brett it looks like you are saying that you completely eliminated the isolator? Dean
Correct.
Alternator output, sense wire and wire to chassis battery all together on one side of the switch. House battery to the other side.
Here is the switch: PERKO Inc. - Battery Switches - Medium Duty Battery Disconnect Switch (http://www.perko.com/catalog/category/battery_switches/product/150/)
VERY KISS Theory (Keep It Simple Stupid)
Title: Re: New battery setup (was RE: House Batteries boiling)
Post by: Dean & Dee on December 05, 2012, 09:52:07 am
Alternator output, sense wire and wire to chassis battery all together on one side of the switch. House battery to the other side.
Here is the switch: PERKO Inc. - Battery Switches - Medium Duty Battery Disconnect Switch (http://www.perko.com/catalog/category/battery_switches/product/150/)
VERY KISS Theory (Keep It Simple Stupid)
Yep, the same switch I put on my boat. And Yes, I am a fan of the KISS way of thinking and that's why I got so frustrated with this battery situation as it should have been simple...... Thanks, Dean
Title: Re: New battery setup (was RE: House Batteries boiling)
Post by: John Haygarth on December 05, 2012, 10:09:03 am
Actually Dean I still think that the new batteries are not causing you the problem it is the cheaper ones for start that are. The lifelines are charged at higher rating than Gells and they can handle the temps and cold better than gells, and hold charge longer too. The switch idea of Wolfe's is a good way to handle any problems but after I reduced the alternater constant output I do not think there is any issue now. Mind you as I said I use solar to maintain them and that is all taken care of by the controller so I do not have to worry about chargers . Note-- If I have the first part of this statement incorrect please correct me so I know--
Title: Re: New battery setup (was RE: House Batteries boiling)
Post by: Dean & Dee on December 05, 2012, 10:28:03 am
Actually Dean I still think that the new batteries are not causing you the problem it is the cheaper ones for start that are. The lifelines are charged at higher rating than Gells and they can handle the temps and cold better than gells, and hold charge longer too. The switch idea of Wolfe's is a good way to handle any problems but after I reduced the alternater constant output I do not think there is any issue now. Mind you as I said I use solar to maintain them and that is all taken care of by the controller so I do not have to worry about chargers . Note-- If I have the first part of this statement incorrect please correct me so I know--
Actually John the starts are about as good as I could buy. They are Odyssey PC1500 military spec batteries. Two of them replaced the three Yellow top Optimas that I had with more CCA's. The issue is that Odyssey says their batteries need a full 14.7V's from the alt. to be happy. The Lifeline tech's tell me that their GHP 8D's should only get 13.8V's from the alt. Hence the thinking of pulling the house out of the alternator loop.
Dean
Title: Re: New battery setup (was RE: House Batteries boiling)
Post by: Dean & Dee on December 05, 2012, 10:58:25 am
I just spoke with the owner of the battery shop where I purchased the Lifelines and Odysseys. He is calling the Odyssey tech's and engineers now because he say's he sells hundreds of those same Odysseys every year for plow trucks, hummers, Army National Guard trucks, etc. and not one of them is set up for 14.7V alternator output.
His thinking is that I should be able to set the alternator voltage at 13.8 to 14.0 and the starts and house would be fine. Will be interesting to see what he finds out.
Dean
Title: Re: New battery setup (was RE: House Batteries boiling)
Post by: Paul Smith on December 05, 2012, 11:27:43 am
This is what AM Solar told me in 2007 about my concern about my alternator charging at 14.2v:
"Do you know exactly how high the alternator charges the batteries and when you say extended periods is that a couple of hours or 10 hrs? Depending upon the actual voltage that the batteries get to It's not likely to hurt them to periodically push them to, lets say 14.4 for most of the day. I just called Lifeline. Their take on it is that it's not ideal to essentially float them in the 14V range but done periodically they don't feel that it's an issue. They told me that they have a lot of their batteries in long haul trucks. The batteries are not lasting as long as they would under ideal conditions but apparently the truckers are getting about 3 1/2 years out of the batteries after driving almost every day, often all day. You could certainly install a disconnect switch to shut off the alternator charge."
best, paul
Title: Re: New battery setup (was RE: House Batteries boiling)
Post by: Neal Pillsbury on December 05, 2012, 01:37:45 pm
Dean, Well, while I was jotting this down, several others have put in good thoughts. But since I've got it all assembled, I'll chime in again too.
Welcome to the complexities of battery charging (and the results on diminished battery life cycles, if improperly managed). One of the reasons that I've appreciated the original FT engineering decision to use Optima Red Tops and MK Gel's, is the fact that while not identical, both battery sets are nicely compatible with the Heart Inverter/Gel Cell charger profile (both when I'm on AC with the Boost Switch closed or when I am on the unintelligent alternator). As long as I keep the alternator adjusted for 13.8 to 14.1 Vdc output, I'm in good operating conditions (14.1 when the start battery and house batteries are fully charged, or 13.8 when the start and house batteries are at 50% SOC and the alternator is working hard). I use the boost switch to occasionally bring the Red Tops up to full charge. As long as I follow these simple rules, nothing gets overcharged or (equally and highly important) neither bank gets routinely undercharged. I did install a "Trickle Start" to ensure that the start battery bank doesn't get neglected through forgetfulness, but remember that the "Trickle Start" device also has two major limitations associated with it (very limited charging current flow and a diode drop voltage of roughly 0.9Vdc), so it's not the answer for bringing a start battery to a full state of charge.
In your case, you have two AGM battery banks with a bit more divergent charging requirements: 1. Your Odyssey start battery bank technical literature calls for a reference (77 F) 14.7 Vdc absorption charge (not to exceed 8 hours at a time). But it also strongly cautions against routinely undercharging at 14.2 Vdc or less, which the same Odyssey literature shows will reduce useful battery life cycles by 2/3rds or more. 2. Your Lifeline house battery bank literature calls for a "Normal/Room temperature/25 C/77 F" reference point of 14.3 Vdc absorption charge. But most importantly, they strongly caution against exceeding the 14.3 Vdc at the 77 degrees F absorption charge profile. 3. Both AGM battery sets have temperature compensation profiles, but, at roughly -24 mV /degree C change from 25 C [77F], the Odyssey temperature compensation curve is a little less steep. What that means is that as battery temperatures increase above 77 F, the divergent curves become worse for you. 4. The Lifeline's temperature compensation charging profile is roughly (-31 mV/degree C). The temperature compensation changes the Lifeline absorption charging voltage from 13.95 Vdc for a 110 F battery to 15.78 Vdc absorption charge voltage for a 0 F battery.
I'm not sure what I would do in your current situation. · Of course, you're on the right track in trying to get firm recommendations from the respective manufacturer engineers. Make sure that they are answering your exact situation, however. You have two charging sources, individually applied. One is a three step profiled source and the other is fixed voltage source. · If you keep your battery isolator as installed and go with your alternator and your house charger set to the reference 14.3 Vdc Lifeline AGM charging profile, their technical literature says that you will degrade the Odyssey bank because, even with the boost switch closed, the Odysseys will see less than their optimum absorption charge voltage. That will eventually "staircase" the Odysseys down to poor starting capacity. · If you go to 14.7 VDC with the alternator output, to treat the Odysseys correctly, you definitely should follow Brett's advice and manually interrupt current to the Lifeline house batteries whenever the engine is running (or insert an intelligent step charger between the alternator and the Lifelines). · If you feel extravagant, there are a number of intelligent battery charge/isolation managers that are much more expensive and sophisticated than simple diode based isolators. They allow different, precise tailoring of the charging profiles for each of multiple banks of batteries, multiple Voltage/Current/State of Charge readouts and failure prediction warning capabilities, they do not have diode voltage drop disadvantages, they have Mil Spec pedigrees, are widely used in military, "upper crust" Marine & RV applications and, from my perspective, violate a whole host of KISS principles. · Of course sticking with one battery manufacturer, whether AGM, Gel or Wet Cell simplifies things greatly. BTW, like Paul says and unless you are contemplating returning one set of batteries, you have some time to figure things out. I have seen FT owners that, either through lack of knowledge or by choice, have run wet cell start batteries with Gel or AGM house batteries (or vice versa) for years with the FT installed battery isolator. Eventually the most abused link in the chain fails, but it takes a considerable amount of time. Wet cell vs. Gel cell characteristics are about as far apart on the abuse spectrum as one can get, and yet they somehow survive together for long periods of time. Your differentials are much smaller and as long as you don't overcharge (14.3 Vdc at the 77 degrees F absorption charge profile) the Lifelines with your AC charger profile, you're not hurting anything in the short term. Best Wishes and keep the FAITH. Neal
Title: Re: New battery setup (was RE: House Batteries boiling)
Post by: Dean & Dee on December 05, 2012, 01:41:09 pm
Okay, I just got off the phone with an engineer from Odyssey who told me that the 14.7V's is too high to use for just starting. Thats the charge rate they would use for deep cycle use. He says 14.2 is fine for their battery and of course is within 1/4V of what Lifeline would like.
Now, as far as the isolator goes, he said to be loosing almost a full volt is nuts and I should get rid of it. His suggestion is a product from Perfect Switch.com called a "Powergate Duel Rectifier" He claims there will be no voltage drop and much better charge rates delivered to each battery bank.
If anyone has any experiance/feedback on the Rectifier please let me know. For now I am going to drop the alternator back to 14.2 and do a little more research on this gadget.
Thanks, Dean
Title: Re: New battery setup (was RE: House Batteries boiling)
Post by: wolfe10 on December 05, 2012, 02:02:03 pm
Dean,
The .7 VDC or so loss across the diode-based isolator is ONLY important from a theoretical efficency standpoint (you are burning diesel to work the alternator a little harder to turn part of that extra work into heat that is dissipated by the fins of the isolator).
Since the alternator sense wire is on the BATTERY SIDE of the isolator, the batteries are getting exactly the voltage you prescribe. Yes, the voltage on the alternator side of the isolator is higher, but no battery manufacturer should have any interest in anything but the voltage AT THE BATTERY.
BTW, both manual switches and solenoid-based isolators have zero voltage drop across them. There are a lot of coaches with solenoid-based isolators with the "both" signal coming from an ignition hot source. BIRD relays are a more sophisticated example of solenoid-based isolators.
Title: Re: New battery setup (was RE: House Batteries boiling)
Post by: Dean & Dee on December 05, 2012, 02:06:48 pm
Neal, I think we were posting at the same time. I appreciate your very thorough and well thought out post. Pretty much says it all as far as my battery dilemma goes. ??? I concur with you that there are several ways to approach this for the short and long term but none appear optimum as yet.
I do feel a bit better with the Odyssey engineer telling me it is unnecessary to have 14.7V's to the start batteries, in fact he said with the loss of a volt at the isolator it would be pushing the altenator too hard and would certainly shorten it's lifespan.
Now, I have not eliminated the thought of seeing if my battery guy would exchange one or the other for a more compatable battery combination. I think both these manufacturers are excellent companies with a great product, but they are just different enough to become an issue when combined for this type of use.
Thanks again, Dean
Title: Re: New battery setup (was RE: House Batteries boiling)
Post by: Dean & Dee on December 05, 2012, 02:19:51 pm
The .7 VDC or so loss across the diode-based isolator is ONLY important from a theoretical efficency standpoint (you are burning diesel to work the alternator a little harder to turn part of that extra work into heat that is dissipated by the fins of the isolator).
Since the alternator sense wire is on the BATTERY SIDE of the isolator, the batteries are getting exactly the voltage you prescribe. Yes, the voltage on the alternator side of the isolator is higher, but no battery manufacturer should have any interest in anything but the voltage AT THE BATTERY.
BTW, both manual switches and solenoid-based isolators have zero voltage drop across them. There are a lot of coaches with solenoid-based isolators with the "both" signal coming from an ignition hot source. BIRD relays are a more sophisticated example of solenoid-based isolators.
Brett, are you and Neal setting me up for a quiz on Friday? :)) I do have a another question for you, I assume (yeah, I know) that by using a battery switch, that in the event I wanted to run the furnace etc. while traveling I would want to have the switch on so the alternator would help or keep up with d.c. demand? I know the batteries would be fine for a while but I am just thinking about the senarios of utilizing your marine switch idea. And I may be overthinking it.......
Thanks, Dean
Title: Re: New battery setup (was RE: House Batteries boiling)
Post by: wolfe10 on December 05, 2012, 02:25:38 pm
Dean,
Yes, if you are running a high amp draw on the house battery such as the furnace(s), you could leave the switch to ON. Depends on how long and how many amps. If the batteries can handle the draw, let the CG's electricity recharge them that night (but, would not run them down below 50% doing that).
Title: Re: New battery setup (was RE: House Batteries boiling)
Post by: Neal Pillsbury on December 05, 2012, 04:54:15 pm
Yes, if you are running a high amp draw on the house battery such as the furnace(s), you could leave the switch to ON. Depends on how long and how many amps. If the batteries can handle the draw, let the CG's electricity recharge them that night (but, would not run them down below 50% doing that).
Dean I second Brett's response.
With your dual 8D capacity, routine use of low-current appliances (computers, dc control boards, parasitic loads) going down the road, are not going to change your house battery bank SOC (State of Charge) rapidly. If you use resistance heating devices (like a toaster, a clothes iron, AC heat strips, infra red heater) or microwaves, or motors (residential refer, furnace blower(s), exhaust fan(s), CPAP machines with humidity heaters) types of loads, then the SOC rate of change will become apparent. With reasonable care, you should easily go 8 to 10 hours of driving time without needing to start the generator (preferable to charging the Lifelines at something greater than 14.3 Vdc) or closing the manual battery isolator switch to charge the house bank via the alternator.
Sidenote: It's an interesting dilemna to have an engineer contradict his own company's technical literature. Especially when that engineer also thinks that a 0.5 to 0.9 Vdc voltage drop in a power diode is unusual and doubly so if the engineer doesn't understand that the most commonly used, most reliable, battery isolation devices are properly sized diode isolators and properly sized switches. As Brett says, he should only be concerned about what the voltage is....AT your positive battery terminals. Also, his statement about an alternator output voltage value of 14.7 Vdc overburdening the alternator begs question. An alternator's output voltage doesn't have much to do with an alternator's load. It's the amount of current that is being generated by the alternator that matters in terms of alternator load, wear and tear.
Anyway, best wishes, Dean and no. No test in the morning. Neal
Title: Re: New battery setup (was RE: House Batteries boiling)
Post by: Dean & Dee on December 05, 2012, 05:45:40 pm
With your dual 8D capacity, routine use of low-current appliances (computers, dc control boards, parasitic loads) going down the road, are not going to change your house battery bank SOC (State of Charge) rapidly. If you use resistance heating devices (like a toaster, a clothes iron, AC heat strips, infra red heater) or microwaves, or motors (residential refer, furnace blower(s), exhaust fan(s), CPAP machines with humidity heaters) types of loads, then the SOC rate of change will become apparent. With reasonable care, you should easily go 8 to 10 hours of driving time without needing to start the generator (preferable to charging the Lifelines at something greater than 14.3 Vdc) or closing the manual battery isolator switch to charge the house bank via the alternator.
Sidenote: It's an interesting dilemna to have an engineer contradict his own company's technical literature. Especially when that engineer also thinks that a 0.5 to 0.9 Vdc voltage drop in a power diode is unusual and doubly so if the engineer doesn't understand that the most commonly used, most reliable, battery isolation devices are properly sized diode isolators and properly sized switches. As Brett says, he should only be concerned about what the voltage is....AT your positive battery terminals. Also, his statement about an alternator output voltage value of 14.7 Vdc overburdening the alternator begs question. An alternator's output voltage doesn't have much to do with an alternator's load. It's the amount of current that is being generated by the alternator that matters in terms of alternator load, wear and tear.
Anyway, best wishes, Dean and no. No test in the morning. Neal
Hey Neal, Man you guys are incredible. I couldn't ask for more help with any issue than I have gotten here. I know to some it may seem like I am splitting hairs but spending that kind of money on something and then finding it's not optimal is a bit disconcerting.
Okay, rant over. So, options I am considering now:
1- I have spoken to my battery guy again, who has been great btw, and he says he will swap out the Odysseys for whatever batteries (Lifeline, Optima, etc.) that might be better suited for the useage. Up side, I may be able to match the alternator voltage to a more optimum level for both banks. Downside, I may need to go back to three starting batteries to match the CCA's of the Odysseys, which means buying another battery. He suggested the Lifeline GPL-2400T's. They are very pricy though and I wonder if the Optima Red Tops may get the job done for less money. More research....
2- Go with Bretts Marine switch idea keeping the batteries I have. Upside, it solves the voltage issue for both banks and eliminates the isolator. Downside, (slight) I have to remember to switch on and off as required.
So if anyone wants to try to lean me one way or the other, I am all ears. (or eyes)
I agree with you Neal about the engineers take on the whole thing. I believe there is a happy medium somewhere between real world experience and what the books say. And that's not to take anything away from engineers, I spent many years in commercial construction working with them and have great respect. We just saw things differently sometimes. Anyway, the input I am getting from you folks on this forum is what is making the most sense to me.
Thanks, Dean
Title: Re: New battery setup (was RE: House Batteries boiling)
Post by: wolfe10 on December 05, 2012, 06:05:01 pm
Dean,
The direction you go depends on two things:
How much dry camping you do (followed by having the alternator charge the house battery) AND
How important KISS vs AUTOMATIC you want things.
If you do mostly camping with shore power (as we do), I don't turn the switch on twice a year. Kind of a back-up.
The On-Off switch also allows easy charging of the chassis battery from your inverter/charger unless you have made other arrangements for charging the chassis battery.
Title: Re: New battery setup (was RE: House Batteries boiling)
Post by: Dean & Dee on December 05, 2012, 07:16:39 pm
How much dry camping you do (followed by having the alternator charge the house battery)
The On-Off switch also allows easy charging of the chassis battery from your inverter/charger unless you have made other arrangements for charging the chassis battery.
Brett, Like you we typically camp with full hookups although there is the occasional 2 or 3 night dry camp weekend. Not an issue there.
So does the battery switch eliminate the use of the boost switch at the dash? Or would it still work with the marine switch in the on position?
Thanks, Dean
Title: Re: New battery setup (was RE: House Batteries boiling)
Post by: wolfe10 on December 05, 2012, 08:48:21 pm
Both boost switch and manual switch ON do exactly the same thing-- connect the two battery banks through large-gauge cables.