I recenty moved from a class B to a small fiver. My old van had one deep cycle battery and I installed an isolator. This set up was good for several nights of light usage before I had to run the van to charge the battery. My new trailer seems to use a LOT more power. Granted, it has an electronic start fridge, rather than a constant pilot light as well as the furnace and a propane monitor(the old van was a 1982)I still think I should get more than 3 nights of use off a battery charge. We used very little light, no water heater, no fantastic fan and only 2 or 3 cycles on the furnace per day. We dry camp 90% of the time and I intend to purchase a generator for now and solar when we retire in a couple of years.I beleive we will have to charge fairly often, maybe daily.....but I don't want to be one of THOSE GENERATOR A##()&Les! who need to run their generator for hours at a time disturbing everyone's peace and quiet. I'm looking for a max 1 hour charge time. I have a smart battery charger that will charge at 2, or 10-20 amps as well as an onboard IOTA convertor that has a 750 watt input @120 v that will put out 45 A at 12v. My local dealer sez the convertor really will only charge at 5 amps or so. He also sez deep cycle batteries should be charged very slowly for best effect.Is my best bet to install a starter battery rather than a deep cycle on the trailer and charge it heavily and quickly? I recognize the best set up is to go with solar but can't justify the cost yet.Thanks all for your anticipated input.Turnkey

Stay with a deep cycle. Problem is that you probably don't have one now. Most dealers install a combination starter/deep group 24 marine battery which isn't a deep cycle battery.The furnace most likely is your heaviest load. If you run heat all night a group 24 battery will last one night. You probably have an LP detector and possibly a CO detector that is a constant draw. With the refrigerator you might have a drain of 1 amp per hour or more.The typical group 24 combo battery has 80 amps. Just the basics are likely draining 24 amps per day without running lights, fan, or furnace.The answer is to have more batteries and charge once per day for a couple hours. You don't want to regularly drain the battery more than 50%. Many of us use 6 volt golf car batteries because they give more amps per dollar.Use the IOTA, it is a good charger especially if you have the charge wizard.I see you have been a member of the forum for a long time. These subjects are discussed regularly. I suggest you spend some time on here and do a lot of reading. The wealth of knowledge on this forum is amazing.Read all three pages of this;http://www.marxrv.com/12volt/12volt.htm

Your best bet right now is to change to 6 volt golf cart batteries and a lot of them. Find a place to install at least 4 golf cart batteries. This joule give you at least 4 or 5 days of use with no furnace. Last year we camped for 4 days in cool weather. Meaning cloudy, one rain showers and the furnace on a lot. Using only my solar panels I was able to go the whole four days and only use the generator once the last day for a couple of hours. And YES your fifth wheel is a power hog compared to older RV's. everything takes power now days from the refer to the smoke detector to the gas sniffer. Heck I can remember back in the old days you could leave your car sit for months go out and hit the starter and it would crank. Try that today with the newer cars. All those computers take energy to keep running.

Your power useage is not out of line at all.If your converter only charges 5 amps, JUNK IT !IOTA and charge wizard are not compatable.4 6v golf batteries in a small 5'er is rediculous !2 6 or 12v deep cycle batts will do you just fine, but you will need a 35-45 3 stage converter, and a little generator running 1-2 hrs a day, depending on your needs. But if you run that forced air heater, along w/ the other needs, figure on charging 2 hrs a day.....w/ a good 3 stage converter/charger.

TURNKEY wrote:I still think I should get more than 3 nights of use off a battery charge. TurnkeyMy experience would argue that 3 is pretty good if your using a type 24 battery - when it gets colder you won't even get that - consider buying bigger battery +/or more batteries.

If you're boondocking that much I would concur with getting 6V's. I would also switch out your most used lights with LEDs. I switched all of the interior lights in my old 5er to LEDs. Went from 350W total draw to 87W (all lights on).RJsfishin wrote:4 6v golf batteries in a small 5'er is rediculous !LOL! What's ridiculous about it? There are tons of people here with 4 6V's in their 5ers. I had the same 740 amp hour bank in my old 5er that I do now in my MH. It all depends on how you want to camp.

Deep cycle or starter battery charging issues

59 Replies

westend
Explorer
Dec 27, 2013
Thanks for the update. Yup, solar is the best.
TURNKEY
Explorer
Dec 27, 2013
The Tristar charge controller has a desufation/equalization mode as well as temperature compensation. I keep my batteries nicely mixed even during 6 months of winter storage in the house. It also allows charging at a high enough voltage for long enough that I do often get to 100% by noon. Realize we often will only use 10-20 amp hours over night. We do not have an inverter and ALL lights are LED. The solar system I have will charge at over 11 amps if the batteries drop to allow bulk charging. Also with the Trimetric I continually increased the 100% set point as the batteries improved in their efficiency and had several days of no draw solar to top them off.100% is 100% (note I am using the 50 amp shunt not the 500 amp for the Trimetric as we have no inverter so my accuracy is 10 times what most folks would have.)
BFL13
Explorer II
Dec 26, 2013
Glad things are working out, and thanks for the follow-up so we can all learn something about what works or not.

However, no way are you getting to 100% every day on solar. Maybe 98%. You still need to get the batts to 100% on shore power every so often (usually every one or two months to not lose capacity)

I suggest if home now for a while, you do a complete desulphation routine on your new batteries if it is not already too late. Even if you lost some capacity from as rated new, at least you can stop it there and get years more from them.

Don't get confused by the Trimetic's idea of "full" which is really somewhere you are invited to pick as a setting that is less than 100% full. It is a very useful tool, I love mine, but you have to be aware what is really going on with it so you don't get bamboozled.

When you camp when too cloudy for solar to keep up, you will be glad you got that genny! :)

There is no need to disconnect the truck when on solar. Leave both on and whichever has the higher voltage at the time will do the charging. One does not "kill" the other and sometimes they might even add their amps.
pianotuna
Nomad III
Dec 26, 2013
Hi,

You could have saved on the big wire from the panels to the controller, but I'm glad it works so well for you. Temperature compensation really works well, too.
TURNKEY
Explorer
Dec 26, 2013
As an update, I went with 200 watts of solar on the roof, 2 Costco Golfcart batteries, a Tristar charge controller, BIG wire all round, ALL Led lights (super cheap from china) and the Trimetric meter. I upgraded my old IOTA 45 amp converter with an IQ4 module which makes it a 3 stage charger now and got a Honda 2000.

The experience? UNBELEIVABLE!! We NEVER run the generator!!! The solar gets me to 100% by noon most days. I have totally disconnected the 12 volt system from the truck as I can get more off the roof than from the truck while towing. Big props to Handy Bob.
BFL13
Explorer II
Mar 20, 2013
If your charger will stay at 14.8 until battery voltage reaches that, then you can do no more. Mex is talking about when the charger has a timer that drops its voltage too soon before battery voltage rises enough and the SG catches up too, even when accounting for "SG Lag" before dropping to Float.

If your solar array is not enough in wattage to supply enough amps during daylight (so not enough AHs), you will not get to a full charge if you used more AH than that previously.

Every day is different due to cloudiness, etc, so you can't pick a number that will work every time for how many AH to use and how many watts of solar you need for replacing the same number of AH every day so you get to a full charge every day.

You go camping with what you have and adjust as you go along as required to get by, including running the gen powered charger when solar can't keep up. Max flex.

OP has enough to go camping and find out how that goes without losing all 12v at 3 am. After each trip, lessons learned, adjust set-up. Ten years later it might be getting close to being right :) ( But then you get a new rig and start over)
TURNKEY
Explorer
Mar 19, 2013
Mexicowanderer, I didn't get a couple points.

"If a person is using a solar system to recharge the the panel limitation does not allow the 14.8 to raise cell gravity to 1.265 daily"

Why not? If the panels are putting out 18 volts, controlled down to 14.8, then delivered by short runs of heavy wire, for a period of sunshine sufficient to deliver the amps lost?

"and the 2% of amp hour capacity top-charge will be rapid"

2% ?? Did you mean 20%?

Trying really hard to get this stuff figured out.
Randall
westend
Explorer
Mar 18, 2013
I just installed a similar sized solar system and am upgrading with another bank of 2-6V GC2's. I chose the Sunsaver MPPT-15 controller for a few reasons. First, Rogue is not selling their new controller yet and I'm unable to wait. Second, Morningstar's reliability as expressed by users. Third, the capability of programming and data logging with a serial interface to a computer. The serial interface and software does all of what the Trimetric does but is not as handy as looking at a monitor. I've installed a couple of analog gauges so that I can see what's happening at a glance. Fourth, price, I bought the small MPPT controller for $200, a lot less than it's bigger brothers.
Thanks to all the members that have helped with my solar installation and advised me on the pertinent details.
MEXICOWANDERER
Explorer
Mar 18, 2013
The 14.8 voltage bulk charge regimen is correct. Hearing that the Morningstar is fully programmable is great news. Balance 14.8 voltage TIME with what you see on a hydrometer, and it will be possible to tweak the time at 14.8 to obtain a rational level of charge before reverting to float. With a generator, the limit is money for fuel and regulations for run time. With solar it is the amount of time the sun is up. If a person is using a solar system to recharge the the panel limitation does not allow the 14.8 to raise cell gravity to 1.265 daily, more panels are called for to allow the 14.8 to be reached earlier in the day. The school of the hardest knocks taught me this formula as the on being the one most rational for systems that are confined to solar only charging. 14.8 is the maximum I allow for daily charging. There will be a little "over-run- after the 14.8 rate is terminated in which the batteries will still be "charging" (this is a chemical process, remember?). When the batteries revert to "float" the batteries should be at 1.265 corrected.

This formula allows for infrequent top charging, every 10 days or so, and the 2% of amp hour capacity top-charge will be rapid, just a couple of hours, to 15.0 volts. This should minimize the need for equalization.

Of course winter solstice requires a different regimen then summer solstice but then you can figure out the other ten thousand permutations.
TURNKEY
Explorer
Mar 18, 2013
When I cook I am a COMPULSIVE pot stir-er.

The Trimetric is to help me deal with my 'control' issues.

Yeah..when I relook at solar charge controller issues probably a SUNSAVER would be enough, I just want to ensure I have temperature compensation and can get the charge rate up near 14.8 volts.

I'm not planning to increase the truck-trailer charge circuit at this time. I recognize it would be a great opportunistic charge time but first I want to be able to be self suffiecient in the campground. Besides with my back up camera I'm already at 2 umbilicals, and to do a good job wiring I would bypass the 7way and run a seperate umbilical, taking me up to three!

Thanks for the input all.
Randall

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Deep cycle or starter battery charging issues

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