Rv battery problems

[Trbo323]

So, while I went camping lots as a kid and into my teens, my wife and I bought our first camper last year, I'm still learning all the maintenance things for it.

We have a 2011 Coleman e3. It's a pop up camper with a cargo deck on the front, pretty unique little design.

We have a camping trip coming up in a few weeks and I figured I would open up the camper and my daughter and I slept in it on Friday. Earlier in the day I plugged it in to shore power. In the evening I turned the propane on and about an hour later my wife said she smelled propane around the camper. I went to investigate and knew right away that it was not propane but there was a smell of sorts. Started looking around and as I'm doing so I put my hand on top of the battery box. It was warm. Fairly warm. Only one box though (I'll call it battery A for reference), the camper has been modified to hold 2 batteries (stock is only one).

Got the box open and found the battery in it was actually hot. Not enough to burn my hand but wouldn't be comfortable to hold it either. So I disconnected battery A and set it off to the side figuring something happened to it. Connected the wiring back on to the remaining battery (battery B) figuring that would get us through the night only to find that that one had exactly 0 output.

Battery A is a sealed design so I can't open it up. Battery B is standard flooded. I opened up one lid which covered 3 chambers and found exposed plates in one chamber. Opened the other side of 3 chambers and found one chamber that had milky acid and some metallic bits floating in it.

Now, it seems to me that both batteries are probably toast at this point but I'm trying to figure out what exactly happened. When battery B had something happen to both chambers did that then affect battery A?

Im going to go get 2 new batteries, found a good deal on some "factory second" AGM batteries so I think I'm going to do that but want your opinions on if you think my campers inverter could be a problem.

I should mention, both batteries A and B are older, A is from 2016, B is 2018, they are not a matched set, one is group size 27 the other is 31, from different manufacturers.

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[martix_agent]

Never replace only one battery, always replace all of them at the same time because a battery going bad causes extra stress on the other batteries.
If the battery was getting hot, something failed internally; it's possible that the water level was low because it wasn't maintained properly, leaked, evaporated, or just wore out. 2016 an even 2018 are getting pretty old and it may have just worn out.

[Trbo323]

Never replace only one battery, always replace all of them at the same time because a battery going bad causes extra stress on the other batteries.
If the battery was getting hot, something failed internally; it's possible that the water level was low because it wasn't maintained properly, leaked, evaporated, or just wore out. 2016 an even 2018 are getting pretty old and it may have just worn out.

That was kind of my thought as well.

Just to be clear though, the battery that was getting hot was NOT the same battery as the one I found low on water

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[XEMON]

That's to be expected, the one low on water will not do anything ...

[Melrosejedi]

Camper batteries have a rough life as they dont get used and charged as much as they should. Both batteries should be identical in flooded or sealed composition if hooked together in camper charging and output system. Amp output should also be the same. I would start with new batteries and check charger output on each battery when camper is plugged in. When stored in the winter hook a trickle charger on them to keep the voltage steady. Good luck and have fun camping,as i do.

[XEMON]

Are the batteries in parallel or in series?
It will have a drastic change in how they charge and behave.

[Trbo323]

Are the batteries in parallel or in series?
It will have a drastic change in how they charge and behave.

Parallel. 12v the ones I'll looking at are around 100AH each

Speaking of though. The AH rating seems to be all over the place in some cases. Most of the good batteries I've been looking at are around 100, some at 105 and some cheap ones at 80. Optima of course has a $1000 150AH battery but that's kind of expected from them

Then every once in a while I'll find something like a $120 orilies basic flooded that says it has a 650AH. I'm kind of assuming that's not true, maybe they missed a decimal point?

Here as an example, napa cheapie but says it has 408 AH

https://www.napaonline.com/en/p/BAV317238

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[XEMON]

There are different types of batteries.
Starting battery (like you have in your car to start the engine) have very high output current, but they are designed for short usage. 5-600 amps is standard, called cold cranking amps (CCA). But those batteries are not handling well a slow discharge like we use in RV ...
Slow discharge battery may be labeled "wheel chair" battery. They will not have the hounf to crank an engine, but they handle slow discharge over time.

It is common for description to mix CCA and AH ...

Ps: in my van built I put golf cart battery. They are usually 6v, but put them in series and you get a 12v battery bank 👍

[BrickHaus]

My best guess is that when your dead flooded battery lost enough cells, your good battery was being pulled down to charge it in essence. Thats totally a speculation.

Now that being said, your rv should have an internal battery charger that juices those batteries when it's plugged into shore power. You may have a charger issue to troubleshoot.


You want deep cycle batteries for your rv. These are also called marine batteries. I'd buy a pair of them that match at this juncture.

All glass mat media helps with your battery handling rough rides, but they are a bit more costly.

Do you happen to have a friend or family member that goes to Costco? You can likely get both batteries for much cheaper through costco. I just got my membership, but I recall hetting a kirkland battery via my dad years ago. It was a 130 dollar battery every else. It was 89.99 at costco.

[Trbo323]

Ok, got batteries, long story short I found a place near me that sells factory seconds. So, ended up with a pair of unbranded group 31 gel batteries.

I believe these are the same battery just as a factory first

https://defender.com/en_us/gel-tech-deep-cycle-marine-battery-group-31-8g31dt?srsltid=AfmBOori5CPaP18ofhd8ZJJyOIFXGWyQPdVZhP-6DHttJJONsPeRZU7NiO4

All the stats match and the casing with the exception of the carry handle is even the same. The nice thing though is I paid $180 for each.

I decided on the gel batteries after talking with the guy there, while the AGM batteries would work, I don't need the CCA and the gel batteries seem to have a longer life at lower draws.

So those are on the camper and it is currently registering 12.77v so they are basically full

Now, before I go plugging into shore power, anyone have any recommendations on how to go about testing my inverter?

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[XEMON]

What type of inverter you have will determine exactly how to test it, but a simple voltage check of the battery when plugged in and not plugged in will get you started.
If both batteries are in parallel you will not have any monitoring or load balancing ...

[martix_agent]

Trbo I went through this earlier in the year when I also needed batteries for my RV.

The NAPA one you're seeing is a "marine battery" I'm guessing, that is able to output very high amperage to start engines. If it has battery posts like a car and lists cranking amperage, you don't want it for you RV. You want the ones with screw holes because they're not rated for cranking amperage and will last MUCH longer. Actually, they say that 6v forklift batteries are some of the best to buy because they're built for extreme abuse and charging cycles. The problem is that you have to buy double of them to keep the amp hour capacity that you want. I didn't have the battery space without modification so I didn't end up going in that direction.

It sounds like what you ended up with is an actually deep cell battery, and that's a good thing. They have a much longer life. Gel batteries seem like the way to go but they're also very expensive. You can get lithium, but then you also need a new battery charger that's compatible.



To test an inverter, you have to know a little bit about the specific inverter. Does it go to "float charge" when the batteries are fully charged, OR IS IT NOT THAT SMART AND JUST TURNS OFF? iT MAY ALSO BE SMART ENOUGH TO KNOW THERE'S NOT A LOAD SO YOU MIGHT NOT BE ABLE TO CHECK OUTPUT VOLTAGE WITH THE BATTERIES DISCONNECTED, EITHER.