2018 Forester 3011DS Coach Batteries Question

[CapnJoe]

I bought this unit used last year, I have the two batteries under the step and every time I check them (monthly) they need water. One battery seems worse than the other. Today I was doing my monthly routine - running the generator, check engine fluids, etc. I had everything off - shore power disconnected, the generator was off and the truck engine was off, I even had the house switch in the off position. I went to check the water level in the first battery and it was bubbling like it was being charged! What on earth could be charging the battery with everything off? Could it be the one battery is so low it is being charged by the other battery?
I know before doing any kind of boondocking I'm going to have to replace these batteries but I want to make sure I understand what is going on before I invest the money.
Any help would be greatly appreciated.

[Duckogram]

I suggest the liberal use of a digital multimeter. Disconnect the ground from the battery that has the ground cable attached. Let the batteries rest for 2 hours then take a voltage reading from each battery.
This table is for AGM so your flooded batteries will read slightly lower.
I got my pair of group 27 AGM’s Deep cycles from Sams.

[Hailey]

Ducky gave you a chart that will give you an idea on the state of charge which is good to know. I prefer to use the old fashioned battery hydrometer. A cheapo one will cost (I think) less than $10 at an auto parts store or maybe Wally.
You dip the tube into the battery cell and draw in the proper amount of fluid. the needle will point at a scale, note the reading and read all six cells. The directions on the hydrometer will tell you what the reading means. what i look for is all six readings to be close to each other. If one cell reads different that means a bad cell and you should replace the battery.
I usually replace both batteries at the same time because as you said - one battery might always be trying to charge the other.

[CapnJoe]

Thanks guys - I dug out my digital meter and disconnected the negative terminal. The one battery is reading 11.31 and the other 12.37. We just returned from a camping trip so the batteries should be fully charged at this point. I guess I'll be pricing out new batteries.

[CapnJoe]

So while looking for the digital meter I came across a battery load tester I had bought at Harbor Freight and forgot I had. Pulled all of the cables and tested both batteries under load. The one with the higher voltage tested as "weak", the other one went all the way to the bottom of the scale as "bad.

[kenandterry]

That’s proof positive that those batteries are done.

Depending on what kind of camping you do (Boondocking or not) will decide what kind and how much you spend getting new batteries.

Good luck.

[camaraderie]

My guess is you'll be replacing with group24 batts under the steps due to room available and height. Here's the measurements for each typical size 12V and GolfCart6V
Batt sizes in inches..typical amp hours @20hr. rate and size designation
10.75x6.75x9.38 75a/h G24 12V
12.5x6.76x9.38 95a/h G27 12V
13x6.75x9,5 105 a/h G31 12V
10.25x7.13x10.88 205 a/hGC2@6V
i

Get TRUE deep cycle batts if you plan on camping a lot without electrical hookups. Otherwise cheapo walmart dual purpose batts are more than adequate.


That said...I remain concerned by the bubbling you reported. Once you have the new ones installed...use a clamp DC amp meter to measure the amp draw on the batts with everything turned off. Clamp your positive wire to check for any big (1amp or more) draw. Next PLUG IN or run the genny and read the voltage at the battery terminals AND do the clamp reading again. You should read 13.6Volts+ and double digit amps if the batteries are partially discharged.

[Duckogram]

Yup, your batts are gonners.
The OEM batts are group 27’s.
You MAY be able to stuff 31’s in there and get greater capacity.
If you go with AGM’s you can trash the hydrometer.

[CapnJoe]

We just got back from 3 1/2 weeks in Maine and my first project was to replace the batteries. I had a hard time finding the Duracell AGM's at Sam's club, but was finally able to locate a store with two of the group 27's in stock about 20 miles away. Installation went smooth with plenty of room for the new batteries. Letting them charge overnight. Price was $158 each plus tax.

[Duckogram]

On my way back from 4 weeks in the Camden area. Very wet and cool for July. My duracell agms from sams are over 1 yr old now and zero problems.

[mharold101]

I had a similiar problem with my 2016 Forester. While checking the batteries before a trip, I noticed the water was low and there was some slight bubbling. I added some water thinking that was all they needed. But the next morning the batteries had boiled over and the battery acid drained onto my new concrete driveway making a huge stain that I can't get out.
I will not make that mistake again!

[Sunseeker16]

Your batteries are toast. I recently checked mine while plugged in at home and they were beyond warm. Even the cables were beyond warm. The water level was above the plates and they were boiling like a pot of water on the stove on high. Even when I removed the shored power it took quite a while for them to settle down. Needless to say they were shot. News 27's and all is good.

[billwww3]

How many people replace flooded with flooded batteries? What advantage can there be other than price over the AGM? More output with flooded?

Longer life? Anything?
I'm not there at replacement stage yet, but it is always just a matter of time.

[Duckogram]

Originally Posted by billwww3

How many people replace flooded with flooded batteries? What advantage can there be other than price over the AGM? More output with flooded?

Longer life? Anything?
I'm not there at replacement stage yet, but it is always just a matter of time.

As far as I know the only advantage a flooded lead acid battery has over an AGM lead acid battery is a higher tolerance for overcharging. With a charge wizard that is OEM with the PD 4000 series used by FR in most models I do not think that would be a factor. I am also under the impression that the late model units came with AGM’s anyway. Anybody* with more info on that please chime in.

[JohnandSandiOnTheRoad]

Originally Posted by Duckogram

As far as I know the only advantage a flooded lead acid battery has over an AGM lead acid battery is a higher tolerance for overcharging. With a charge wizard that is OEM with the PD 4000 series used by FR in most models I do not think that would be a factor. I am also under the impression that the late model units came with AGM’s anyway. Anybody* with more info on that please chime in.

Our 2019 2500TSF Sunseeker cam stock with 2 group 27 AGM batteries.

[billwww3]

Originally Posted by JohnandSandiOnTheRoad

Our 2019 2500TSF Sunseeker cam stock with 2 group 27 AGM batteries.

hmmm, my early 2020 3011DS Forester has flooded group 24's(i think? unsure of size) so - model specific?

[BehindBars]

Originally Posted by JohnandSandiOnTheRoad

Our 2019 2500TSF Sunseeker cam stock with 2 group 27 AGM batteries.

Our 2020 Sunseeker 2440DS came with 2 flooded cell house batteries.

[CapnJoe]

OK, it's been a while but I wanted to give an update on the battery issue. It's a long story but two weeks after replacing the batteries with the AGM's they were bad also! It took a while to get an appointment with the dealer (I have a service plan) and it took them a week to find the issue, but it was frayed wire inside a box right under where the house cut-off switch is. Dealer couldn't explain how it got frayed but it would rub against ground when the RV was bouncing around. They also found the solenoid was "wired in reverse" and corrected that.
I got lucky Sam's club accepted the batteries back under warranty no questions asked. Only problem was every Sam's club in the area is out of AGM's, guess they're sitting on a cargo ship off the California coast. Had to replace with new flooded batteries, saved a little money there.
It's been two weeks and everything is working fine in the driveway. We're going camping next week - that will be the big test, we're going to pretend dry camp one night just to see if everything continues to work.

[Duckogram]

It has been awhile but it sounds like you found the cause. You should have better service with your new FLA’s now so long as you keep them watered and charged.

[CapnJoe]

I will be watching them like a hawk! I just bought a new hydrometer and a auto-filler bottle. I'll be keeping the digital voltmeter with me all of the time.