Bad battery?

[Papa-T-XRD]

So, here is the issue. My 5er is a 2016. I have two batteries hooked up correctly in parallel. I also have a battery shut off switch.
The batteries are the same size ( Deep Cycle Everstart, 29DC -845 MCA). So, the one battery showed to be manufactured in 2015. The second battery I added later was manufactured in 2018. Never had a problem with charging. I had the 5er hooked up to shore power in my building so I can run my dehumidifier. So, the other day I went into the building and immediately smelled a strong suffer smell. It was coming from my front storage (where the batteries are). I opened the storage door and could hear the 2015 battery boiling and and when I took the cover off that battery I actually seen Vapor’s coming off the battery and it was warm to the touch. Now there is a tubed vent from both batteries; existing the front of camper. I turned off everything and let everything cool. I checked voltage on both batteries and both were reading 11.3, which is low on a charge. So today I checked all the connections on the batteries, checked the converter (wfco 9865) and fuses. When I plugged the shore power back in the 2015 battery immediately started boiling and I could smell the sulfer Vapor’s. I’m thing the 2015 battery is bad? I know I will need to replace both batteries probably. Am I thinking clearly. Any opinions are appreciated.

 

[DavisK]

One thing I would do before I put new batteries in it is to check the voltage of the converter. With the batteries disconnected and the shore power plugged in, check the voltage at the battery wires to make sure the converter is not putting too much voltage into the batteries.

 

[Papa-T-XRD]

Good idea. I didn’t do that. I read if the converter is working properly it should be between 12.3 to 12.9 volts.

 

[Papa-T-XRD]

I think I was wrong on the above voltage. Mine is putting out 13.6. I looked it up again and I read. “ The converter's output is from 13.6 V to 13.2 V.”

 

[Papa-T-XRD]

I think I was wrong on the above voltage. Mine is putting out 13.6. I looked it up again and I read. “ The converter's output is from 13.6 V to 13.2 V.”

Also, I have taken out the older battery and I’m going back to one battery. I had originally installed the second one in 2018. We did dry camping then but not so much anymore. So, I have left the good battery in and have plugged into shore power. Hopefully all will charge ok.

 

[Papa-T-XRD]

So update. I did remember that we do overnight stopping and use a fan in the bedroom at night off the 12 V plug which I have a small inverter. I decided to purchase two new deep cell batteries; same size and make as I’ve used in the past 7-8 years. Theses are 114 AH each and I will be hooking them up in parallel as before (giving me a total of 228 AH). I hope these two last just as long as the last and I will be installing them in the camper tomorrow.

 

[660catman]

I’m a little late to the party but it sounded like your older battery had a short in it. Also on dual battery setups both batteries should be changed out when one fails or in your case, going to a dual setup. It is stressed a lot in my truck forum for diesel trucks.

 

[Papa-T-XRD]

Yea I went to Walmart and they just had a 2024 shipment of the deep cycle batteries come in. I purchased the same (Deep Cycle Everstart, 29DC -845 MCA). I replaced both. If they last 8 years also I’ll be happy.