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Alcazar · 10-07-2013, 08:46 PM

I have coach batteries that will go flat after a short time without an outside charge connected to them. I found one of the 2 12v Interstate Deep cycle batteries had 2 cells with low water. The electrolyte was below the plate tops on 2 cells. Today I entered the RV and found a pronounced sulfur smell. I checked the coach batteries and found the one with the 2 low water cells was very hot on sides of the battery. I filled the cells and disconnected the 120VAC cord to shore power. I have the RV parked for a few days right now. I am wondering if the battery is hot because of the low water or if there is something else wrong here. How long should I keep the batteries on charge when connected to shore power and how is that controlled? I would think there is a smart charger somewhere in the RV that senses the batteries and drops to a trickle charge. Is that wishful thinking or ....?
Thanks in advance for all replies to this vexing issue. FYI I am battery familiar and have done my time on technical issues with computers but this one has me puzzled.

hochmuth1957 · 10-08-2013, 01:44 PM

Had the same problem with my old TT. Came to find out that the charger side of the magnatec had lost it's mind and was boiling the crap out of the battery. Ended up replacing the power center and the battery. There is alot of good info on this site about testing converter outputs. Look them up and then get out the old multimeter.
Electrical gremlins sometimes take a bit of effort to track down but you learn alot about your rig in the process.
Happy hunting.

Alcazar · 10-08-2013, 06:15 PM

Thank you for your reply to my post. I have some information about the electrics but not the detailed information that would be needed to test the circuits. I am able to find my way around electrical testing dc or ac with diagrams or wiring charts. I think I am at least looking at changing the deep cycle batteries due to 2 of the cells running low on water in one battery(the one that was very hot to the touch). It is recommended to replace both at the same time. I bought this MH used from a rental agency. A 2013 model with 28K miles on it 6 months ago . I have warranties and such but do not know if this is covered since it appears as neglect by the previous owner.

The Romer · 10-09-2013, 10:14 AM

It is probably the converter and its abilty to charge the batteries properly.. Go online to your converter and get the volt specs with the unit and you can see where the problem lies. Also I got the best on a new one on Ebay.. If you are getting new batteries, wait untill you replace the converter or you will ruin the new ones.. Also look into to 6Volt deep cycle ( golf cart) batteries.. last longer and will give you better service..

hochmuth1957 · 10-09-2013, 10:44 AM

I agree with the Romer. Check converter before replacing batteries. I made mistake of assuming my bat was bad and ended up destroying a new one before figuring out it was the convertor that was the problem. I would also recommend you search the net for any recalls on your converter and coach. There may some known issues that are being covered under warranty or recall.
Good luck.

Alcazar · 10-10-2013, 09:58 PM

Thank you for all replies. I will check the converter. At this time the batteries are charging at 13.2 vdc. I will check later to see if they get hot. Currently the shore power is connected to the rig. I think it is a case of neglect on the part of the past owner (a rental company) that did not check the electrolyte levels for all the cells. Once the plates ran dry the battery lost it's effectiveness and would overheat when charged. Probably damaged the battery. I have messaged the Rental company to see if they will pick up any charges to fix this. I do have an extended warranty but does not cover coach batteries.