Fried my batteries


New Member
Recently we drove our Coach on a week end outing. I smelled 'rotten eggs' and assumed I had a holding tank leak. Upon checking I observed the coach batteries were hot and overflowing battery acid. We continued our trip and the chassey battery gauge went down to 0 and the motor started missing out etc. I hit the booster and it began to run again. The gauge returned to normal and the coaches batteries quit emitting gases and returned to normal as well. Does anyone know what happened? Also after returning home it seems all of my batteries went totally dead after sitting 2 weeks. The coach is a 95 Thor Residency 35footer. I assume some switching thing messed up and fried everything? Coach batteries are 28 months old and chassey battery 6 months old. Please help and thanks


Senior Member
Re: Fried my batteries

Well for one thing, make sure you neutralize that acid before it eats through your motorhome :dead:

First of all, take readings across the batteries to ensure that the charge voltage is correct (under all conditions, motor running, generator running, both running, neither running and not plugged in, plugged in).

Next take all the batteries out (making sure to label where all the wires go). Mix up some baking soda and water and spray it everywhere acid could have gone. When it stops fizzing, clean it real good, and if there is any bare metal, spray it with some 'rust be gone'. This stuff will convert any remaining rust to a primer like coating. Primer any remaining bare metal, and then apply the best paint you can find. Wipe down the outside of the batteries with the baking soda mixture.

Now test them. Make sure they are all filled (using distilled water) and charged (external charger is best for this if the charging voltage above was not correct). I'd use both a load guage which will tell the overall condition under load, and a hygrometer to show the status of each cell. If they are bad or marginal, replace them. 2 weeks to totally dead doesn't seem very good, unless there is a significant drain on them. If there are no 'memories' (like in the engine or transmission or entertainment center) which need to be maintained, use or add battery disconnects to avoid parasitic drains. If there are such memories, consider solar or some other method of keeping the batteries charged without risking lowering the fluid to damaging levels.

Replace and rewire the old and new batteries. I might see if there was some kind of monitor I could hook in to alert me if this situation happens again. Temperature or Voltage would seem the most practical choices.


Senior Member
Re: Fried my batteries

Sounds to me like one of two things happened. Either you voltage regulator went haywire or your battery had some dead cells in it. Check the output of your alternator and have your batteries tested. And do what John said to clean up that acid.


Senior Member
Re: Fried my batteries

While the advice so far is not bad, this does not sound like a problem that will be easy to solve if you have no real knowledge of electricity. Do you own and know how to use a multi-meter? Cleaning up the acid is a must item and do it soon. It could be that the voltage regulater was acting up and if so it will probably happen again. You need to know what happened before you buy new batteries or you will probably destroy them too.