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Author Topic: Rotten egg smell in battery means it's overcharged  (Read 1377 times)


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Rotten egg smell in battery means it's overcharged
« on: April 14, 2017, 04:42:26 PM »
So I was smelling the rotten egg smell and tracked it to the area of the batteries. Thanks to this forum I discovered that this was most likely due to overcharging.  I have two 100 watt solar panels on the roof of my RV to keep the batteries charged with a controller. Last summer in Montana I was hosting at a spot with no electricity.   I do not use an inverter, so I was only using power from the panels for the lights, igniters for propane water heater and refrigerator and for a charging station.  Maybe on an occasional cold morn I would tun the furnace for a short time.  Still I kept have occasions that the batteries were drained. The control unit never charged above 12.6 volts. So, I disconnected it and that solved the problem.  Now I have been traveling the southern route n the US and recently got the smell above not only on the trailer, but also in the tow vehicle. Is it possible the panels were putting a charge to the truck battery?  Should I now look into replacing all batteries  affected?  Is there something I can do, short of disconnecting the controller to keep batteries charged when I return to Montana for the summer hosting job?  If I need to replace the batteries in the trailer, I guess I should switch to golf cart batteries. How does the wiring change for that?

Kevin Means

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Re: Rotten egg smell in battery means it's overcharged
« Reply #1 on: April 15, 2017, 12:17:33 PM »
First, welcome to the RVForum. I hope we can help with your battery issue. It does indeed sound like your batteries were overcharged, a process that can boil the battery's water off, making them useless and, as in your case, REALLY smelly. Unfortunately, when that happens, the batteries are pretty much toast. Were you routinely checking the water levels in your batteries?

Remember, nothing in your RV is actually running directly off your solar panels. Your panels are simply an alternate method of recharging your batteries. Your 12 volt appliances are still just running off your house-batteries.
If you're sure that your solar controller was only outputting 12.6 volts, then it wasn't working. From where did you take your voltage measurement? 12.6 volts is the voltage of a fully charged 12 volt battery. The output of a solar controller, or a converter's charger, should be around 13.5 volts (give or take) so they can force amps into the battery-bank.

Our solar controller monitors our battery's voltage at all times, and can detect when another charging source is present (Converter or alternator.) The solar controller will automatically throttle back and allow those other charging sources to have priority, so the batteries aren't over-charged. To the best of my knowledge, that's how all solar controllers work.

I've never heard of a correctly-installed solar controller allowing solar panels to over-charge an RV's properly maintained house-batteries, much less the chassis batteries. When driving, the house and chassis batteries are tied together via some sort of battery management system, but there are some differences in the way some of them work.

Two 6 volt batteries must be wired in series to get 12 volts out of them, while two or more 12 volt batteries will always be wired in parallel. Sorry, I don't have a wiring diagram handy, but you can find a lot of them online.
« Last Edit: April 15, 2017, 12:20:56 PM by Kevin Means »
2011 Winnebago Tour 42QD
Towing a Jeep Rubicon Unlimited LJ
RVI Brake 2, Minder TM-66 TPMS, 960 watts of solar
(Can't wait to spend more time RVing)
Lakeside, California