Why Is My RV's Charging System Boiling My House Batteries?

by Lori
(Vacaville Ca USA)

Hi, I went and prepared to go camping and the batteries were fine. While we were camping that night the house batteries died and they seem to be boiling and are now fried. What do you think the problem could be? We had a bad battery temperature sensor fixed a yr ago 2005 Alpine Motorhome

Thanks

Lori

ANSWER Hi Lori I am going to have to assume that all of your problems happened when you were either hooked up to electric or you were running your generator.

Your Battery Temperature Sensor may have gone bad again, but I am also inclined to think that your motorhome's battery charger is sending too high a voltage to your batteries or one of your house batteries has a short in it. I am not sure if your motorhome has a panel that shows a digital reading of the voltage going into your house batteries. If it does; follow the steps below to see if your house batteries are being overcharged.

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1. This step requires that the RV be unplugged from electricity. Since you state that the batteries were boiling, I am going to assume that they are low on electrolytes. The first thing you need to do is top off all of your batteries with distilled water.

2. Once you have filled up the batteries go through your RV and make sure that all of your 12-volt lights, etc. are turned off. Then go to the panel that shows the battery voltage and see if the batteries show any charge at all. If they show any charge at all regardless of how low, go ahead and move on to step 3.

3. Plug your motorhome into electricity. Take a look at the battery voltage reading. If the charger is working properly the reading should be around 14.4 volts + or - .2 volts. If the reading is too high then it means that the charger is overcharging your batteries; this also means that your battery temperature sensor did not work properly because it did not shut down the charger when the batteries were boiling.

Just a note: If the voltage reading was low; it would mean that the battery charger was undercharging the batteries.

If the charger is charging properly the first thing I would do is replace the battery temperature sensor. Once that is done, I would leave the motorhome plugged in for 5 or 6 hours and see if your house batteries accept and hold the charge. If the batteries are holding the charge they should show a reading of around 12.6 volts with the RV unplugged and without any draw on the batteries. If the voltage is any lower than that; it means that your house batteries are going bad or are already bad.

If you find that your charger is overcharging the batteries you need to take your motorhome to a qualified RV repair facility. The first thing I would have them check is the condition of your house batteries and then fix the overcharging problem. I do not normally recommend that do it yourselfer RVers start messing around with electrical converters and chargers; you should have an expert repair these items.

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Hopefully, this information has helped you resolve your charging system problem, I am going to take a moment here to recommend a video that will help all do it yourselfer RVers learn how to maintain their RV's 12-volt charging system. The video below is by RVing Expert Mark Polk and can be instantly downloaded to your computer.

Deep Cycle Battery Care & Maintenance Let RV Expert Mark Polk walk you through the step-by-step process to understanding lead acid batteries, battery ratings, battery types, sizes and configurations, battery maintenance, testing, charging, storage and more. Whether you own an RV or a boat you can watch this as often as you need, making battery care and maintenance simple to do and easy to understand

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Happy RVing

RVing Al