Why does RV fridge stop working after awhile even when plugged in?

Dear Dave, 
We are getting my parents’ motorhome ready for them to visit and live in this summer and we are having some issues. After losing power to the fridge and TVs, we thought maybe the batteries were bad so we replaced the house and engine batteries. (The engine batteries were 6 years old so we did them, too.) Once we replaced them and plugged into shore power, the fridge and TVs powered right up and stayed on for several days, but by the following weekend, they had gone back out and wouldn’t come back on. We checked the house batteries and they both said “weak.”

After researching some of your Q&As, we are starting to think the converter might be bad. However, one issue that persists is the radio in the cab of the truck. It will NOT turn off. It defaults to demo mode if not in radio mode. We confirmed it is connected only to the house batteries.

Hoping to not have a bad converter

I’ve read that the Pioneer radio could have this issue of not turning off if it’s wired incorrectly to the 12V source. If that is the case, would we see our house batteries drain to “weak” even if the rig was plugged into shore power all week? I think not, because shore power should be charging them, but I’m just really hoping to not have a bad converter!

Thanks for any help you can offer! —Debbie, 2015 Thor Four Winds Super C

Dear Debbie,
Unfortunately, it seems as though your converter/charger is not providing 12 volts to your house batteries. The first thing I would check is the circuit breaker at the distribution center.

120-volt power is supplied by the shoreline cord, and one circuit breaker is typically dedicated to the converter, which charges the house batteries. The converter can be located alongside the distribution center, such as in the photo above. However, most larger units will have a separate “standalone” converter hidden under cabinetry or even the bed.

Set of fuses may be blown

There is also a set of fuses on this type of converter that may be blown.

Since you have a Super C, it might have a larger inverter that would also charge the battery instead of a converter. Looking through used RV sites, I do not see a listing for an inverter, so it is hard to tell which charges the batteries.

I did see it lists the refrigerator as an absorption refrigerator running on either LP or 120-volt power. So that also indicates a loss of 12-volt power, as the refrigerator needs 12-volt power even when running on 120 volts to power the control module and thermistor, which is the temperature sensor.

What is draining the batteries?

The dash radio is not the only component using 12-volt power when the unit is in operation mode. The LP leak detector, interior lights, water pump, roof vents, and any appliance running on LP use 12-volt power. You can check your batteries with a simple multi-meter. With the unit unplugged, the batteries should read 12.6 volts when fully charged. Plug the shoreline cord in and either the converter or inverter should provide 13.6 volts with low batteries, or 13.2 volts constantly in maintenance. Anything lower than that means you are not getting a charge from the converter or inverter.

Since the unit is almost 10 years old, I would assume the original batteries have been replaced at least once and that they or the second set got drained so low that the converter or inverter ran full time at 13.6 volts, which is not good for longevity. The inverter also has a set of onboard fuses that I would check, as well.

One option is to use a BatteryMINDer

If the batteries are drained below 11 volts, the interior lights would still work but would be dim. One option would be to use a BatteryMINDer^® that charges and conditions batteries with high impact waves so there is less gassing of the batteries. I have a friend that decided to buy a $100 version of that rather than a $300 converter and has been using it for three years. The issue with that is the unit will be running 100% of the time and typically would not last that long. The same thing would go for a typical battery charger, which would also run 100% of the time if the batteries will not hold a charge.

So the radio is not the only drain, but it can be shut off by pulling the fuse it is connected to.

 You might also enjoy this from Dave 

How can I tell if my converter is charging?

Dear Dave,
I noticed that my house batteries do not seem to be charging when I am plugged into power in a campground or at home. I replaced them this spring and am wondering if the inverter/charger has gone bad, or could it be something else? How can I tell if my converter is charging? —Gregg, 2016 Winnebago Sightseer

Read Dave’s answer.

Dave Solberg is a leading expert in the RV industry and the author of the “RV Handbook.”

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