Tuesday, March 21, 2023


How can I add an inverter to power my refrigerator on 120-volt while on the road?

Dear Dave,
We have had our unit for several years, mainly using it for coast-to-coast travel. Our Dometic (N7XR) fridge uses LP gas or generator/shore power for operations. I have wanted to install an inverter to power the unit on the road. The coach has two batteries, as does the chassis. Thor has a schematic/diagram to install an inverter into the main breaker panel. After many calls, and them sending various PDF’s for our unit, I still cannot locate the one needed. This is the only way to bypass the use of LP while on the road safely unless, of course, the fridge is off.

Another question: Is there a way to repair a cracked fridge bottom pan or is replacement of whole unit necessary? If replacement is necessary, is it possible a 3-way replacement could be installed? Our RV repair facilities are very slow, at 6 weeks just to get unit in for troubleshooting, and an extended time to repair at about $200 per hour. Ouch! Any help would appreciated. Thank you. —Richard, 2018 Thor Synergy SP-24

Dear Richard,
We have been working on a 2015 Thor Challenger, which is a Class A and has an 1800-watt inverter to power the residential refrigerator. I have to say that Thor’s wiring diagrams leave a lot to be desired. Guess I’m spoiled by the diagrams and 3D views available on Winnebago’s website. Here is what I got from Thor.

The inverter was located in a driver side compartment near the front. I believe you may get more information from the inverter company.

Should be easy to add inverter

It should be easy for you to add an inverter into the system, and I would suggest the Xantrex model 1800. Your refrigerator is plugged into a typical 120-volt outlet in the back compartment that should be accessible through the outside vent panel, since you have an absorption refrigerator.

This outlet is wired to the distribution panel, as seen in this photo. You should have a circuit breaker dedicated to the refrigerator at the distribution panel, as well. So, providing 120-volt power to this outlet via the inverter can be accomplished in one of two ways. In both cases you would need to disconnect the 120-volt wire from the distribution center and wire it into the 120-volt output of the inverter.

Battery connection only

The fastest and most simplistic connection is to run a 12-volt source from the battery to the inverter. Then either plug the refrigerator cord into the front outlet of the inverter, or pull the panel off and run 120-volt wiring to the refrigerator outlet.

This front panel outlet can be removed and the unit hard-wired to the refrigerator outlet, as the panel usually cannot be located close enough to plug the refrigerator in directly.

120-volt pass through

The second option is to wire the 12-volt from the battery as shown earlier, but also wire a 120-volt source coming from the distribution center to the inverter as a “pass through” option. This means if the RV is plugged into shoreline power, the 120-volt power will pass through the inverter to the refrigerator outlet and not draw down the battery.

That is how the unit in our Thor Challenger is wired.

The 12-volt DC wires on the back of the unit come from the house battery bank, and the 120-volt wiring comes in from the distribution center, and out to the outlet. The 120-volt outlet was removed from the front panel and a RJ11 plug goes to the LED readout inside the rig.

Note: I would recommend getting a certified electrician to run the 120-volt wiring in either case, but there is quite a bit of prewiring and installation you can do yourself.

As for the refrigerator pan, can you remove it? If so, you could do a plastic weld if it’s just cracked. Otherwise, a 2018 should still have parts available unless there is a supply issue. Another option would be to replace it with a 12-volt compressor driven one like Everchill or Norcold that will draw about 1/2 the house battery power, as your refrigerator going through an inverter is a 12-volt hog!

 You might also enjoy this from Dave 

Can I run my RV’s refrigerator on 12 volts while driving?

Dear Dave,
Can’t I run my RV’s refrigerator on 12 volts while running down the highway and turn off my propane tanks completely? —Fil Patrick Peterson

Read Dave’s answer.

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

Read more from Dave here


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1 month ago

If all you want is a means to keep the frig cold while you are on the road, assuming this is a one day’s drive between hook ups, you might consider those blue ice packs. We keep several frozen on hand and distribute them in the frig, keeping it closed during the day’s haul. We freeze them again that night while plugged in. We track the frig’s internal temperature and this works nicely for us when traveling no further than 350 miles in a pull. I prefer not to run appliances while in motion.

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