I have recently purchased my first class A. A 2001 Monaco Night DP. The previous owners installed a residential refrigerator. My questions are ones that I know has been discussed before. But I am still kind of confused as to what I need to do.I have 4 6 volt batteries that provide 400 amp hrs. 200 usable. The rig also has a Xantera 1500 watt modified sine inverter. I tried plugging the frig into the inverter and although it ran when the frig kicked on and off the inverter board flashed and other lights flickered. I guess my inverter does not like my frig. Other things like the tv and micro seem to work ok on the inverter.Should I get a 2nd small inverter to run the rig or upgrade to a pure sine inverter. The frig is a Whirlpool WRT 108FZDW02. I have had some difficulty finding the specs as to energy usage.We are not boon dockers but would like to stay a couple of nights here and there and plan on doing some Walmart overnights. Will the inverter/charger keep the frig going and charge the batteries enough while traveling? I know I can turn the frig off but it would be nice to not have to while traveling and an overnight stop. I do understand any extended off grid time will need the generator to recharge the batteries. Solar may be in the future but not now. I will also want to use a laptop and charge a couple of cellphones.I am also looking at a Victron battery monitor. Any advise on which model would be best for my use would be helpful.So, should I upgrade to a larger (maybe 2000 watt) PSI or get a small one for the frig and if so what size? Will the rig run the frig/inverter and keep the batteries charged while driving? Will my 200 amp hour batteries run the rig for a couple of day if we boon dock some.Thanks as always

Forget it. The amount of money you will have to spend to run the fridge off of batteries won't be worth it, More Batteries$$ , Lots of solar$$ Etc. There are some low voltage electric fridges available but again more $$. You can of course run your Genny a lot, Please park away from other campers. Happy Camping.

my fridge is set to run on 120 v ac. the batteries are only keeping it cold while traveling.

We installed a residential refrigerator two years ago. It is similar to yours but is 10 cubic foot capacity. Using a Kill-O-Watt meter, I measured the power draw when running at 100 watts and the multi-day average draw at 40 watts. Per the Home Depot Energy Guide label for your unit (411 kwh/year) your average draw should be on the order of 47 watts. If your running duty cycle is similar to ours, your running power draw should be around 120 watts. A key consideration is the startup surge drawn by the compressor. The compressor in our unit is labelled by the manufacturer at LRA = 11 amps (or about 1,320 watts, Locked Rotor Amperes). The inverter should be sized to supply this surge, not just the running watts. I selected a 1,500 watt AIMS pure sine wave inverter dedicated to the refrigerator for our application. During our last camping trip, the AIMS stopped working. Since we were at a campground with electric power, I simply unplugged from the inverter and plugged into campground power. A first project this spring will be to replace the inverter.

i ran 7 yrs full time with a residential fridge and inverter powerit seems everything 'you have' is working as it shouldyou can expect lights to flicker/dim/flash .. what ever.. when a load starts up or stops. especially the fridge compressor startingyou may need to replace the house batteries, if this really troublesomesay IF the TV shuts off, when the fridge comes oni would advise running the generator in the morning during breakfast & mealsi would not depend on battery power alone for (2) solid days of dry parkingbut (4) batteries should be a good balance for your intentionsmany people do overnight stops with a residential fridge and only (2) batteries

You really need sine wave of at least 1000 watts to run a residential fridge.I would replace what you have with 1500 or 2000 watts.

Inverter with residential refrigerator | Good Sam Community

pianotuna
Nomad III
Jan 01, 2019
atsrmf,

Duty cycle is the pits on ammonia at 2:3, so for every hour it runs for 40 minutes. Per day on electric, the tiny unit in my class c uses 5.7 KWH. Demand when running on shore power is 325 watts if voltage is 115. When mine dies, I'll replace it with something residential for 1/5 the cost that uses far less energy per day, which doesn't have to be leveled to work properly.
atsrmf
Explorer
Jan 01, 2019
Buy a good ammonia refrigerator and be done with it. It will run on propane or 120 volts, probably drawing less than 5 amps with a/c. Here is a good link www.youtube.com/watch?v=cy1W-uWvR9U
Mile_High
Explorer
Dec 31, 2018
On our coach, the residential refrigerator option (20cf) only increased the Magnum inverter to 2800 watts from the standard 2000 watts, so I don't think your 1500 should be having any issues unless it is also running several other items.

Our 2800W Pure Sine Magnum with 6 31 series AGM 12V batteries powers our 20cf 3 dr fridge, our 80 Liter Dometic fridge/freezer in the basement, convection oven, and anything else I throw at it. I think we have even run the fireplace. I don't think I've ever actually seen it overload.
Acampingwewillg
Explorer II
Dec 31, 2018
Relying on not so perfect means of determining Voltage while driving down the road, both my Chassis and House batteries are in the 14 volt area. Now, I did just upgrade my alternator to a 250amp model because of other inverter loads I have on while traveling...hence the other reason I shut down the inverter when parked. Any length of Boondocking is not in my future!!
larry_cad
Explorer II
Dec 31, 2018
I've been running a 10 CF residential frig with my 2000W Magnum mod sine invertor for several years, including while driving down the road. Actually ALL the time. No problems thus far. I cannot comment on the Xantrex except that I personally do not like Xantrex from previous
Bill_Satellite
Explorer II
Dec 31, 2018
theoldwizard1 wrote:
DrewE wrote:
Since this is a class A motorhome, it undoubtedly has from the factory a pretty decent house battery charging setup from the chassis already ...

How did I miss the fact that it is a Class A !

I am curious to know on newer Class A or Class C, just exactly what is the house battery voltage when running down the road. Anyone want to do a test ? Give a good 10-20 minutes of drive time.

My Class A maintains 13.5 V the entire drive despite the inverter and fridge running. I have a 90 amp alternator on the engine so the batteries are fully charged at all times.
theoldwizard1
Explorer II
Dec 31, 2018
DrewE wrote:
Since this is a class A motorhome, it undoubtedly has from the factory a pretty decent house battery charging setup from the chassis already ...

How did I miss the fact that it is a Class A !

I am curious to know on newer Class A or Class C, just exactly what is the house battery voltage when running down the road. Anyone want to do a test ? Give a good 10-20 minutes of drive time.
DrewE
Explorer II
Dec 31, 2018
theoldwizard1 wrote:

The other big question, is this RV going to be used for boondocking on a regular basis or only occasionally. If only occasionally (like Walmart camping on the way to a destination), then a DC-DC charging system would also be a good investment so that the tow vehicle can properly recharge the house battery bank.

Since this is a class A motorhome, it undoubtedly has from the factory a pretty decent house battery charging setup from the chassis already (and, of course, no seoarate tow vehicle). A DC to DC charge system may be an upgrade, but I suspect not an especially pressing one.
theoldwizard1
Explorer II
Dec 31, 2018
pianotuna wrote:
No smaller than 1500 watts pure sine wave, with a 'quality' inverter/charger.

Go all the way ! Get an inverter/charger/transfer switch. No worries about turning the inverter on and off. Much easier to wire and you can get rid of the converter. Just wire the DC fuse panel directly to the battery bank.

pianotuna wrote:
You might consider turning the inverter off overnight once the fridge is not going to be opened, until morning.

But if you do not open the refrigerator all night, how much does energy does it really consume ?

The other big question, is this RV going to be used for boondocking on a regular basis or only occasionally. If only occasionally (like Walmart camping on the way to a destination), then a DC-DC charging system would also be a good investment so that the tow vehicle can properly recharge the house battery bank.
Bill_Satellite
Explorer II
Dec 31, 2018
A lot of "you must" information from folks who very likely don't have a RR in their RV and never would.
The 1500W MSW inverter should power your fridge without any issue at all. You may want to look at how the wiring is setup between the battery and the inverter (long run and/or small wires?) or the health of your batteries. 400 AH in a true deep cycle battery bank should be more than enough if charged properly and the batteries are healthy.