Community Forums

chasfenwick · 08-10-2013, 07:37 PM

My experience to date has been with Airstream travel trailer, where the refrigerator runs primarily on propane when you are not hooked up to shore power. (Yes, control board still requires small amount of D.C. when on propane). But I am getting interested in Class A or C motorhome and I am seeing conventional, residential refrigerators in them. My question is, when not hooked up to shore power, would you normally be running the refrigerator from the onboard auxiliary generator or, mostly when the main engine of motorhome is running, would you be powering the refrigerator off of the chassis' DC generator, through an inverter? If the latter, about how many peak watts would the fridge draw through the inverter? If you had the standard deep cycle batteries on board, would they operate the fridge long enough to be a practical energy source during some periods of time? Finally, I don't see any "control" provisions, for how fridge is powered, so there must be an automatic switching scheme of some sort, right? Thanks.

FlyingDiver · 08-10-2013, 08:41 PM

The residential fridge runs off the coach (not chassis) batteries, through an inverter. You need to charge the batteries daily (usually), either by running the generator or with solar cells. How long really depends on the model (size) of the fridge and how many batteries you have.

There is no switching. The fridge always runs off the inverter. Most inverters used for this purpose have a pass-through feature so that when you're on shore power or generator the power goes through an internal transfer switch so the inverter is not actually operating (inverting).

chasfenwick · 08-10-2013, 08:52 PM

Interesting! ... But when you are driving down the road, the chassis alternator will charge the crack batteries, right? So they can be charged by either the aux generator OR the chassis alternator?

chasfenwick · 08-10-2013, 08:53 PM

Ha! I love this iPad autocorrect. Make that COACH batteries, not crack batteries. Geez.

BobGed · 08-10-2013, 10:02 PM

Quote:

Originally Posted by chasfenwick

Interesting! ... But when you are driving down the road, the chassis alternator will charge the crack batteries, right? So they can be charged by either the aux generator OR the chassis alternator?

Correct. Subsequent spelling correction noted.

chasfenwick · 08-11-2013, 12:31 AM

Is there some sort of indicator lamp somewhere that shows that the fridge is receiving power? Fridge in Airstream trailer does have such a feature but, of course, off-the-shelf residential fridge wouldn't. Or, there could be some sort of alarm that tells you that fridge has lost power? Like, when you have inadvertently allowed batteries to be drained.

bruceisla · 08-11-2013, 04:43 AM

Quote:

Originally Posted by chasfenwick

Is there some sort of indicator lamp somewhere that shows that the fridge is receiving power? Fridge in Airstream trailer does have such a feature but, of course, off-the-shelf residential fridge wouldn't. Or, there could be some sort of alarm that tells you that fridge has lost power? Like, when you have inadvertently allowed batteries to be drained.

Mine is a conversion ... no alarm and no external indicator (interior light comes on when you open door). Some models have door display of temperature. Ours has an add-on remote temperature display for freezer and lower unit.

az bound · 08-11-2013, 05:29 AM

In most cases when there is a residential refrigerator a larger AH battery bank and inverter is part of the package.
Most residentials max draw is 10 amps at compressor start up and drop to 2-3 amp within a few seconds.
The engine alternator is maintaining the battery bank and power is supplied to the refer through the inverter.
The length of time for running strictly off of the battery bank depends on the total amp hours available. Most residentials can easily go several hours and maintain temperature as long as they remain closed.
An AGS (automatic generator start) system is a plus for maintaining the battery bank.

chasfenwick · 08-11-2013, 06:18 AM

I saw reference to AGS feature, and now I understand what it's for. Thanks! I'm trying to catch up from missing out on motor home lore for the last 25 years.

HD4Mark · 08-11-2013, 06:34 AM

Quote:

Originally Posted by chasfenwick

Ha! I love this iPad autocorrect. Make that COACH batteries, not crack batteries. Geez.

Off topic but if your not easily offended and want a laugh take a look at this Damn You Auto Correct! » Funny iPhone Fails and Autocorrect Horror Stories

Back on topic. When we changed from the Norcold to a Samsung residential I discovered that the 110V outlet it was connected to was not on the inverter. A simple swap of wiring solved that. I changed another outlet that was on the inverter with the fridge. The one I used fed the bathroom for some reason. I could not figure why Winnebago would do that. I do understand why the RV fridge would not be on the inverter since you would want it to switch to propane and not stay on electric if you were plugged in or running the generator.

If you plan to boondock very often changing to a residential fridge may not be a good choice. We only go without power for a night or two when in transit so it works out great for us. Not just because it works so much better but also it has almost twice the capacity.

chasfenwick · 08-11-2013, 06:49 AM

Large fridge is important to us, and in motor home a QUIET generator will be also. (I've experienced the other kind). I recently looked at Thor 33SW, and the very first thing I asked salesman to do was close doors and windows, and fire up the 6 kw diesel generator, then run both AC's at low blower speed while on generator. It passed the test.