Will running fridge off inverter while driving cause damage?

Electrical issues, both 12 volt and 120 volt
Post Reply
Knox_Gal
Newbie
Posts: 12
Joined: Wed Oct 17, 2018 8:17 pm
B190 Year: 1991
WBCCI: 19091

Will running fridge off inverter while driving cause damage?

Post by Knox_Gal »

1991 has a Norcold N300 with a mysteriously unwired 12v connector. House batteries were recently expanded to 2 parallel 79 Amp hour AGMs to facilitate lot docking, plying an 1800w Tripp-Lite inverter. I'd like to try running the fridge via the inverter while driving, but haven't been able to figure out if doing so will cause damage to the vehicle's electrical system, et al. Can you advise? Thank you.
User avatar
skater
Site Admin
Posts: 2356
Joined: Thu Mar 08, 2007 1:00 am
B190 Year: 1991
WBCCI: 13270
Location: Annapolis, MD

Re: Will running fridge off inverter while driving cause damage?

Post by skater »

The one thing I'd worry about is the draw on the engine electrical system. The fridge draws, say, 3 amps at 120 volts, while running, which is 360 watts, which is 30 amps at 12 volts. Add in losses due to the inverter, and I'd wonder if the engine electrical system can handle an additional 30+ amp draw or not. I believe these were built with high output alternators that should handle it fine, but if it has been replaced, who knows what was put in (I put in a smaller one when I did mine because it was all I could find at the time).

Unfortunately it's the sort of thing that will work fine for a while, especially with the batteries you mentioned, then at some point, if it's drawing more than the alternator can supply while running everything else, the engine will die because the voltage gets too low. So you might get away with it for several hours, then suddenly the engine might stall. How many hours that is depends on a ton of things:

1. Is there enough capacity with the current alt to handle the load, especially considering the fridge probably isn't running the entire time? If so, then it would be fine indefinitely, in theory.
2. If not, then it would depend on how much the fridge has to run, and how much 'over' capacity the alt would be, and the capacity of the batteries (all three in this case). That's a lot of variables, and the first one in particular is going to vary from trip to trip.

I've tried to do this in our trailer, and I can tell you it did a pretty good job running down the batteries quickly (within a few hours). Our trailer has solar, which you'd think would help, and there's a charge line from the truck, but it's not delivering a huge amount of current, certainly not enough to offset the draw from the fridge in this mode. I should also note the fridge in the trailer is larger, so it probably draws more power - but the concept is similar.

Any particular reason you don't want to run it on propane while underway? That avoids all of these issues. I've also run it on 120 volt mode while the generator was already running for the rooftop air conditioner - the generator has enough capacity to handle both simultaneously.
1991 Airstream B190 - bought, 2005; sold, 2011; bought 2017
1995 Airstream Excella 30' trailer

WBCCI #13270, Washington, DC Unit
Knox_Gal
Newbie
Posts: 12
Joined: Wed Oct 17, 2018 8:17 pm
B190 Year: 1991
WBCCI: 19091

Re: Will running fridge off inverter while driving cause damage?

Post by Knox_Gal »

Thanks for your response. Using the inverter is a workaround until I can figure out how to wire up the refrigerator's 12v function and/or repair the refrigerator's pilot, which struggles to stay lit.

It sounds like it may be tried it for short drives, after adjusting the inverter to shut off under severe strain.

Have never run the generator while in motion; is that what you were referring to? If so, I'll give that a shot, as well.
User avatar
skater
Site Admin
Posts: 2356
Joined: Thu Mar 08, 2007 1:00 am
B190 Year: 1991
WBCCI: 13270
Location: Annapolis, MD

Re: Will running fridge off inverter while driving cause damage?

Post by skater »

Yes, running the generator on the road is what I meant.

The 12v mode isn’t awesome. Even the manual basically said not to expect much out of it. I’m not sure it’s worth the trouble.
1991 Airstream B190 - bought, 2005; sold, 2011; bought 2017
1995 Airstream Excella 30' trailer

WBCCI #13270, Washington, DC Unit
User avatar
con5
Weekend Camper
Posts: 47
Joined: Thu Aug 20, 2020 8:30 pm
B190 Year: 1998
Location: Fort Worth, TX

Re: Will running fridge off inverter while driving cause damage?

Post by con5 »

Our fridge thermostat broke so it is always running at max setting. That's fine for hot weather because it never gets that cold anyway. If your pilot won't stay lit maybe you can just set the thermostat to max? I think running it that way would just keep the flame on high all the time without ever cycling back to the low flow setting that is snubbing out the flame.

In cold weather, we just manually turn the fridge on and off again. I am a pretty good thermostat :mrgreen: most of the time...
Post Reply