Automatic Transfer Switch

1L243 wrote:

BFL13 wrote:
"On a sunny day my solar can produce as much as 26 amps and I think my refrigerator only about 8/10 amps. "

My 6cu ft Norcold pulls about 350w on 120v so that is about 35 amps DC via inverter. I had lots of solar but it could not keep up with the fridge, even at high noon. Gave up on that and now leave the fridge on propane after trying that.

You would only slow down the draw on the battery by running the fridge on inverter with whatever amps solar is doing at the time. A few more amps via 7-pin would help if only they were at the same voltage as the solar, but it would still not be enough to supply the fridge's inverter draw completely.

I know the refrigerator uses alot of amps on startup not sure what my number is but much less once the refrigerator reaches cold. Then it depends on how much you access the fridge and maybe how hot it is outside. It could go hours before it cycles on and off while traveling.

Down the road I may add a 40 amp DC to DC charger.

Like I said I usually run the refrigerator on propane when towing if there is too much of a draw and it starts to drain down the batteries I will switch it back to propane.
It will still be nice to have energized outlets when stopping for lunch or a break without having to go outside and plug into the Inverter.

Absorbsion RV fridges (that can use propane or 120V) do not have any startup surge. Instead they use a little resistance heater module which can range from 275W to 325W at 120V depending on fridge size. So unlike a home fridge conversion you do not need to figure in for startup surge.

The downfall of using 120V AC instead of propane in an absorbsion fridge is that 120V heater uses three times more power than if you simply swapped out to a home fridge.

325W at 120V is 2.7A, run that through an inverter that turns into 27A at 12V not including inverter losses. Inverter will have about 80% or a bit more efficiency so add in an extra 2A at 12V or roughly 29A.

Compare that to a home fridge conversion, if you watch you can find 10 cu ft apartment size home fridges that draw about 90W at 120V or .75A. That .75A would convert to 7.5A at 12V without inverter loss which would be around 1.5A for a total of 9A at 12V. A much more reasonable power draw.

The startup surge for all intents and purposes do almost nothing to use up battery capacity even though they are on the order of 8x the run current because the startup surge lasts for only a few microseconds. You do however have to plan for the surge upfront with thick enough wire and a inverter above 1,000W.

Your throwing good money at this for no real good reason other than to not use propane. If the propane operation while moving is a problem, then fix it. Generally propane operation while moving is not a problem. I personally never had an issue with propane operation while mobile and the fridge I had was a manual pilot light! Even during a severe storm with 60 MPH microburst straightline winds hitting the fridge side while driving.

Otherwise, if it is you simply do not like propane at all, swap the RV fridge for a home fridge conversion.. My current TT, we did a home fridge conversion, just one pair of 6V GC2 batteries powers everything we use including the fridge for 24hrs without the need for solar or a generator..