Run a Residential Refrigerator off the Batteries while in the Shop?

A very long story that requires a simple solution on my 2012 Thor Tuscany 42RQ.

I have to go in to the Freightliner shop in Idaho Falls to resolve a coolant issue, likely from all tests to date, a blown head gasket on my ISL 9. In a perfect world they will be able to do the R&R through the service hatch in the rear bathroom. If not, well, let's not think about an engine pull.

My dilemma is that this is a new shop and we may have some issues with providing power to the coach in the shop. Naturally, I just filled the residential refrigerator with a month's worth of supplies.

Thor conveniently located the power outlet for the refer behind it such that you would have to pull the entire thing out to get to it and attach an extension cord.

So, given my limited options, I am wondering if I can just put a 15 amp power cord to the coach power cord (I actually have the adapters), turn everything off at the breaker panel except the 50 amp breakers and the inverter, and let my batteries charge and run the refer. Typically, without generator, I can run that refer fine, and use about 20% of my battery capacity in 12 hours.

Based on my experience with this unit, I feel like the charger will keep pace with the minimal use of the refrigerator. How close am I to reality here? or is there another solution?

I'm plugged into my house right now with a 15 amp extension cord hooked up through the 50amp power inlet.
My fridge is on and I don't use the inverter and did not turn off any circuit breakers either.
I don't have much else running, but the house batteries are being charged too off the 15 amp power coming into the coach.

You should be fine if almost nothing else is turned on besides the fridge.

In my coach, this particular circuit is wired to the inverter, and that's the reason I wanted to be sure what was what to keep the batteries charged. As long as I can break even, power wise, over the course of the service stay, I'm good.

Thanks for the real world example.  8)

The Turn off all other breakers (With the possible exception of the converter.. I'd like to keep it powered too) is likely your best option.

When this RV was in the shop we only had 20 amp service so I powered JUST the converter (It's a plug in model) and used the inverter to run most of the "Stuff" in the  house (TV, Computers, support junk) had to fire up the Generator for the Microwave or A/C. Gas for Fridge and water, .

Kim, are you saying that the fridge runs 24/7 off of the inverter?  That seems strange to my limited knowledge of how they convert to a domestic fridge once you have a direct link to 110 on the RV fridge before the switch.  Was it due to having to change the wiring so that you have power through the inverter while on the road?

Ed

I would be very much surprised if that inverter doesn't have shore power as an alternate source and uses that when available. Try it at home and I think you will be pleasantly surprised.

However, to answer your question, yes you can plug to 15A shore power and let the house system maintain the battery charge for you. Turning off the breakers for unneeded circuits will help prevent unintentional overloads that could trip the 15A source breaker. Be aware, though, that the source outlet for that extension cord is probably itself one of several sharing one 15A breaker. You may not have the full 15A exclusively for to your coach.

Let me restate the point about the inverter's role. In my previous coach, not all of the AC receptacles were tied to the inverter, i.e. if you cut shore power, and did not start the generator, they were not hot.

That is NOT the case on this coach, and when shore power comes off, nothing AC drops power, even for a second, including the refrigerator or clocks.

But I understood my documentation on my Magnum to say that it was always inverting and I could have misinterpreted that. We may be saying the same thing and (no pun intended) we may not be connected clearly.

To your point about sharing the load on the 15A circuit, are you thinking it's a heavy load to run that charger?

But I understood my documentation on my Magnum to say that it was always inverting and I could have misinterpreted that. We may be saying the same thing and (no pun intended) we may not be connected clearly

Click to expand...

I'm not aware of any Magnum brand inverter/chargers that does NOT have an internal, automatic transfer switch that will pass through shore power instead of actually inverting. If you identify the Magnum model, we could verify that for you.

To your point about sharing the load on the 15A circuit, are you thinking it's a heavy load to run that charger?

Click to expand...

Probably not too heavy for the full 15A, but suppose there are half-dozen outlets sharing that one 15A circuit?  There is no way to know how much power is being consumed at the other outlets. There is no guarantee you can get 15A at every single outlet because the breaker trips when the sum total of all loads reaches 15A. Your coach may be using only 3-6 amps, but if somebody plugs a big power tool into another outlet on the same branch circuit, the breaker can still trip.

Generally the charging system uses only modest amperage because 1A of 120vac power will produce 10A @ 12vdc. Most of the time the charger is pulling only 1-2 amps from shore power. However, if the power has been disconnected for a few hours and the batteries run down somewhat, when the power is re-connected the Magnum's charger will surge to 10A, or maybe even 15A. That can trigger the breaker even though the surge lasts only a few  minutes.

The experiences of others show that relying on the shop to maintain power to the rig is rather "iffy".  Some tech pulls the plug for whatever reason and forgets to re-connect, or a breaker trips and nobody notices, etc.  YOU end up with a stinky fridge full of spoiled food, and the shop accepts no responsibility for it.

I've had good results at places that specialize in motorhome service - they usually know to keep power up. Other places, even RV dealers, can be chancey. They may mean well, but stuff happens.

I obviously misinterpreted the documentation and the transfer switch now seems obvious. Thanks for the clarification.

The shop is used to having motorhomes in, we have had a long conversation about the issue, and I will be keeping an eye out when I physically check status several times a day while we are in the shop.

In God we trust, the rest of 'em, I'm watchin' very closely....I will be managing my expectations.

Kim (skyking4ar2) Bertram said:

............., and I will be keeping an eye out when I physically check status several times a day while we are in the shop.

Click to expand...

Kim I can tell you are just what a shop manager loves to see. :

In the good Freightliner shops, that's exactly how they measure customer satisfaction and are scored internally. I have yet to have a problem with them and this one is bending over backwards to accommodate us.

Customer service does not have to be a lost art.