Alternate power source and elec. fridge questions

[Vickie B.]

If I put in an electric fridge (in place of the 3 way Dometic), do I have to do anything special---does this need vented??

Also, if I'm not using propane appliances, can the battery power an electric heater and the fridge?

Thanks!

[Ken C]

off the top of my head i am thinking about all those little electric fridge's in hotel rooms that aren't vented. Someone on here has done it but I cant remember who to link you to the thread.

For battery power, then your converter, then the heater, You could get the amp draw on the side of the converter. That would be my starting point. Then try to add up all the amps of the other two appliances. In other words, I would personally run the numbers as a first step. On a side note, I have ran a fridge on battery power before and it sucked down the battery very fast. They now have efficient tundra 12volt rv fridge's out now that are very nice, but expensive.

[pbraunton]

the battery alone will not do either of these let alone both at the same time, ........

well they will but not for long, maybe a few hours, ..........

running a heater takes a lot of power, ............frdige as well but not as much as a heater

I am sure someone will pipe in with some numbers to run though it with you, but it won't work, ....

do you have a 3 way fridge your trying to get rid of?, I would be interested in it if you are, .............send me a PM

thanks

Paul

[Vickie B.]

Paul, I'm still trying to decide----could not get the fridge to cool lower than 45-50 degrees on the last trip. (Using electricity.) Seller advised I try it on propane---he had no problem getting it cold last summer.

Still haven't decided if I want to mess with propane.

I'll let you know if I decide to take it out.

Vickie

[GeorgeR]

Originally Posted by Vickie B.

If I put in an electric fridge (in place of the 3 way Dometic), do I have to do anything special---does this need vented??

Also, if I'm not using propane appliances, can the battery power an electric heater and the fridge?

Thanks!

To help digest your question here is some math.
24/27 group battery could have let’s say 75 ampere-hours usable capacity which at 12 volts is about 75x12=900 watt-hour, this means you can run the battery at 900 watt drain for an hour.

An electric heater at 1000W will drain usable capacity in 54 minutes (60x900/1000=54) running full time and less than 2 hours running at 50% duty cycle. I think that an electric heater is out of the question.

Small compressor refrigerator is about 60 watts (5 amperes at 12 volts) and it will drain the battery in 15 hours (900/60=15) full time and in 30 hours at 50% duty cycle. To run a refrigerator an 85W solar panel with a good 24/27 group battery or equivalent should be OK. Refrigerator needs to be vented and 50 inch^2 for inlet and outlet opening vent is recommended - Norcold_Manual .

Running both at the same time will consume battery in about 51 min.

Good luck,
George.

[pbraunton]

thankd george i knew the numbers didn't work out but didnt know the exact math of it!!!

Paul

[Vickie B.]

I really should have paid more attention in math and science class! Didn't see the relevancy of it back then

Thanks guys!

So I need to embace the use of propane, buy the quietest generator possible, or only camp where electricity is available------------------

[Per Walthinsen]

Originally Posted by Vickie B.

I really should have paid more attention in math and science class! Didn't see the relevancy of it back then

Thanks guys!

So I need to embace the use of propane, buy the quietest generator possible, or only camp where electricity is available------------------

Hi Vickie:
I have done the conversion this year, replacing a Dometic RM2333 with a NovaKool R4500 (12v only), and here is what I've found:
This NovaKool uses about 3.7 Amps (can be set up to run slower or faster with corresponding current usage) and cycles, so that is not a steady draw. I gained about .8 cu feet of space, but mainly the unit is much more capable in hot conditions, keeps the set temperature VERY accurately and is utterly quiet (in fact I cannot tell it is running without going outside and listening through the vent).
That kind of draw will bring my two group 31 batteries down to between 50 and 60% in 48 hours, so I added a 100W solar panel with an MPPT controller. When parked among heavy Oregon trees it will not replenish the draw, but if it is out in the open and sunny it will run the frig and add to the charge very nicely.
My old Dometic had gotten terribly frustrating, with frozen vegetables at night and more than 50 degrees in the daytime. That's history now.

[Ray N]

I think that our small Norcold compressor fridge works at no more than 25% duty cycle. But it is a tiny one so we always augment it with a good old-fashioned ice chest.