Rez fridge question

6 hours on a single group 29 AGM would use 50% of the capacity.

Also, are you boondocking, or looking at travel time? Your battery will get a charge from the truck while you are driving.

The reason I asked was my fiver goes to the storage lot. Currently I have the 3 way fridge and the night before we head out I go and fire it up so it cools down by the time we leave.

So that is why I asked the question of how long will it run - with real life answers and not the dealers '3 days' answer.

I would plan on getting a second battery as well and transfer the 100W solar panel I have now onto the new fiver, but that doesn't really do anything for me during the night when the sun inst shining but the batteries should be topped off come night time when I go start it up.

I do not have the option of plugging it in at home the day before or going 3-4 hours before we leave to start it up. In watching some videos it seems 8 hrs is about realistic with 2 12V batteries

You might not have to pre-chill the fridge
A residential fridge cools down faster than the lp fridge

If you turn it on and stick cold food in there
It will be cold before you make your first rest stop

Do you like math? I Do.
Look at the label on the fridge. I will use a small Dorm/Office type that sucks 100 watts running, about 500 starting.

Now you said a SINGLE 12 volt battery. This means a MARINE/rv or a MARINE/deep cycle. you can only use about 25% of the power in the battery

Group size: Amp hours. Usable watt hours (At the 20 hour rate)

24 - - -- - - 75 - - - - - - 187 so it might run about an hour.

(NOTE I use 10 volts as the battery voltage in these calculations to allow for inverter loss)

27 - - - - - 95 - - - - - - -237.5

29 - - - - - 105 - - - - - 262.5

31 - - - - - 130 - - - - - 325

4d - - - - - 230 -- - - - - 575

Now if you go to Golf Car Batteries (NOTE the numbers here) GC-2

YOu can get GC2 in the 230 amp hour size as well but you can use fully HALF of that power so now you have 1150 Watt Hours for that fridge.

divide usable watts by fridge watts to find the result.... Figure aboutr 3/4 run time to offset the surge.

Note that there is an effect. Can't recall the name (Pulket???) exactly but what it says is the faster you suck out the power the faster still the battery runs down So if you draw at the 20 hour rate you will get performance close to what I listed. but draw at the 10 hour rate and your run time goes down FASTER (You get like 1/4 the run time)

Bottom line.. Get a generator.

Another thing to consider. There is no Federal Inverter rating dept. So they can put any number on them they want. Not a problem with the high end brand name inverters, only the off brands sold here and there. Ask me how I know.

You might not have to pre-chill the fridge
A residential fridge cools down faster than the lp fridge

If you turn it on and stick cold food in there
It will be cold before you make your first rest stop

That is a possibility and I would like to find out how fast it takes to cool off, especially when its like 100 degrees inside the camper during summer.

Lwiddis wrote:
If you are going residential fridge then do it properly...four 6 volt batteries and adequate solar.

I'd also highly recommend an amp hour meter. I installed a Victron BMV-712 in my truck camper

Austinjenna,

I can tell you that a propane fridge cool down time is about 15 hours. But that is at 20 c (68 f).

Pukert is the formula for guestimating how a load causes a battery to drain.

oops, duplicate post