I would like to set-up my 35 Liter ARB fridge in my Disco with a portable battery unit (Schumacher PSJ-2212). It would fit in the back of the vehicle where it would serve as an intermediary between the 12 volt car socket and the fridge, so the battery would keep the fridge running when the engine is turned off. I attached a link to a unit, but I don't know if it is big enough. What components do I need for this to work? I am not electrically inclined. I need names and pictures. Thanks.

Amazon.com: Schumacher PSJ-2212 DSR ProSeries 2200 Peak Amps Jump Starter and Portable Power Unit: Automotive

 

How much run time, with the engine off, are you planning on and what size, CCA rating, battery do you currently have?

 

I just had an Optima Red Top 35 battery installed yesterday. It is rated 720 CCA. I suppose I have the option of running a cord from the main battery to the fridge OR hook the fridge up to its own portable battery. I don't know which one would be better. I would like the portable or main battery to supply enough power to the fridge overnight (10-12 hrs).

The fridge specs are as follows: 12 V DC = 5.0 A, 24 V DC = 2.5 A, 100-240 VAC = 0.8-0.4 A, 120 VAC = 0.75 A.

 

You would have been better off with a Yellow top, but a Red will easily handle the draw from the cooler with little or no side effect on one battery, just plug into the aux. plug in the cargo area, I ran mine for years that way.
If you just have to pay that sort of money for a back up, just buy another Red Top and run dual batterys for the same money.

 

But he wants the unit to run when truck is parked and not running. Doesn't that power port drop of when key is off? Alternate you can have second sealed battery for the fridge, charge it when truck is running from the power port, and let fridge run off second battery while you are out of truck. If it does run that second battery all the way down, because you are late returning, you will have warm beer; but truck will still start from main battery. BTW, the reason the Brits have warm beer? They have Lucas refrigerators.....

 

Hi Savannah,
Yes, I do want the fridge on when the car is off. I just need to know what portable battery to use (name, power size, etc) if I do set this up as a stand-alone from the main battery.

 

Any of the sealed car batteries (or sport equipment batteries) would be fine, as under normal conditions they don't vent hydrogen gas into the passenger compartment. Like the red or yellow tops. They do make smaller ones, and a 28 amp hour might be enough - but for a few dollars more you can run a long time, plus have back up for other uses. Since they are automotive to start with, no problem connecting to the plug in power outlet. Now an interesting point, you may want to unplug from the power port when truck is "off" so the 2nd battery does not try to power things that the truck thinks are "off", or install a battery isolator.

 

That fridge, like portable gps units, may only power up when the voltage is higher than 13v that's the only way they can distinguish a running car from a turned off car. So even If you hook it to the 12.5 volt jump box it still may not turn on. (just something to check)

 

I think your main concern should be the transformer more so than the battery, unless that refrigerator uses dc current. Off the top of my head, I would use a battery charger connected to the vehicle aux outlet in the back. The charger would be attached to a battery sitting in the back. A transformer would be attached to the battery. Then the refrigerator would be attached to the transformer. The fridge would be getting constant power from the battery, and the battery would be getting charged whenever the car is running. If the battery dies out, the car battery is not affected at all.

If the fridge is a dc, then you can connect the fridge directly to the battery and connect the battery to a charger, and then have the charger plugged into the aux power in the back.

In either case, I would also make sure the fridge is really well insulated. I would also keep as much ice in there as I can. Both of these steps would lower the number of cycles the fridge would need to run in order to maintain the temperature.

Looking at that link. I don't think I would rely on a jump starter. Personally, I would just put an actual car battery in the back to power the fridge.

I have run things like that in my Caravan (years ago), and I used a car battery with a transformer attached. Worked just fine for me.

The only thing I would be concerned about is if that aux outlet would produce enough power to run a battery charger and not blow the fuse.

 

Well, being a frugal father of a soon to be college freshman, I think about how many bags of ice I can buy to put in a coleman cooler, divided into price for this fridge and battery parts. And then I consider just how many times I actually would get some use out of it.