Power pack to run ARB fridge while camping- questions

zimm17

Observer
After camping and having my ARB run my battery down too low and leaving me stranded, I don't quite trust it. Turns out the battery saver was on "low" instead of "high", but even high is 11.8v, which is 35%- too low for my comfort zone. I mostly run the ARB in my Jeep and it now has a single AGM battery.

I was thinking about getting a portable power pack to act as an energy reserve for the fridge instead of going with a true dual battery set up. When I'm jeeping, I drive everyday so it'll have a way to charge.

Simple questions- is it better to run the fridge off the battery pack on AC or DC? Can I make a charging cord for the power pack that will utilize my existing ARB power port? That has 12 gauge wire and will handle more current than the factory 12v plug in the rear. How big of a pack should I get?

The fridge pulls .85amp/hours. At least 24 hours of running on it would be nice. 2 days, even better. And then I can save the full power of my starting battery for the engine.
 

john61ct

Adventurer
The cutoff on fridges is more to protect the fridge than the bank.

Personally 200+Ah would be my minimum reco for a lead bank if a fridge is involved

for a lead bank.

120-140Ah for LFP.

If not just solar, but if frequent top-ups from a FF source or overnight mains is available every couple days

then 100Ah / 70Ah might be enough.

Stick to DC, even when on shore power you should have a high capacity charger capable of "fast charging" on top of all your load devices

at the same time
 
I built a 650 Wh (54 A-h) power supply in a tool box. It runs my Alpicool CF35 for two days w/o recharge but I have 100 W of solar, ac recharge and DC recharge available. I built LiFePO4 so I can extract 500 Wh (40 A-h) out safely. AGM or FLA equivalent to 1200 Wh. I run it on DC
 

encryption

New member
I have read that the jackery 500 runs an arb50 for 3 days. Then charges via 12v plug while driving.
Depending on the season, I just can't see that happening, I have a Goal Zero 1400 and connected to my Dometic 65L via 110 Volt connector, it won't charge it more than 36 hours in the peak of summer and that is draining the battery down to 15%. Of course my dometic was being used more as a drinks fridge than a food fridge.
 

jadmt

Well-known member
Depending on the season, I just can't see that happening, I have a Goal Zero 1400 and connected to my Dometic 65L via 110 Volt connector, it won't charge it more than 36 hours in the peak of summer and that is draining the battery down to 15%. Of course my dometic was being used more as a drinks fridge than a food fridge.
110 sucks down way faster than 12V.
 

encryption

New member
110 sucks down way faster than 12V.
I understand that, but you cannot get any efficient cooling on 12 V unless you have plugged your fridge into a wall socket and cool all your perishables / drinks down to fridge temps. You will lose your good on longer trips using 12 V.
 

NatersXJ6

Explorer
Before going down that road, I would verify that my vehicle battery was really good and being charged properly. Personally, in my JK with a 15 mile commute and 115+ summers, I quickly gave up on an Odyssey AGM. It wasn’t getting high enough voltage off the alternator to charge, it was drawing too far down, 2 days without driving was all it could take before I was in the danger zone. Being dead battery bound at 115 degrees sucks, even if you have cold drinks. I was using the fancy charger on it every 3 days whether I drove or not.

Eventually I gave up and crammed a group 27 FLA in there, I also added 2x100 watt solar panels. Haven’t had a problem since. I think I’m past a full year now, so I’ve hit every season. Combined, the panels, controller, wire, and battery barely cost more than the single Odyssey.
 

mattpayne11

Member
You could get a Bluetti EB 240 which is 2400 Wh... probably over-kill but you could run your fridge on it for a very long time without recharging the battery... =)
 

jadmt

Well-known member
I understand that, but you cannot get any efficient cooling on 12 V unless you have plugged your fridge into a wall socket and cool all your perishables / drinks down to fridge temps. You will lose your good on longer trips using 12 V.
not on an arb 50. I have run my fridge for 2 and 3 day stretches on a stock jeep battery with no issues. I know people said no but I have done it numerous times. stayed frosty cold.
 

jeepers29

Active member
not on an arb 50. I have run my fridge for 2 and 3 day stretches on a stock jeep battery with no issues. I know people said no but I have done it numerous times. stayed frosty cold.
Us as well. We used the ARB harness that runs directly from battery to frig.
 

Martinjmpr

Wiffleball Batter
If you're handy you can make your own for less than the cost of the more expensive all-in-one power boxes. Mine was about $200 all-in but that doesn't include the DC-DC charger that I installed in my truck to keep it charged up, that added another ~$150 - $200 and a few hours of my time, but I've been using it for almost 18 months now and it keeps our 12v Indel-B (Truckfridge) running just fine.

Periodically over the past year I would notice the "E1" error on the fridge if the truck had been sitting parked for a long time. But the voltage meter was showing over 12.3 V which should be more than enough to keep the fridge running (since my fridge is not connected to the truck battery I have it set on the lowest voltage cutoff setting.)

My guess is that on hot days when the compressor kicks on the voltage drops just low enough to kick on the LVCO. Either that or the electronics on my fridge are getting wonky. Considering that the fridge is almost 7 years old and has been on no fewer than 120 camping trips, bounced around in the back of multiple vehicles and subjected to extremes of heat, cold, dust, etc, I have to say we've gotten our money's worth with it.

My "power box" uses an FLA battery and is a heavy pig (80lbs) but it stays in the truck so it's not like I have to move it around much. If we did a lot of hardcore 'wheeling I'd need to have it strapped in somehow but we really don't do much more than dirt roads and mild trails so the place where it sits (right behind the driver's seat, wedged between the seat and our food box) works fine.

The most expensive single component of any battery box is likely to be the battery itself. There's a couple of ways you can go with that, either go cheap and accept the down sides of that (weight, mostly) with the idea that if the battery fails you can replace it for not too much, or go expensive (LiFePo) and treat the battery carefully so it lasts a long time.

The biggest challenge with a D-I-Y box is how to charge it from a 12v source. You can't just plug the ~60AH battery straight into a 12v "power socket" as it will pop the little fuse (typically 10a but I've seen some that are 15a) right away. So you need some kind of charging system that will regulate the amperage, like a DC-DC charger. Either that or run a set of heavy gauge cables from your starter battery into the interior compartment of your vehicle to connect directly to the alternator. Personally, I wouldn't be crazy about having a high-amp power source like that going into the cab of my truck without some serious protection. What I did was got a Renogy 20a DC-DC charger and I run a pair of 8AWG cables from my battery to the rear of the cab to the charger. The cables are fused at the battery end of course but additionally, they are connected to the battery with an RV-type quick power disconnect knob, so when I'm not running the fridge (basically when I'm at home) the knob comes off and there's no power at all going to the rear of the truck.
 

dman93

Adventurer
If you’re not interested in DIY and don’t really need an inverter and 110 AC output, there are a bunch of us who like our Dometic PLB40 batteries ... see another thread in this section. Small and light (like a 6 pack of bottles), built-in solar charge controller and DC-DC charger, and a couple of USB outlets along with the 12V out. It can be charged from solar, 12V or 110. 480 Ah capacity. Not cheap but a well-designed and practical product.
 

67cj5

Man On a Mission
What you are quoting with your ARB fridge @11.8v is the point where it cuts out, When the ARB is running and the battery is reading 11,8v once it turns off the voltage will come back up to around 12.15 to 12.25v which is about 50% of your batteries capacity and at 12.2+v it should have enough power to start a Petrol/Gas powered Vehicle so at 12.2v your battery is quite safe, When the fridge is running and it reaches 11.8v +/- it should cut off and it will not power up again until the battery has around 12.6v back in it,

If you are running a single battery always set the cut off on the Hi setting which is 11.8v, Every battery will climb back up once the fridge stops which can climb as much as 0.5v + 11.8 = 12.3v.

Hope that helps.
 
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