Arb 37 quart wiring suggestions

I just bought an Arb Fridge Freezer that I will run inside my Livin Lite Quicksilver 10.0 pup during road trips of up to 12 hours at a time. I am concerned that I will not have the necessary amperage coming directly off my tow vehicle’s (Jeep JKU) battery because of the length of the run. Arb says it uses up to 2.3 amp hrs. I plan to run 8 or 10 awg wire to the 7 pin connector. From there it should trickle charge a marine battery that will be used to power the fridge while driving and rest stops of up to 1 hour in the summer (PA/MD region).

I am looking at a Group Size 24 battery. Is that sufficient? Any other thoughts on my plan are appreciated.


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Chris Boyd

Explorer
I run a group 34 (~65 Ahr) and depending on ambient and load of contents, can run the fridge for about 24 and a bit

The average hourly load of the fridge is something like 3-4 amp Hours in my setup and mid- voltage cutoff setting, which is enough for me between engine runs. It does use about 7-8 amps pull when the compressor is running, so if you don’t ventilate the cabinet well (or have a hot interior) it will run more than they claim.

I’d go with a larger group 35 if you have the space. They more the better. Make sure you fuse both sides of the trailer connector (fuse in the trailer and another on the vehicle) for the charging, as alt/battery to battery amp flow can be quite high and you don’t want to burn up your harness cable.
 

Chris Boyd

Explorer
Oh, and whoever advise you about the long run was right. Even the rear factory cig plug in my landcruiser fused at 10amp was problematic. The high amperage on the small factory wire caused a lot of intermittent voltage cutoff issues on the fridge, even though it was rated for 10A
 

rickc

Adventurer
My massive Dometic 75litre fridge ran for 36 hours in fridge/freezer mode at an ambient temperature of 70C fed by a group 31 105Ah AGM marine battery; size matters. Chris makes really good points; let the fridge breathe but also put an insulating cover on it to make life easier for the thing. Fuses are really cheap insurance.

khupp: What type of battery isolator are you planning to feed the marine battery with?
 

vartz04

Adventurer
Ciggie ports are an abortion.

Andersons are the bomb.
Yep and now that they have a 2 port panel mount there’s really no reason to use cig plugs. They even sell adapters.

You’d think with all of the “advancement” in how phone charger plugs are made (usb c and lightning) they would start to modify cars to use something better than the cig plug method that’s been around and been garbage for 40+ years.


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Ciggie ports are an abortion.

Andersons are the bomb.
Yep and now that they have a 2 port panel mount there’s really no reason to use cig plugs. They even sell adapters.

You’d think with all of the “advancement” in how phone charger plugs are made (usb c and lightning) they would start to modify cars to use something better than the cig plug method that’s been around and been garbage for 40+ years.


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Can someone post a link to the Anderson plug? I assume you are referring to cigarette plugs?

I did order 2 arb plugs to help make sure it doesn’t come unplugged.


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john61ct

Adventurer
Those RV plugs can only safely withstand current levels for a maintenance charge, except maybe for a tiny breakaway battery.
 

rickc

Adventurer
khupp: research "dual battery systems", "battery isolators" and of course, "Anderson plugs" on the Internet. There are loads of good resources and lots of pictures to make it simple.

In a nutshell, dual battery systems are composed of the starter or main battery (your vehicle main battery under the hood) and a house battery for your fridge and any other goodies you want to use when your vehicle is not running. The starter battery is designed to always be close to full charge; it does not like to be discharged and it will let you know if you do this. Plates will become sulphonated and the battery will never hold full charge again so don't let it drop charge. The house battery is a deep cycle battery that is designed to be run down and recharged many times; it's not good to go too far, maybe down to about 20% of the full charge or around 10.8V. Full charge is around 13.5V or a little higher. Size matters so if you have lots of goodies go with a big amp-hour battery; 105Ah is good for most 130Ah for heavy duty. The fact that you are asking about isolators concerns me; is your house battery a deep cycle one?

An isolator can be really expensive or really simple but its purpose is to make sure the main battery is charged preferentially by the alternator and once it is charged, it will then charge the house battery when the vehicle is running. It also prevents the main battery from being discharged through to the house battery when the vehicle is shut down and you are using your goodies. Isolators are usually placed close to the main battery.

If you want the option to use your house battery as an alternative vehicle starter, there are isolators with bypass switches that allow you to directly connect the two batteries just for starting. If you choose to do this, you must use thicker gauge wiring between the main and house batteries and ensure that there are adequate fuses on the live, +ve cables to prevent damage to batteries and cables. You also need to choose an appropriate deep cycle battery.

As for Anderson Plugs, they make attaching and removing things easier and are a much better option than your RV plus as stated by others. If you go the dual battery route with starter option for the house battery, I would recommend directly attaching the live and ground wires from the main to the starter battery via a fuse or a circuit breaker on the +ve. The size of the wiring depends on the length of the wire and the current running through it so current will depend on your vehicle. There are tables on line to help; for example a 200A draw for start and a 9.5' cable length would require a 1AWG wire.

If you only intend to use the house battery for goodies, calculate the maximum draw in amps, measure the length of cable and use a table to calculate the wire size.

I hope this helps. There are many examples of really good systems on this forum and the Internet.
 

toyick

I build Boat Anchors
Blueseas 7622 is a great option for an isolator.. also Delcity.com has an amazing selection of any thing wiring that you need.


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I just want to post and thank everyone for their advice and let everyone know how it went.

I bought a 24 marine battery at Sam’s and ran 8 awg wire from my Jeep battery (30 amp fuse) to the 7 pin connector. The 7 pin on the trailer trickle charges the marine battery. I tried to test the amperage prior to leaving, but my chepo multimeter only can test up to 10 amps DC. Anyway, I fried it testing, so I guess I get at least 10.

I drove down down in 85 degree weather and my fridge was at 32 F when I arrived 9 hours later. I forgot to test the battery before plugging into shore power.

We drove back yesterday 10 hours (stopped for a one hour lunch with vehicle off). 90 degree heat. Fridge was again at 34 and battery was fully charged. I unplugged my tow vehicle and the fridge is still at 34 degrees 14 hours later.

If I was to do this over again I would run 10 gauge wire. I believe 8 is overkill.

If I was going somewhere off the grid I would definitely consider Anderson connectors because everyone says they are rock solid, battery isolator and solar. For my purposes I am fairly confident that even if there was an issue with the 7 pin terminals not working/ no trickle charge.


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toyick

I build Boat Anchors
Well, i think you are right on target for this.... 10 gauge will net you the ability to get about 30-40 amps to your battery safely.

Your fridge on full tilt should be around 6 amps....

Keep in mind overkill is good. I think you did right with your 8 gauge. I would personally run that through an Anderson, but i think you are on the right track.
 
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