I just ordered a Raptor, so while researching dual battery options I found this thread. I’ve been running an ARB fridge for the past three years in a few different vehicles, a 2011 VW Touareg TDI, 2017 Subaru Outback, and currently a 2015 VW Passat TDI. I travel to Phoenix or farther 35+ weeks per year and use an ARB fridge to keep my food for the week. If the fridge fails my food spoils, unacceptable. Here are my experiences in Phoenix summers:
2011 Touareg with ARB 50 quart in transit bag - ran off the stock Group 49 battery and stock wiring in the back of the SUV. If not driven daily the fridge hit the cutoff the morning of day 2, or sometimes late afternoon of day 1 if 110+ degrees and parked in the sun.
2017 Subaru Outback with same 50 quart - the stock battery in the subi is shit, only 350 CCA, fridge was dead before 5pm on a 90 degree day. Was running on the stock wiring in the back. Upgraded to an Optima yellow top 24/78, helped some, but the fridge died quickly on days over 100 degrees.
2015 VW Passat with 37 quart in transit bag - I installed a group 31 yellow top with a blue sea systems automatic charging relay in the trunk with a run of 8 gauge from the OEM battery to it. The fridge will run for 2-3 days without running the car in any temperature, even when the trunk is pushing 150 degrees on a 110+ degree day. On spring days under 90 degrees the fridge will run for 5+ days. The Optima battery died in 15 months (like they usually do) so I swapped in a better AGM battery and it’s been fine for another year. This setup is awesome.
I’ll need to install the 37 quart in the Raptor. I ordered a Scab, so there isn’t much space in the back. I’m going to investigate removing the entire rear seat behind the driver’s seat to build a platform for the fridge (maybe with a battery under it), if that can’t work I’ll have it in the bed under whatever tonneau cover I buy. If there is a different fridge that fits in the cab better I have no issue buying it, so maybe and Engle or something. I never have more than 3 people in my vehicle, so I’d rather have the fridge inside.
I saw a Raptor in the body shop a while back that had an aftermarket tube prerunner style bumper, there was a battery mount behind the skid plate where a winch would usually go. I thought it was terrible for weight distribution. I would much rather do a box off the frame somewhere more central on the truck.
Here is the charge relay I use. It’s voltage controlled and has worked great in the Passat for the past 2.5 years in the AZ heat.
https://www.amazon.com/gp/product/B000OTIPDQ/?tag=fordraptorforum-20
Here is a picture of the Passat setup with the yellow top.