What Prevents RV Battery From Draining Tow Vehicle Battery When Vehicle Isnt Running

Updated 09/10/2020 | Published 04/22/2019

Question:

What, if anything will limit the current flow back to a severely discharged RV battery? I see you can get a 30 or 40 amp circuit breaker but that should probably cut out if it detects such a heavy draw to the dead battery. Is it like a slow trip that will give a few seconds before tripping out? I know the current flow to that battery should diminish once it comes back up some and slow to a lower current demand, but will it still allow that battery to charge or do you need to charge the battery manually so the current draw is lower than the breaker? I have a 2017 Honda Ridgeline that has the factory tow package wiring harness that current limits to about 2 amps and is just not enough to keep the camper battery up while driving with the fridge running. My current fridge draws about 18 amps in DC mode and a 30 amp breaker should be just fine, but if the battery gets too low I am afraid the charge current might be too high and trip out the breaker. Thanks in advance for any help.

asked by: Scott B

Expert Reply:

When you use an isolator like the part # PK5231201 what activates the solenoid to allow current to pass through is is the center pin of the solenoid. You run a keyed power source to this which allows the circuit only to be active and charging your trailer battery when you have the vehicle on.

Refrigerators draw quite a bit of amperage so it would be nearly impossible to charge your battery enough while travelling through the 7-way while the fridge is also running.

expert reply by: Jameson C

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Andrew M.

9/7/2020

2018 ram pulling a 2020 Salem 273qbxl . need to isolate truck battery and still be able to charge trailer battery. What kit and installation instructions

Jon G.

9/10/2020

It sounds like you're looking for the isolation solenoid that Jameson mentions above. If you're looking for something that is built for better charging then you'll want something like the BCDC # 331-BCDC1225D and the Fuse Kit # 331-FK40. The BCDC has a built-in isolator.