How to Prevent Trailer Battery from Draining Tow Vehicle Battery

Published 05/27/2022

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Starter Solenoid - SPST - 12 Volt - 100 Amp - Continuous Duty - Grounded

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Question:

I want to add a battery to my trailer so the loading and interior lights will work when not connected to my truck. Ive read about an interrupt switch or solenoid to keep the truck battery from draining in certain circumstances. Just not sure what all I need to do to make this work. Ive attached pics of what i currently have in the trailer if that helps.

asked by: Joel

Expert Reply:

To prevent your truck battery from draining from an auxiliary trailer battery like you plan to install when the vehicle is off you'd need to install an isolation solenoid on the 12 volt accessory circuit like with the part # PK5231201. This will open the circuit when the vehicle is off so that the battery couldn't drain the main truck battery. Another option would be to always disconnect the trailer wiring when parked.

A deep cycle battery like the part # BRW34FR would work great for your interior and exterior lights then for a battery box the # 329-HM300BKS would work great. I'd recommend 10 gauge wire to run from the 12 volt accessory circuit of the 7-way to charge the battery.

expert reply by: Jameson C