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Charging Trailer Mounted Battery through 7-Way Connector on 2011 Toyota 4Runner  


I have read some of the posts and responses, but I am unclear if I will need a separate charger to charge a battery installed in an enclosed trailer to run lighting and the like in the enclosed trailer. I have a 2011 Toyota 4Runner with 7-pin installed tow package. I want to make sure I have a way to keep the battery charged in the trailer without draining the 4Runner battery. I understand the trailer electrics, but unsure of correct wiring for 7-pin to battery to ensure proper charging.


Expert Reply:

A small breakaway battery such as # HM20008 can be charged from the 12 volt circuit from the 7-Way connector. You could connect the 12 volt circuit directly to the positive battery terminal.

But a larger battery, such as a car battery mounted on the trailer, can only receive a maintenance charge for the 12 volt circuit. This is because the wiring for the trailer connectors is too small and the vehicle alternator is not strong enough to push back the amperage required to charge up a trailer mounted battery.

If the 12 volt circuit on the vehicle is hot all the time, even with the vehicle off, then installing a battery isolation solenoid, # PK5231201, would shut off that circuit when the vehicle is turned off.

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