Isolator Recommendation to Prevent a Trailer Battery from Draining a Vehicle Battery

Updated 09/19/2012 | Published 09/17/2012

Products Featured in This Question

Universal Installation Kit for Trailer Brake Controller - 7-Way RV and 4-Way Flat - 10 Gauge Wires

(3480)

$118.67

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

(14)

$35.41

Question:

if this kit is used to connect a brake controller to a towed trailer that has its own 12v battery, then if the tow vehicle is running, will the trailers battery be charged through the 7 pin connector? and conversely, if the tow vehicle is not running, will the trailer put a drain on the tow vehicles battery through the 7 pin connector? thank you.

asked by: David

Expert Reply:

If you have a 7-way installed on your vehicle and trailer and the 12-volt power circuit goes to a battery installed on the trailer it will lightly charge the battery when the connectors are connected. You should note that it will not charge a dead battery back to life, but it will more or less maintain a good charge on a battery if it is in good shape already.

If you are worried about your trailer draining your vehicle battery if the connectors are left together you have two options. First, you could disconnect your trailer connectors every time you park your vehicle. The other option is you install a Battery Isolation Solenoid # PK5231201. This product is designed so that unless your vehicle is turned on the 12-volt circuit of your vehicle is disconnected.

How it works is you install it inline of your 12-volt power circuit on your tow vehicle and then run a power source to the middle terminal that only sees power when the key is on. When there is power on the third terminal it completes the circuit and allows power to go to the 7-way, but when you turn the key off the 7-way will no longer have power.

expert reply by: Jameson C