Adding an External Battery to a 2018 Interstate Trailer with Trailer Breakaway Kit

Updated 09/19/2017 | Published 09/18/2017

Products Featured in This Question

CTEK MULTI US 7002 12-Volt Universal Battery Charger w/ Pulse Maintenance and Backup Power

(98)

$199.99

10 Gauge Wire - Blue Primary - Per Foot

(107)

$1.65

Redarc In-Vehicle BCDC Battery Charger - Dual Input - DC to DC - 12V/24V - 40 Amp

(87)

$620.00

Roadmaster Single Park Light Diode

(128)

$18.90

Solar Power Kit for TorkLift PowerArmor Battery Box - 10 Watt Panel

(4)

$233.23

Question:

I am adding an external battery for my interior lights as they do not work off the trailer brake battery when unplugged which wire do I use for my power in the trailer and before or after the trailer brake battery. I was told to watch out for a charge back problem? Thanks

asked by: Keith B

Helpful Expert Reply:

A trailer breakaway battery is a smaller battery that you definitely do not want to use to power the lights in your trailer with. As convenient as that would be, it could drain the battery enough that the breakaway battery would not activate your trailer brakes long enough to safely bring your trailer to a stop. Adding an external battery, as you are wanting to do, is the way that you want to go.

What you will want to do is use 10 Gauge Wire # 10-1-1 and run it to the pin in the 11 o'clock position (see attached picture) on your trailer side connector. This will enable you to receive a maintenance charge to your external battery while the vehicle is connected to the trailer. You will want to use the Roadmaster Single Park Light Diode # RM-690 to keep from that charge back problem happening.

Since this solution will only provide a charge that maintains the battery level you will want to use either the CTEK MULTI US 7002 # CTEK56353 to charge the battery while the trailer is parked, or the Redarc BCDC Battery Charger # 331-BCDC1240D and a Solar Panel # TLA7713 to trickle charge it from both the tow vehicle and solar panel while you are out on the road. I have attached a picture displaying the setup that includes the solar panel.