Why Must the Negative Battery Cable Be Disconnected on a Jeep Wrangler to Flat Tow

Updated 11/08/2013 | Published 11/06/2013

Products Featured in This Question

Roadmaster Battery Disconnect for Towed Vehicle w/ Flat Tow Brake System - Gas Only

(385)

$223.05

Deka Lead Quick-Disconnect Battery Terminal - Universal Polarity

(34)

$29.82

Roadmaster Battery Charge Line Kit for Towed Vehicles

(1235)

$42.90

12 Volt Outlet Kit, 20 amps

(342)

$38.36

Question:

I was reading the manual on my 2014 Jeep Wrangler Sahara and it says Disconnect the negative battery cable, and secure it away from the negative battery post. Why is this? I will be using a portable brake controller like the Patriot so I need power for the portable brake controller. What is your advise on setting the Jeep up to charge the battery while towing and providing a quick disconnect to the battery to comply with the manual. Thanks for your help and advise.

asked by: Mike W

Helpful Expert Reply:

Jeep recommends disconnecting the negative battery cable when flat towing to prevent the battery from draining. When you flat tow your Wrangler, the ignition must be left in the ACC position. This would leave certain electronic components on that could drain the battery.

For your situation, I recommend installing the Roadmaster Automatic Battery Disconnect, # RM-766, on the positive battery cable so you don't lose your ground to the chassis. I know the owners manual says negative cable, but this is the tested and recommended method from Roadmaster. To run a battery charge line to your Jeep's battery, I recommend using the Battery Charge Line Kit, # RM-156-25.

A more economical option would be the Battery Terminal Quick-Disconnect, # DW05312. This is permanently installed on the battery cable and terminal and allows you to easily disconnect the battery cable each time you want to tow. You can still use the Battery Charge Line Kit with this disconnect.

To provide power to your supplemental braking system, I recommend using the 12 Volt Outlet Kit, # RM-9332. This kit attaches directly to the battery terminals and provides an accessory outlet to power your braking system.

I have attached a few demonstration videos for you to check out.