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Should I Disconnect My Ford Edge Battery Before Flat Towing and Can I Still Use A Braking System


so then Heather, this might also explain why my battery went dead on an older Honda car that I towed for about 7 hours. Battery disconnect switches werent even mentioned for that 2011 Honda Accord back then. so technically I dont really need to disconnect and the car won t be damaged, other than the battery might get drained? Does the switch you mention have anything to do with a supplemental braking setup?


Helpful Expert Reply:

It does sound like the older Honda's battery was drained because the ignition was in neutral and the vehicle's features or accessories were drawing power while being flat towed. Vehicle manufacturers have since realized this and require the battery to be disconnected in some vehicles. We do recommend that you disconnect the battery like the owner's manual says to prevent the battery from draining. Since vehicle's have more electronic features and more sophisticated computer systems then in the past it is possible leaving the battery connected could cause issues while flat towing. From my research there have been issues with electric power steering system in the Edge if the vehicle battery is left connected while being flat towed although I have not confirmed that with Ford at this time.

The disconnect switch itself doesn't have much to do with the supplemental braking system but supplemental braking systems require 12V from the vehicle's battery to operate. The Roadmaster Automatic Battery Disconnect with Switch # RM-766 allows you to disconnect the battery with the switch without pulling the cable each time. The switch just makes it easier to disconnect the battery from the vehicle. I have attached a video of this part on the Ford Edge for your reference.

To charge the vehicle battery (because it's disconnected) to power the supplemental braking system, I recommend to use a charge line from the motor home to the vehicle with Roadmaster Battery Charge Line Kit for Towed Vehicles part # RM-156-25. This will allow you to keep the vehicle battery charged using power from the motor home even though the vehicle's battery is disconnected from the vehicle itself. Since the battery is being charged from the motor home you can power the supplemental braking system in the vehicle. If no charge line is present in your RV, you will also need to add the Motor Home Charge Line Kit # RM-156-75. I have attached an installation video of this on a Ford Edge for your reference.

Now that your vehicle battery is being charged from the motor home, you can use a supplemental braking system like Stay-IN-Play DUO Supplemental Braking System # SM99251 which is the best and most permanent option if the motor home has hydraulic brakes. The main unit of the Stay-IN-Play is wired and installed underneath the hood while the small actuating cylinder mounts on the arm of the Ford Edge's brake pedal. The cylinder depresses the brake pedal upon receiving air from the main unit which is activated by the motor home's braking. If you go with this braking system there will not be a requirement for any other parts regarding the braking system besides the disconnect switch and the charge line that I mentioned earlier.

Some braking systems like the Roadmaster InvisiBrake Supplemental Braking System # RM-8700 require the use of a stop light switch part # RM-751475 so that the supplemental braking system knows when the motor home is braking. Also some braking systems like the Blue Ox Patriot part # BLU37TR plug into a 12V outlet and require a 12 Volt outlet kit part # RM-9332 to be used in vehicle's that require battery disconnect during flat tow like the Ford Edge. Some braking systems require both the stop light switch and the 12V accessory outlet, it really just depends on how they install.

helpful expert reply by:
Heather A

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