Hybrid towing

EB Expedition wrote:
We just upgraded to a new Class A motorhome and traded our Expedition in for the 2013 Ford CMax Hybrid. We are using Blue Ox tow bar and RViBrake2 for the CMax. Connect the CMax to the tow bar.

The CMax has the push button start. To setup the car for towing: do not press the brake pedal when pushing the start button (this will put the car in Acc. mode). Ensure that the parking brake is set, then press the brake pedal and shift into Neutral and release the parking brake. Follow directions for the brake controller. After completion verify that the brake lights on the CMax are not lit before traveling. I failed to do this and fried two tires (not cheap to replace) with the brakes being applied. Also note that the CMax will go into standby mode after approximately 1 hour, turning off the 12V outlet in the center console. I had to run a dedicated 12v adapter from the battery to use with the RViBrake2. We make it a habit not to drive more that 4-5 hours each day, and we haven't had our new RV for long, so we haven't had an issue with a dead battery as of yet. If this happens then I may consider putting in a 12v charger or direct 12v from the RV. For safety, as with any tow vehicle (toad or TT)always check everything periodically while on the road.

Me thinks, although you've not had a problem yet, you're going to soon be running a charge line (direct 12V line from MH to your Cmax's battery). Or, wishing you had.

If you have a clip-on ammeter, do this one time: Go through all the motions/procedure you mentioned above for setting it up to flat tow. Tranny in neutral, etc. Then, clip your ammeter on one of the wires going to the battery, see what kind of amp draw you have on the battery. Have someone engage the RVibrake a few times to make it engage the brakes, and watch that ammeter.

YMMV, but I found with our Ford Fusion hybrid, there was a constant 3 amp draw on the battery all the time when it was in 'flat tow' mode (tranny in neutral, ignition in ACC position). Have spoke with other hybrid owners that found the same thing as well (both Cmax and Fusion hybrid owners). And this is before even considering the amperage your RViBrake system uses.

And, remember, power braking assist stays on all the time with these hybrids, so every 2nd or 3rd time your RViBrake engages the brakes, the vehicle's brake boost vacuum motor will come on also and use battery power. And, as alluded to earlier, there is probably other systems that may cycle on and off from time to time when towing these hybrids, that would take even more from the battery.

Our first trip towing the Fusion, I did not have a charge line installed. 'Twas about a 4 hour drive, and that was all it took to run battery almost completely dead - it couldnt even operate the power locks. That was all it took for me. I installed the charge line right after that. We've never had to worry about the Fusion's battery again since then, no matter how many hours we're on the road towing.

Remember also, that starting batteries are not meant for deep cycle use, which is what you're using them for in this case if you don't run a charge line. Using a starting battery this way will shorten its life span significantly. A charge line is much, much cheaper than a new 12V battery. :)