Charging The Toad

Wiz,

Ford, GM and FCA all have wobble problems when towing a EPS (Electronic Power Steering) vehicle. EPS does not have adequate damping unlike hydraulic. Hence the fix to leave EPS on when towing.

And that power comes from the battery when towing. And I suspect the power consumption is significant when towing but that is why I asked if there were any actual power measurements.

The OP stated his battery would be dead at the end of a day unless the car was started during the day. Lots of loads including EPS are involved.

I agree that a DC-DC converter might be a solution. I'd want to know the loads and wiring before deciding on a solution.

There is some indication that the EPS/wobble problem is starting to be addressed in some 2019 vehicles.

CA Traveler wrote:
A potentially huge draw would be EPS which apparently the OP has since he mentioned wobble. Has anyone measured the amps used when towing especially with EPS running?.

Why would electric power steering be operating ?

EPS can draw a large current, but that would be is slow "parking" type maneuvers. The reason why manufacturers a switching to EPS over hydraulic power steering is that they do not take as much power from the engine.

A hydraulic PS pump is running all of the time at maximum volume just pumping the fluid around in a circle. It needs to operate this way so that it is always ready to assist you. EPS standby current is tiny and the battery is there to handle the short, high current demands.

Use a DC-DC battery charger between the tow vehicle and the towed vehilce.

Any charging device that rubs a tire would not be my favorite. Connected to the drive shaft maybe.

Perhaps the simplest is a wind turbine mounted on the tow bar?

BTW There was a post indicating that GM stated in a phone call that the 2019 Equinox does not have a wobble problem when towed. No details were available.

It would be interesting to know what amp draw/wiring size is required for various newer cars/trucks that are towed. Considering navigation equipment etc that remains on, etc.

A potentially huge draw would be EPS which apparently the OP has since he mentioned wobble. Has anyone measured the amps used when towing especially with EPS running?

My Jeep has hydraulic steering with an electric motor running the pump. It appears to have 8 gauge wire to the motor which implies a lot of power is needed. I'd bet a donut the EPS also requires a lot of power. Just wondering how much is required for towing?

I'm beginning to suspect that the common 12 gauge charge lines just aren't enough for many newer cars.

In my experience aux brakes take very little power due to infrequent usage. But always on navigation, EPS, etc could have increased power usage.

STBRetired wrote:
Have you verified that there is 12V present at your 7 pin connector? Mine originally did not. There was a wire connected to pin 4 but no voltage present. Traced the wire back and it went to an auxiliary fuse panel but was not connected. My Brake Buddy would kill the battery in about 6 hours. Connected the wire and installed a 20A fuse. No more problems.

I checked that right after the shop finished the install. I'll check it again. I would suspect the RVi brake, but it's been mostly highway driving.

red31 wrote:
bicycle dyno https://www.amazon.com/Bike-Bicycle-Dynamo-Generator-12V/dp/B000OBWMGK

Thanx Red. That's what I remember. My guess is 6 watts isn't enough.

Just fix whatever is wrong with your charge line from the motor home. It's the simplest solution. On the big airplanes we call what you describe a RAT. It's a Ram Air Turbine that drives a hydraulic pump.

bicycle dyno https://www.amazon.com/Bike-Bicycle-Dynamo-Generator-12V/dp/B000OBWMGK