I recently started after a cold soak.
I immediately needed to back 1/4 mile, in reverse, slightly uphill to get out of a narrow driveway.

During this time, all "movement" of the car was from battery power.
Without watching the SG ( my eyes were on the rear of course, my SOC dropped to the typical 33% during a cold start.

Then, what got my attention........
I was in reverse, with foot on the brake, pretty much stopped, if not totally stationary at the time... VaaaROOOOOOM!!!! Engine speed started to race to 2200 RPM with foot on the brake. Battery assist ceased at exactly 33% SOC. To finish backing the last little bit, the engine raced even higher with the slightest touch of the go pedal. To confirm my hunch... I got saftly on level ground, and just paused... keeping the car in R position, but not moving.
And neither did the SOC. It stayed parked at 33% or 32.9%. Not climbing at all until I put the car in drive. Then charging started in earnest. Then I moved the position to R again, and charging ceased again.

Not only did assist cease, but, it seemed, so did the engine idle.

Not a biggie... just an observation I hadn't heard discussed before.

-John

 

Who, in writing the firmware specifications, would have foreseen a need to drive 1/4 mile in reverse...??

 

I have to think that's been considered....our driveway , in our previous house, was narrow and almost a half-mile long. That's why we built a turn-around right after we bought it. Glad we no longer have it though...especially in the winter.

 

Could be one reason for the low towing rating?

 

Manufacturer's tow ratings are ignored here!

 

I had a similar observation while packing my driveway (using the MMH as "heavy equipment" ). At first, I was going forward down the hill for better steering and reversing back up. This obviously depleated the battery quickly going reverse uphill so I turned around and started going down the hill in reverse, up in "D".

Even though the battery was down in the 30s, it only climbed back up when idling and (a little) on the climb up the driveway in "D". After I was done, I let it idle for a bit until the SoC got back up in the mid 40s.

 

Since the reverse is pure electric, I don't think there is any way to engage the generator to produce electricity - the generator has to be engaged with the engine. I suppose they could have figured out a way to do it, but it is far simpler to just disconnect everything when in reverse.

 

The engine can spin the generator, and the generator can send power to the traction motor while in reverse. So why not send it to the battery if approproate? Flooring the pedal to go up a hill in reverse will send greater than 100 amps to the traction motor, and I thought the battery was "fused" at 100 amps so normally never comes close to that.

 

Hey, I never said it wasn't possible, just that Ford did not choose to do it. I wish I was privy to their thinking in this instance.

Perhaps it has to do with not allowing the electric motors to over heat (they could only be used while there was sufficient SOC)?

 

Exactly.

HSD style vehicles lack a true reverse gear and back up on electric only. That there is no charging in reverse does not come as much of a surprise. In fact it would be a surprise if there was charging in reverse.