I can readily understand that it' s a good idea to use regenerative braking instead or along with friction braking when the brake pedal is actually depressed.

What I cannot understand is the use of regenerative braking during periods of coasting. How does the hybrid system know of my intent?

Maybe my intent is to extend FE by coasting slowly to a stop at that upcoming stop sign or traffic light. It seems to me that since regenerative braking can NEVER recover enough energy to overcome the fuel savings I might attain by simply coasting it would be better to only use regenerative braking instead of friction braking or along with same.

Or why not a clutch-like control wherein I can "tell" the system my intentions. Regenerative braking unless I activate the "clutch" indicating my intention to coast and thereby increase FE even more.

 

I believe your intent is figured out by how far you press the pedal. In the HCH, if I barely touch the brakes, it's all regenerative braking, if I press harder, it's BOTH. I don't think you can get it to not use regenerative portion.

 

He's talking about regenerative braking during coasting in Low or Drive, not while depressing the brake pedal.

 

Ah... I find it also to be a manner of pedal pressure but in this case the gas pedal. If I let go of the gas pedal quickly, I get the regen to kick off. If I slowly release the gas, I get it to go into neutral. If I barely touch the gas, I can cancel regen without accelerating.

 

It's all just to make the vehicle behave like a "normal" vehicle.... via simulated engine braking.

It's the same thing when you're 'in gear' and let off the brake pedal, the vehicle moves forward while there's really no reason to if you don't press the accelerator pedal.

The engineers did this to make it behave like a conventional automatic transmission, so they could minimize the learning curve and eliminate potential barriers to adoption of these newfangled gizmo cars.

 

You can tell the vehicle of your intent to coast by shifting into N-Nuetral....which I understand prevents all regen unless you hit the brake pedal (actually, even if you do push the brake pedal while in N - no regen is signaled). Kinda like shifting out-of-gear to coast in a manual transmission....

 

No... if you shift to neutral you eliminate regen all together so that is a way around it. Braking is now completly achieved by the brake system.

 

And shifting into L will increase regen. I try to use that in place of brakes if I can.

 

We can use D & L to give the FEH a hint at our intentions since it cannot guess it. If I am in stop and go traffic, I stay in L because it is more agressing with the regen when coasting (essentially coming on when I let go of the gas). When driving in open road where I would want to coast further, I use D as it lets the car coast more.

Cheers,

rcomeau

 

I thought that was the difference between "D" and "L"?

In "D", you coast when you release the gas pedal. In "L", you regen'ed when you released the gas pedal. Basically, "L" uses regen to simulate the back torque of an engine with a regular transmission that is in a low gear.

If you are in "D", and want to regen, you press lightly on the brake pedal.