Hi,

I always use the "B" mode whenever possible, like when cruising to a stop light, getting off a freeway ramp etc. with the notion that this technique produces more charge to the battery. Is this true?

I know that the battery charges whenever I let go of the accelerator and cruise (either in "B" or "D"). But is it always better to use "B" everytime possible? If let us say I need to stop within 500 feet: is better to let go of the accelerator at 500 feet, is using "B" mode all the way to the stop point OR letting go of the accelerator at 500 feet, stay in "D" and use the brake close to the stop point? Or is the advantage only to the wear on the brake pads? I sometime feel that i put more wear on the engine when I decelerate in "B" mode at 60mph but wanting the regenerative effect of the "B" mode. If the only advantage is less wear on the brake pads, then I might not be too trigger-happy with the "B" mode.

 

the 'B' mode generates less of a charge. It is meant for engine Braking. It will run the ICE to provide deceleration.

 

I read years ago that when in the B mode ,if it needs extra braking it automatically starts using the engine. If more braking is needed it uses the metallic brakes. That's why I stopped using the B mode to slow down, unless it's a rather steep grade and I'm going slow.

I find it best to use the brake pedal. The harder you press the more generator power is provides up to a point. Then the metallic brakes are used. Listen to the whine as you slow down. That way you can tell when it's near at max at generating power for the traction battery.

 

These cars have small, undersized mechanical brakes. If used to excess, they will overheat and loose effectiveness. Cars have crashed due to brake failure after overheating their brakes. Overheated brakes is a common problem in race cars on tracks that have a lot of turns, but should rarely happen in street cars. One place where it does happen is, going down mountains.

The purpose of "B" is to tell the car to use the "engine braking". When going down a mountain without engine braking, the battery gets full and then the car starts using the mechanical brakes. If you use the mechanical brakes all the way down, they will overheat and loose effectiveness. The "engine braking" uses the engine to absorb some of the energy, to avoid overheating the brakes.

Do not use "B" mode for normal driving. "B" mode is only for going down mountains. It doesn't charge the batteries. Use the brake pedal normally for all normal driving, except for going down mountains. Applying the brake pedal gently, so as to avoid using the mechanical brakes, allows the car to put most of the energy into the battery, from where it can be reused. Of course, when the battery is full, no more energy will fit in the battery, and the car will use the mechanical brakes anyway.

And, of course, when you really need to stop to avoid hitting something, push the brake pedal as hard as you want. The ABS system in this car is really good. It surprised me the first time.

 

As a pragmatist...how much do you think you'll 'save' using one form of braking over another?
Assuming the B increases your charge by X%, what will be the net result, an extra 1 MPG?
Over the course of a year, that might be a saving $5 or $10, if that?
That's one less Starbucks Latte a year
Just drive as you feel comfortable and enjoy the road

 

As a pragmatist, using B DECREASES the amount of charge regeneration as compared to the same amount of slowing done with the brake pedal.

-- Alan

 

To be clear, I meant that I was asking...as a pragmatist (I hope I didn't confuse the issue, nor imply otherwise)

 

In my own experimenting, I have noticed:

1) When starting at high speed and falling below 42mph, the ICE stays engaged, and only disengages when you move from B back into D.
2) When already going below 42mph on electric-only, engaging B mode automatically kicks the ICE into gear.
3) When not moving at all, moving from D into B does not engage the ICE. I do not know what happens when you accelerate in this mode, as I thought it was probably a bad idea to see.

So I'm pretty sure that B mode engages the ICE engine to provide some additional slowing of the drivetrain, thus it does not make sense that it would generate more charge. The opposite is likely true; it most likely generates less charge.

 

Mithrandir's explanation matches the function that happens in my Nissan Altima Hybrid also.
For #3 I've accidentally had my car in B and accelerated fine, just when I let off the gas, it started slowing down immediately which let me know that I had done something different. It also made the engine rev higher then it would normally, which didn't matter as I was <30 mph.

 

Altima Hybrid has Toyota HSD in it.

I found one psychological disadvantage to using B mode. I use it when I go downhill to decelerate and to take sharp curves, like clover type off ramps, at higher speed and less brakes use. anyhow, my downhill use terminates in usually red light. call me stupid, but it's a long downhill, and I caught myself several times that I relied on B deceleration so much, that I almost forgot to use brakes to stop at the red light. Sort of allowed car to stop it for me.

Also, Toyota states that continuous use of B mode will "damage certain bearings".