Regenerative Braking Questions

1. Are there any disadvantages of the B mode (as opposed to D)?

2. At what point are the friction brakes employed? Only for real fast stops? I want to maximize power regeneration.

Thanks.

For #2: http://www.mynissanleaf.com/viewtopic.php?t=12290

It's a very common mistake to try to maximize regeneration while ignoring coasting. In fact, coasting is much more efficient than Regen, because using Regen wastes at least half of the energy available, as heat. Coasting doesn't generate any extra heat at all, so while it might be misleading to call it 100% efficient, it's still the most efficient way to extend range in situations where braking is unnecessary or optional. Braking mode works best in urban driving, where frequent braking is needed. Coasting works better in most other situations.

LeftieBiker said:

It's a very common mistake to try to maximize regeneration while ignoring coasting. In fact, coasting is much more efficient than Regen, because using Regen wastes at least half of the energy available, as heat. Coasting doesn't generate any extra heat at all, so while it might be misleading to call it 100% efficient, it's still the most efficient way to extend range in situations where braking is unnecessary or optional. Braking mode works best in urban driving, where frequent braking is needed. Coasting works better in most other situations.

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Very interesting. 80% of our driving will be on highways.

So, if I'm driving on a freeway with hills, and I set the cruise control to 55 MPH, D mode would be more efficient.

I am a three week newbie, so that'll reflect in my answer.

I find myself switching back and forth between D and B while driving depending on the situations.

D mode when I am on an open road or highway. Momentum is key to using less energy. If you are in B mode on an open road, you use more energy gaining speed you lost in regen in B mode.

B mode if I am in stop and go traffic or on a road that requires slowing down (corners, obstructions, etc..) Just be aware that in B mode, you are slowing down without brake lights. Watch that car behind you.

On my 2016 SL, there is a screen in the center I use all the time to watch the power used and gained in KW. You can tell from this screen at what point the brakes stop using regen and actual brakes. You can feel the pedal and see the gauge going to 30KW regen. Again this is not on the regular instrument panel cluster, but the center screen.

I don't use cruise control, because cruise doesn't see the large hill ahead or the big slow down ahead.. Where a human can see the large hill and react accordingly

I drive in B because it's fun. I like carving corners and off ramps without touching the brakes.

EVforRobert said:

I drive in B because it's fun. I like carving corners and off ramps without touching the brakes.

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Yes agreed, I failed to mention that in my post!!

Very interesting. 80% of our driving will be on highways.

So, if I'm driving on a freeway with hills, and I set the cruise control to 55 MPH, D mode would be more efficient.

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Yes. And a D mode with zero regen would be most efficient, were they to offer it. My Vectrix electric motorcycle has a great regen control: you turn the throttle backwards to add as much regen as you want, or none by leaving it alone. It works great.

PianoAl said:

LeftieBiker said:

It's a very common mistake to try to maximize regeneration while ignoring coasting. In fact, coasting is much more efficient than Regen, because using Regen wastes at least half of the energy available, as heat. Coasting doesn't generate any extra heat at all, so while it might be misleading to call it 100% efficient, it's still the most efficient way to extend range in situations where braking is unnecessary or optional. Braking mode works best in urban driving, where frequent braking is needed. Coasting works better in most other situations.

Click to expand...

Very interesting. 80% of our driving will be on highways.

So, if I'm driving on a freeway with hills, and I set the cruise control to 55 MPH, D mode would be more efficient.

Click to expand...

It depends on the hills. D mode will only be more efficient if the hills are steep enough that your speed increases to over 55 in D mode due to the steepness of the hill vs. the weaker regen. So it depends on the hills and also how much overspeed you are comfortable with. And, you have more options than just setting D or B and engaging cruise control. I tend to use B mode and then if I want to maximize efficiency in hills with cruise enabled, I can feather the accelerator pedal as necessary to either null out the regen, or to obtain a regen load that maintains a speed that is acceptable to me. In effect, you have infinitely variable regen available this way. To me this makes B mode the more versatile and tractable choice.