wehey
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Regen/Brakes in D and B mode

Fri Oct 13, 2017 5:12 am

When you drive in B mode and lift off the accelerator you get up to 4 dots of regen depending on speed.
If you use D mode then you usually get 2 dots until you apply some brake.
When you do add a little brake, enough to get 4 dots, are you getting pure regen as in B mode or are the brake pads applied and doing some of the braking ??
I monitored both modes using the Energy screen and you get the same amount of power back at a given amount of dots regardless of which mode you are in.
I just wanted to understand if brakes are also applied when using D mode??

jjeff
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Re: Regen/Brakes in D and B mode

Fri Oct 13, 2017 5:30 am

Good question, it's my understanding that if you gradually press the break pedal regen is tried first, if regen maxes out and you keep pressing harder, the friction breaks will kick in. So in your case, if you only pushed on the break pedal hard enough for the 4 dots of regen to come on and no harder, it should be just regen.
Because of this and I'm not always sure if I'm pressing too hard on the pedal, I like to use B(or ECO on my '13S) and only use the break pedal if regen isn't enough to slow the car down.
Our Prius is the same, pushing the pedal lightly first kicks in regen, then a harder push will begin to apply the friction breaks. Personally on our Prius I don't use B mode as I feel it stops the car too much and doesn't allow coasting, I just lightly feather the break pedal if I only need to stop slowly(or sometimes I engage the B mode to stop or for long hills). IMO my Leaf has is just about perfect regen in ECO(no B mode on S model Leafs, at least mine) with just enough regen to slow the car but not too much as to impede coasting. Probably my favorite would be steering wheel paddles like on the Bolt, maybe some day.
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wehey
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Re: Regen/Brakes in D and B mode

Fri Oct 13, 2017 5:44 am

Thanks for the reply jjeff.
I haven't been using B mode for quite a while now.
I decide to drive in B mode today and the question appeared in my head.
Just trying to understand the best way to recapture some energy when coming to a stop.
So B mode really doesn't have an advantage over a carefully used right foot. It's just an easier driving experience using B around town I guess

jjeff
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Re: Regen/Brakes in D and B mode

Fri Oct 13, 2017 6:19 am

wehey wrote:So B mode really doesn't have an advantage over a carefully used right foot. It's just an easier driving experience using B around town I guess

Yes, thats how I understand it, more of a one footed driving experience, even if at the expense of some efficiency(not being able to coast as well).
2012 SL purchased used 2/'16
2013 S w/QC purchased new
Juicebox Premium 60a L1/L2 EVSE, Ebusbar 16a L1/L2 EVSE
'12 EVSEupgrade'd 20a L1/L2 EVSE, '13 EVSEupgrade'd adjustable 6-20a L2, 6-13a L1 EVSE
Zencar 13, 20, 30a L1/L2 portable EVSE
GE Durastation 30a

estomax
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Location: Seattle

Re: Regen/Brakes in D and B mode

Fri Oct 13, 2017 8:33 am

the brake master cylinder rod is connected directly to the brake pedal. i would expect as soon as you press on it, it will start compressing hydraulic fluid. Very little at first while the regen is taken into account but i would bet that you are doing a small amount of real braking while regening that you wouldnt be doing in B mode.

there certainly isn't any valve to block real brakes at the beginning of the brake pedal stroke, that would be a safety hazard.

Marko
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hackdroot
Posts: 67
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Delivery Date: 15 Apr 2017
Location: East Bay Area, CA

Re: Regen/Brakes in D and B mode

Fri Oct 13, 2017 9:39 am

I drive using B like a manual tranny downshifting. Shifting into B (or Eco, or B/Eco) to slow down and only using brakes when I need additional stopping power. I see no reason to waste that potential that could be recovered (albeit minimal at times). Plus, I'm extending the life of my brakes at the same time. After a while it becomes second nature. I also coast when I can. I figure, if I can get where I'm going using the fewest positive dots, for the shortest duration possible, I'm being as efficient as I can be.

That's not to say I don't have fun with the car when I want/need to. ;)
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NeilBlanchard
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Leaf Number: 306278

Re: Regen/Brakes in D and B mode

Fri Oct 13, 2017 9:43 am

If you get the dots, you are getting regen.

johnlocke
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Re: Regen/Brakes in D and B mode

Sat Oct 14, 2017 10:52 pm

Using B mode, the regen kicks in at a higher level compared to D mode. It is speed dependent as well. You can get 4 bubbles of regen in B mode at 65-70 just by letting off the gas pedal. At 40 mph in B mode only 2-3 bubbles. In D mode at 60 mph you'ld only get 2 bubbles unless you touch the brakes. In either mode regen is limited until the battery drops below 95% and isn't fully active until the battery is below 90% It's a PITA because I drop 1500 feet during the first 12 miles of my commute and I can't recover hardly any of it if I start out with a full charge. If I start with a full charge i'll use 5-7% during those first 12 miles. If I start out at 85% or less, I'll only lose 3% for those same 12 miles. Going back up the hill costs me 20-25% of the battery charge.

Oh yeah, just to make it more complicated, a warm battery will accept more regen than a cold battery at the same state of charge.
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arnis
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Re: Regen/Brakes in D and B mode

Mon Oct 16, 2017 3:23 am

Brake pedal will max out regen in any mode, but unfortunately blending is not perfect.
Most noticeable is when you slowly touch brake pedal. Most of additional braking
action comes from friction brakes. Regen kicks in later. Or it will kick faster but only when
brake pedal is pushed lightly but rapidly.
Best gauge to see how much frictional brake is used is to look at the "TREE BARS"
They disappear as soon as friction is used. And reappear when friction brakes are disengaged
and additional regen engaged (sometimes happens just by waiting and not changing pedal action).
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