[Sean Nelson]

I'm interested to find out how well regen performs using the brake pedal in "D" mode vs. using "L" mode with no pedal. We know that the Bolt will do regen with the brake pedal, but is it as much as you can get in "L" mode? So if there are any Bolt EV owners out there who are willing to check their power meter while decelerating both ways then I'm sure we'd all be glad to hear the results. It would also be useful to hear how use of the regen paddle factors in.

Another thing I'm interested in is whether coming to a complete stop in "L" mode uses battery power. At very slow speeds there's little to no regen so I'm thinking the Bolt must apply negative torque to the drive wheels in order to stop completely - and of course that would use battery power. So perhaps some kind owner could check the power meter while decelerating in "L" mode to see if it goes from regen to discharge as the speed drops to 0.

 

[Paulacton84]

there is too much going on in the system for you to quantitatively know what the total regen power was from a given stop. remember also that most drivers use the vast majority of their energy just going at travel speed, the recover through regeneration is nice, especially in a hilly area, but the difference between on type of regen and another is not really much in of your total charge.

 

[Sean Nelson]

there is too much going on in the system for you to quantitatively know what the total regen power was from a given stop.

I'm just talking about looking at the power meter to the right of the speedometer to see what the number of kW going into or out of the battery is. It's not precise, but I'm just looking to see if there's any significant difference between "D" and "L" modes.

 

[Ladogaboy]

I haven't seen any losses coming to a stop in L over D.

In terms of characteristics, the max regen in L is dictated by the battery's SOC. Over ~90% SOC, L and D are almost indistinguishable (both producing about 15 kW of regenerative braking). The regenerative breaking quickly ramps up for L after that (while D remains unchanged).

In anything over 50-60% SOC, max regen (including the Regen on Demand paddle) appears to be 60 kW. Under that SOC, max regen appears to be 70 kW (I haven't experienced anything higher).

 

[Sean Nelson]

I haven't seen any losses coming to a stop in L over D.

Interesting - so you see some amount of regen right down to 0 mph in "L" mode? That would be very impressive.

In terms of characteristics, the max regen in L is dictated by the battery's SOC. Over ~90% SOC, L and D are almost indistinguishable (both producing about 15 kW of regenerative braking). The regenerative breaking quickly ramps up for L after that (while D remains unchanged).

So are you saying that at, say, 50% state of charge, you can't get as much regen from the brake pedal in "D" mode as you can from letting up on the accelerator in "L" mode? If that's true then it means that "D" mode might be pretty useless for city drivers who want to maximize range.

Thanks for the report, it's very appreciated!

 

[wws]

When I test drove the Bolt, the fellow who accompanied me said max regen was 70 kW (vs 60 in the Volt). In D, it felt a lot like the Volt in D. However in L, it was definitely more aggressive than the Volt. In fact, I rarely found the need to use the paddle in L for extra regen, whereas I use it all the time in the Volt.

 

[Ladogaboy]

Interesting - so you see some amount of regen right down to 0 mph in "L" mode? That would be very impressive.

It's very close. There is a cross over point, but no perceptible increase in power consumption over the car being on and in P. Basically, you just come to a stop and at 0 mph, you have a parasitic draw of <1 kW (with no other accessories on).

So are you saying that at, say, 50% state of charge, you can't get as much regen from the brake pedal in "D" mode as you can from letting up on the accelerator in "L" mode? If that's true then it means that "D" mode might be pretty useless for city drivers who want to maximize range.

Thanks for the report, it's very appreciated!

No, I'm referring to the max regeneration regardless of mode. I can't speak to the brake pedal because that wouldn't be an accurate gauge, but using the RoD (regen on demand) paddle, the max regen under 50-60% SOC increases to 70 kW. Above that SOC, it is only 60 kW (again, regardless of mode).

 

[Zoomit]

No, I'm referring to the max regeneration regardless of mode. I can't speak to the brake pedal because that wouldn't be an accurate gauge, but using the RoD (regen on demand) paddle, the max regen under 50-60% SOC increases to 70 kW. Above that SOC, it is only 60 kW (again, regardless of mode).

So just to confirm, in D mode with the RoD paddle engage, with less than 50-60% SoC, the regen goes up to 70kW? Do you recall at what speeds this 70kW can be generated?

 

[Ladogaboy]

So just to confirm, in D mode with the RoD paddle engage, with less than 50-60% SoC, the regen goes up to 70kW? Do you recall at what speeds this 70kW can be generated?

I want to say yes, but let me confirm that before I commit. Also, it appears to be based on force more than speed. I know I've seen it hit 70 kW at sub-50 mph speeds, but that might have been the result of a decline.

 

[Sean Nelson]

I can't speak to the brake pedal because that wouldn't be an accurate gauge...

Sorry, I'm not understanding what you're saying. In "D" mode when you press the brake pedal (without engaging the regen paddle), why wouldn't the power meter on the dash show how much power is going back into the battery?

 

[Ladogaboy]

Sorry, I'm not understanding what you're saying. In "D" mode when you press the brake pedal (without engaging the regen paddle), why wouldn't the power meter on the dash show how much power is going back into the battery?

The regen paddle only applies regenerative braking force. I'm worried that using the brake pedal could also engage the friction brakes, which might mess with the numbers on the display. It probably wouldn't, but just in case. Also, this information might be in the owner's manual, but if the Bolt EV functions the same as the Volt, your max potential regenerative braking should be available regardless of mode (D+brake pedal, D+RoD, L+brake pedal, L+RoD). The Bolt EV will then dictate, based on the battery's SOC how much total regenerative braking force will be accepted.

 

[Sean Nelson]

The regen paddle only applies regenerative braking force. I'm worried that using the brake pedal could also engage the friction brakes, which might mess with the numbers on the display.

Well that's exactly what I'm wondering about.

Some people have said of the Volt that you can get just as much regen by using JUST the brake pedal as you can by using any of the other techniques. So that's what I'm trying to figure out about the Bolt EV. If you want as much regen as possible can you use JUST the brake pedal in "D" mode, or do you have to resort to using "L" mode and/or the regen paddle?

In other words, if you press the brake pedal hard and the power meter isn't showing as much power going into the battery as it does when you just lift your foot off the accelerator in "L" mode (assuming other conditions such as speed and slope are equal), then we can surmise that the brake pedal isn't as effective in recapturing momentum.

This is pretty much what I'm expecting based on the comment that "L" mode increases range by 5 to 10%. I'm just looking for corroboration.

 

[Ladogaboy]

I believe you can get max regen in either D or L by also using the Regen on Demand paddle. You can also do so with the brake pedal, but that requires being very exact (any amount over will engage the friction brakes).

 

[Sean Nelson]

I believe you can get max regen in either D or L by also using the Regen on Demand paddle. You can also do so with the brake pedal, but that requires being very exact (any amount over will engage the friction brakes).

Here's where I'm coming from: if I use the brake pedal to stop, I'm not worried that much if I only use the friction brakes once the max regen has been reached. The way I figure it is: I need to stop. If max regen isn't enough, I'm not going to just plow into whatever's in front of me in order to try to avoid wasting momentum. The need to stop trumps the desire to be efficient.

So I have no problem if I press the brake pedal so hard that it engages the friction brakes, as long as it's getting as much regen out of the drivetrain as is possible while it does that. If I didn't NEED to stop that quickly, I wouldn't be pressing the brake pedal that hard.

But if the brake pedal only gets, say, half of the maximum possible regen before it starts engaging the friction brakes, then I would probably not want to use it on a regular basis. Instead I would use "L" mode or the regen paddle for normal braking, and press the brake pedal only if that didn't slow me down quickly enough.

So again I ask the question: when you press the brake pedal in "D" mode, can it produce as much regen as simply lifting your foot off the accelerator pedal when in "L" mode.

It's a simple question...

 

[Ladogaboy]

Also, this information might be in the owner's manual, but if the Bolt EV functions the same as the Volt, your max potential regenerative braking should be available regardless of mode (D+brake pedal, D+RoD, L+brake pedal, L+RoD).

So again I ask the question: when you press the brake pedal in "D" mode, can it produce as much regen as simply lifting your foot off the accelerator pedal when in "L" mode.

It's a simple question...

I thought I had answered that. Based on my observations so far, D+brake pedal will produce the maximum available regenerative braking.

 

[Sean Nelson]

I thought I had answered that. Based on my observations so far, D+brake pedal will produce the maximum available regenerative braking.

OK, that's good news. Your previous statement didn't sound all that certain, so thanks for being patient with me - I appreciate your insight.

 

[Ladogaboy]

OK, that's good news. Your previous statement didn't sound all that certain, so thanks for being patient with me - I appreciate your insight.

I'm reluctant to be certain because I'd like to be 100% sure. That is my understanding for now.

And to your previous comments, I have on several occasions had to use my friction brakes to stop. The max regen available near full on the battery doesn't really stop the car the way you would want it to, so you have to use the brakes. :-(

 

[bro1999]

I can also vouch for 70 kW using Regen in L.

 

[Ladogaboy]

I can also vouch for 70 kW using Regen in L.

I believe that will be available using the brake pedal (and D) as well, but we should try to verify when the opportunity comes up.

 

[Sean Nelson]

I believe that will be available using the brake pedal (and D) as well, but we should try to verify when the opportunity comes up.

I'm a little confused as to why there's any doubt about this capability. Can't you just read the power meter on the speedometer display while you're hitting the brake pedal to see how much power is being fed back into the battery? That's basically the question I've been asking. If you stomp on the pedal in "D" mode, what's the maximum shown on the display? Of course you'd need to do it under the same conditions (speed and grade) for which you noted the amount of power regenerated in "L" mode.

It seems like such a simple question - what am I missing?