[Arcanox]

Technically there is probably a slight efficiency curve with regenerative brakes because there's still a lot of heat loss that's proportional to power transfer, even if it doesn't come from friction. I think the "color circle" turns yellow a bit prematurely; you're still pumping nearly 50 kW into the battery at 45 MPH, which is pretty high on the charge rate spectrum. I ignore the color circle when I'm regenning.

When you hit the brake, of course, it's going to start blending a little bit of friction brakes in before it hits the maximum regen force so that the transition is linear, so it does make sense in that situation.

I have a feeling it's based more on acceleration/deceleration rate than power consumption/generation rate, but it's probably a combination of both.

 

[acarney]

Technically there is probably a slight efficiency curve with regenerative brakes because there's still a lot of heat loss that's proportional to power transfer, even if it doesn't come from friction. I think the "color circle" turns yellow a bit prematurely; you're still pumping nearly 50 kW into the battery at 45 MPH, which is pretty high on the charge rate spectrum. I ignore the color circle when I'm regenning.

Right, the problem is when going 40 or 50 mph and just letting off the accelerator it'll stay green the whole time the car slows (even if I slow to a stop), if I hold the regen paddle then it'll turn yellow after two or three seconds. This makes me think the car is telling me that it's more efficient to NOT use the regen paddle at "high speeds" but instead just use it when going 30mph and slower and you need to drastically slow down, or when going like parking lot speeds and need to roll up to a stop sign.

I have a feeling it's based more on acceleration/deceleration rate than power consumption/generation rate, but it's probably a combination of both.

I actually was also wondering about that. I'm not sure the green/yellow color is showing me the efficiency of REGEN that I'm getting, or of my DRIVING style. It would make sense if it's the driving style because the car is saying "HEY! Maybe don't go 45 or 50 mph if you suddenly have to slow down to 30mph or lower" when using the regen paddle, vs just letting off the accelerator the car can't tell if you're trying to slow down, or just not go any faster....

 

[Insight Refugee]

I've also concluded that the paddle is not efficient. To be fair, we are not talking about a huge difference in total range one way or the other, but given that I also feel that the paddle is a more aggressive stop than I would normally make has caused me to almost completely abandon it. The only use I have for it is related to the OnStar safe driver log ... the paddle gives an aggressive stop that does not trigger a "Hard Braking" entry.

 

[llninja]

Watch the road and stop looking at your DIC (driver information console)!!!

Btw, if you are going to max EV range, try driving in NOrmal D and never touch the regen paddles. You will be pleasantly surprised that regen paddles are a gimmick. They're fun to play with but the variable regen afforded by the brake pedal seems to usually enable longer EV runs. Avoiding regen is better than trying to do max regen.

 

[jbakerjonathan]

Watch the road and stop looking at your DIC (driver information console)!!!

Btw, if you are going to max EV range, try driving in NOrmal D and never touch the regen paddles. You will be pleasantly surprised that regen paddles are a gimmick. They're fun to play with but the variable regen afforded by the brake pedal seems to usually enable longer EV runs. Avoiding regen is better than trying to do max regen.

LOL on the driver information console! Regen captures energy when slowing the car, but it is not 100% efficient (nothing is). Your advice on trying to drive to minimize regen makes sense... as long as you don't become a road hazard (I'm not saying that you are suggesting this). You'll save the most energy that way and you'll travel the furthest on the battery charge.

Did I miss the comparison at 65 mph of using the paddle to slow down vs L? I don't subscribe to there being something different when the paddle is squeezed. Think about it: all that is being called for is more electricity to be generated for that particular rpm. Yes, efficiency may decrease due to heat build-up in the generator, but the same current is flowing through the generator when decelerating from some higher speed when in L and that doesn't change the indicator from green to green-yellow. Some other factor is at play here IMO.

 

[mike100]

There has been a lot of people trying to figure out the strategy of operation on the voltec drive from observation and published info.

The order of regen power from less to more:

1) coasting in drive
2) coasting in low
3) regen paddle
4) using the brake pedal (highest regen if you look at the kw numbers).

In the case of using the brakes lightly, it can regen even more than the paddle, but the balance of the car can be upset on less than optimal road surfaces so it will blend the rear friction brakes somewhat to have a proper brake bias. You can drive with or without the brake pedal and you can feel the temperature of rear brakes to confirm this.

Another curiosity (but not surprising) is that if the car's state of charge is high you don't get nearly the regen back into the battery as you would if you had already gone down the road a ways and the battery needed the juice. You need to drive about a mile or so off a fresh charge before the regen paddle feels strong again.

 

[acarney]

There has been a lot of people trying to figure out the strategy of operation on the voltec drive from observation and published info.

The order of regen power from less to more:

1) coasting in drive
2) coasting in low
3) regen paddle
4) using the brake pedal (highest regen if you look at the kw numbers).

In the case of using the brakes lightly, it can regen even more than the paddle, but the balance of the car can be upset on less than optimal road surfaces so it will blend the rear friction brakes somewhat to have a proper brake bias. You can drive with or without the brake pedal and you can feel the temperature of rear brakes to confirm this.

Another curiosity (but not surprising) is that if the car's state of charge is high you don't get nearly the regen back into the battery as you would if you had already gone down the road a ways and the battery needed the juice. You need to drive about a mile or so off a fresh charge before the regen paddle feels strong again.

The full SOC actions makes sense and I've felt that before and kinda thought that's what was going on. However, the driving in normal having the MOST regen surprises me! I would think it was driving in L (which I've lived in since getting the car) since it seems to kick in more aggressive right off the bat. I rarely "coast" so I wasn't trying to maximize distance traveled before having to touch the accelerator again... but maybe that's the key? (By coast, I mean I know a lot of people that without noticing it seem to speed up to about 38 or so and then let off the gas enough to coast down to 32-ish before they notice that they're going slower then traffic around them and will then speed up again)

Edit: I'm retarded. I was reading that wrong. So L is better (for max regen) to drive in then normal D. However, I still can't figure out why I'm getting "scolded" by the DIC with the yellow circle using the regen paddle vs just letting off the accelerator. The regen paddle also never seems to peak about 35 to 38 kW for me but I've noticed when letting off the accelerator that I'll get up to 50kW (if going fast enough to start with).

 

[mike100]

...
The regen paddle also never seems to peak about 35 to 38 kW for me but I've noticed when letting off the accelerator that I'll get up to 50kW (if going fast enough to start with).

It is largely speed dependent. Try hitting the paddle at 70 mph! power is usually rpm dependent on any type of motor/engine.

also, I have my DIC setup to a different view- I don't get the color change stuff , but it is interesting to question what is the motivation- I have asked the question on how much more losses are there really on 50 amps regen to the battery pack vs 100? Power electronics-wise, I say not too much, but perhaps the total explanation goes deeper when you talk about battery chemistry.

 

[acarney]

It is largely speed dependent. Try hitting the paddle at 70 mph! power is usually rpm dependent on any type of motor/engine.

also, I have my DIC setup to a different view- I don't get the color change stuff , but it is interesting to question what is the motivation- I have asked the question on how much more losses are there really on 50 amps regen to the battery pack vs 100? Power electronics-wise, I say not too much, but perhaps the total explanation goes deeper when you talk about battery chemistry.

I'm pretty sure at 70mph the paddle really makes it go deep yellow, yet again if I just let off the accelerator it stays nice and green. (I rarely use the paddle on the freeway because I can anticipate the need to slow down leaving the freeway or upcoming exit more)

 

[llninja]

There has been a lot of people trying to figure out the strategy of operation on the voltec drive from observation and published info.

The order of regen power from less to more:

1) coasting in drive
2) coasting in low
3) regen paddle
4) using the brake pedal (highest regen if you look at the kw numbers).

In the case of using the brakes lightly, it can regen even more than the paddle, but the balance of the car can be upset on less than optimal road surfaces so it will blend the rear friction brakes somewhat to have a proper brake bias. You can drive with or without the brake pedal and you can feel the temperature of rear brakes to confirm this.

Another curiosity (but not surprising) is that if the car's state of charge is high you don't get nearly the regen back into the battery as you would if you had already gone down the road a ways and the battery needed the juice. You need to drive about a mile or so off a fresh charge before the regen paddle feels strong again.

So to maximize range you would have a similar, but different list

a) coasting in N
B) coasting in D
C) using the brake pedal in D (giving you variable regen)
D) coasting in L
E) using regen paddle if you have it
F) slamming onto the brakes in a panic stop where friction brakes almost immediately kicks in
G) using the brake pedal in N

Stop trying to maximize regen when the goal is to minimize it, except when you are at the top of a mountain with a drained battery. That's the only situation I can think of where maximizing regen is beneficial. If only I could go to work and back downhill both ways....

 

[Arcanox]

I wouldn't necessarily tell people to "stop trying to maximize regen" but rather to try and maintain as much momentum as possible. If you can see that traffic is stopped far ahead, coast until you absolutely have to brake, and then brake using as much regen as possible until you no longer need to brake or until you need to hit the pedal to stop in time. If you can maintain one constant speed instead of speeding up and slowing down, that is going to be the most efficient way of driving. If you have to slow down significantly because of traffic or an intersection, try and do so with 100% regeneration if possible. Momentum is the most efficient way of preserving energy in a vehicle, and regeneration is the next most efficient.

 

[mr_raider]

Total energy captured is the product of regen power by the time. It's the negative area under the power curve (area over the curve?)

Strength of regen must be balanced with how long you hold it. My guess is that paddle slows you down too fast. Maintaining your decel over a longer time would yield more benefit than a short sharp decel.

 

[O'Dell]

I made the determination the first week I had my 2017 LT that the paddle was not very efficient because it can't be modulated. I just drive with very, very light pressure [more a touch than a push] on the pedals, watch traffic ahead, and maintain a long following distance. It worked on two Priuses, a C-Max Energi, and it works on the Volt.

 

[llninja]

I made the determination the first week I had my 2017 LT that the paddle was not very efficient because it can't be modulated. I just drive with very, very light pressure [more a touch than a push] on the pedals, watch traffic ahead, and maintain a long following distance. It worked on two Priuses, a C-Max Energi, and it works on the Volt.

In other words, variable regen from the brake pedal is much better than the two fixed point regents from L and the regen paddle. It's there, use it.

 

[DA\Volt]

In other words, variable regen from the brake pedal is much better than the two fixed point regents from L and the regen paddle. It's there, use it.

Isn't L just as variable as the brake pedal if you feather it's use properly?

In my driving experience, there is a huge difference in behavior and the regen gauge between using the paddle and featuring the accelerator a touch.

Sent from my Pixel XL using Tapatalk

 

[Arcanox]

Isn't L just as variable as the brake pedal if you feather it's use properly?

In my driving experience, there is a huge difference in behavior and the regen gauge between using the paddle and featuring the accelerator a touch.

Sent from my Pixel XL using Tapatalk

It is, but you can brake harder while still using regen with the brake pedal than with L. I use L when I'm in rapid stop-and-go traffic, but I shift back to D if I'm going to be travelling at the same speed for more than a few seconds so I can coast. L also makes the brakes act a little wonky at extremely low speeds (1-2 MPH) because the regen fades out and it tries to overcompensate with the friction brakes.

 

[hellsop]

It is, but you can brake harder while still using regen with the brake pedal than with L. I use L when I'm in rapid stop-and-go traffic, but I shift back to D if I'm going to be travelling at the same speed for more than a few seconds so I can coast. L also makes the brakes act a little wonky at extremely low speeds (1-2 MPH) because the regen fades out and it tries to overcompensate with the friction brakes.

Plus if you're regenning with the brake pedal then if things go sour, your foot is ALREADY on and pressing the brake pedal. You gain about a a quarter second of reaction time not having to switch pedals. It's much easier to train the brain "this one for going faster, this one for going slower" than it is to try to train a bunch of emergency nuances.

 

[mike100]

The topic of regen efficiency always degrades into a hypermiling argument. We get it- coasting and preserving momentum is better, but you can't make the daily commute getting honked at several times twice a day so sometimes you have to slow and stop a little less than optimally.

The question in my mind is the best use of all the regenerative modes when you encounter unplanned reasons to stop. For all practical purposes, I think they recover similar amounts of energy (given the same starting speed), but there is probably a little more electrical loss with higher regenerative currents (more aggressive deceleration), but not enough to really matter unless you are going for a range record. The brake pedal application regens over the widest range of killowatts from low to high and is the most user adjustable, but it will blend in the rear friction brakes as needed. I think the brake pedal is potentially the most 'wasteful', although probably not enough to really matter.

 

[Arcanox]

Plus if you're regenning with the brake pedal then if things go sour, your foot is ALREADY on and pressing the brake pedal. You gain about a quarter second of reaction time not having to switch pedals. It's much easier to train the brain "this one for going faster, this one for going slower" than it is to try to train a bunch of emergency nuances.

That argument goes both ways though, because if you're accelerating and already in L when you need to slam on your brakes, you do get instant braking during the time it takes you to move your foot to the brake pedal. It's only a fraction of a second, but it can still help.