Full stop in low

telveer said:

While a full stop may be practical in a BEV because there is just one motor, the Volt has a separate traction and generator motor. The generator is only 55kW. Volt has to constantly switch between these motors as the vehicle decelerates/accelerates. So, the regen system is significantly different from Bolt, and not a simple software update.

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If MGB is the primary traction motor/generator and MGA is the motor/generator used to extend the Volt’s range by generating electricity when clutched to the gas engine, it would be impractical to use MGA for regenerative braking. That would require clutching it to the drivetrain whenever you took your foot off the accelerator (unless you immediately shifted into N), even in Electric Mode, even if you were moving slowly.

My understanding is that MGB, the primary traction motor, is used for regenerative braking.

Everything is already there to provide a complete stop and hold with the service brakes in a Volt equipped with ACC. It does it all the time when you allow the ACC to bring the car to a stop in traffic. It shouldn't be too hard to allow the car to come to a complete stop on it's own by just releasing the accelerator pedal even if ACC isn't engaged. Right now, if ACC brings the car to a stop, pressing the accelerator pedal or hitting "resume" on the cruise control starts the car moving again. That's the exact way you would want it to work with one pedal driving. All the hardware is in the car, so a few lines of code should be all that is needed to mimic the Bolt style of operation.

You know, I thought the brake mechanism was made by Bosch for both the Volt and Bolt, just slightly different but ultimately can be tailored for different brake feel. I recall the Volt had a short/long setting for hilltop assist so one could assume that regen pedal can eventually apply the brakes automatically to stop you. If this hilltop assist can be set to short/long, why can't it be set to off/on on the Volt at the end of regen? Make everyone happy!

telveer said:

While a full stop may be practical in a BEV because there is just one motor, the Volt has a separate traction and generator motor. The generator is only 55kW. Volt has to constantly switch between these motors as the vehicle decelerates/accelerates. So, the regen system is significantly different from Bolt, and not a simple software update.

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It doesn't constantly switch between them; they both work in unison and are both permanently connected to the output shaft through two planetary gearsets.

Barrydr said:

It would be nice if GM would have the brake lights come on with the use of the regen paddle. Otherwise, I'm fine with the way it functions and don't mind lifting my foot to the brake if needed. Just my 2 cents.

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The brake lights do come on when using L or the paddle.

wordptom said:

If MGB is the primary traction motor/generator and MGA is the motor/generator used to extend the Volt’s range by generating electricity when clutched to the gas engine, it would be impractical to use MGA for regenerative braking. That would require clutching it to the drivetrain whenever you took your foot off the accelerator (unless you immediately shifted into N), even in Electric Mode, even if you were moving slowly.

My understanding is that MGB, the primary traction motor, is used for regenerative braking.

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MGA and MGB are both always connected to the output shaft, and two clutches in the transmission hold different parts together or hold them to the chassis so that certain parts remain still, causing power to be transferred through different paths. MGB is the only one used for regenerative braking, and MGA is the only one used to generate power from the ICE, but both can provide tractive effort. MGA also starts the ICE.

The regen paddle brings it down to 1 mph so thats good enough


But should simply be integrated in the gear selector instead of having to hold a paddle. D+ perhaps. I've been spoiled with a Tesla's heavy regen.

Mr X said:

... I've been spoiled with a Tesla's heavy regen.

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But in a T you HAVE to ALWAYS be in control of that 'heavy regen' by constantly having your foot at work on the Go Pedal.
The Tesla Brake Pedal is ONLY an Old-School Friction Brake Pedal. They didn't have the tech to offer Blended Brakes.

marcusm said:

Seems to me that given the Bolt uses essentially the same control hardware and this is already written into the Bolt code for L mode, GM could easily update the Volt software to provide this option.

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I agree with this. It's not a huge deal, but it is one that comes up pretty much daily for me since I like driving in L.

I didn't realize the brake lights are activated with deceleration in L or using the paddle. Thank you.

Barrydr said:

I didn't realize the brake lights are activated with deceleration in L or using the paddle. Thank you.

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Be lucky the engineers thought of it

This is one thing I don't like about the volt after driving the Bolt. If they have to program it to creep, just remove that code. I have driven lots of vehicles without creep, why does the volt have to?
They should also add code to put the brake light on if you are in drive or low and the car is stopped.

I just drive using ACC all the time. ACC brings the car to a full stop if the lead car stops.

Loboc said:

I just drive using ACC all the time. ACC brings the car to a full stop if the lead car stops.

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That's something new I have not heard about!
Does the cruise control remain active below 25 MPH?

One more reason why I'm not jumping on a Bolt until it has some high tech features like this,,, and Super Cruise.

Norton said:

That's something new I have not heard about!
Does the cruise control remain active below 25 MPH?

One more reason why I'm not jumping on a Bolt until it has some high tech features like this,,, and Super Cruise.

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The ACC is nice for stop and go traffic, and will stay engaged down to nearly zero mph, as long as the car in front of you is still moving.
But you need to be going at least 15mph to engage the ACC cruise control

Sheldon said:

The ACC is nice for stop and go traffic, and will stay engaged down to nearly zero mph, as long as the car in front of you is still moving.
But you need to be going at least 15mph to engage the ACC cruise control

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The ACC is full start -- stop.

Sheldon said:

The ACC is nice for stop and go traffic, and will stay engaged down to nearly zero mph, as long as the car in front of you is still moving.
But you need to be going at least 15mph to engage the ACC cruise control

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Actually your speed needs to be at least 25mph to engage the ACC (each time you start out driving, using the ACC). After that, if you have disengaged the ACC you can resume ACC by tapping the steering wheel button or tapping the accelerator pedal from a full stop or at any forward speed as long as you are not stopped at a 4-way intersection or if the vehicle directly ahead of your Volt is not stopped.

jcanoe said:

Actually your speed needs to be at least 25mph to engage the ACC (each time you start out driving, using the ACC). After that, if you have disengaged the ACC you can resume ACC by tapping the steering wheel button or tapping the accelerator pedal from a full stop or at any forward speed as long as you are not stopped at a 4-way intersection or if the vehicle directly ahead of your Volt is not stopped.

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I think you mean 25 km/hr

From the manual:
ACC will not set at a speed less
than 25 km/h (15 MPH), although it
can be resumed when driving at
lower speeds.

JRRF said:

I think you mean 25 km/hr

From the manual:
ACC will not set at a speed less
than 25 km/h (15 MPH), although it
can be resumed when driving at
lower speeds.

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I will have to try engaging the ACC cruise at 15MPH but I recall that I needed to be traveling faster than that for the ACC to initially engage after having restarted the Volt.

jcanoe said:

I will have to try engaging the ACC cruise at 15MPH but I recall that I needed to be traveling faster than that for the ACC to initially engage after having restarted the Volt.

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I have done this many times if I get caught in a traffic jam without first having my ACC on. I only need a little space between me and the next guy to get over 15 mph and set the ACC.

marcusm said:

I really wish that they would reprogram or offer a software update to have the Volt come to a full stop using regen rather than creep in low. The creep although doing exactly what it is designed to do —- mimic a gas automatic transmission— is irritating in this car and my leg gets tired of the brake pedal, which given the strong regen and the regen paddle I really only use now otherwise for sudden stops. Since they apparently implemented this in the Bolt in low, I assume there is no hardware related reason they couldn’t have that code deployed in the Volt? Really wish they did...


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I don't think GM wants you to sit at a light holding the regen. You need to hold the car with the hydraulic brakes in case you are rear ended. Holding regen would send you into oncoming traffic after a rear collision.

Cobalt60Volt said:

I don't think GM wants you to sit at a light holding the regen. You need to hold the car with the hydraulic brakes in case you are rear ended. Holding regen would send you into oncoming traffic after a rear collision.

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Interesting point. I think this is the case with the Bolt, though. Anybody know if that is addressed in the Bolt?


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