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Discussion Starter #1
Does anyone know, whether regeneration varies with the pressure applied to the brake? I think it should vary and mechanical brakes should kick in in emergency braking? This is a concept that Cocconi (I hope I have his name right) was suggesting to incorporate into EV-1 design. GM did not agree (too complex they thought for average guy to comprehend - really they wanted make money on service). How is that with Volt?
 

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I'm not sure that anyone knows the specifics

Does anyone know, whether regeneration varies with the pressure applied to the brake? I think it should vary and mechanical brakes should kick in in emergency braking? This is a concept that Cocconi (I hope I have his name right) was suggesting to incorporate into EV-1 design. GM did not agree (too complex they thought for average guy to comprehend - really they wanted make money on service). How is that with Volt?
I don't know that anyone has the specifics of the regeneration design. I think that you will see mechanical brakes, the primary reason being that the regeneration system will not be able to handle the power that results from a rapid deceleration (this could change with a more powerful electric motor and batteries). The other consideration is safety in the result of an electrical system failure and remaining stopped on a hill. If you look through the threads you'll find various discussions with regard to regen, including a good discussion on whether or not to coast or emulate "engine breaking" when the driver removes their foot from the accelerator.

I also would be interested in knowing what the peak and sustainable regeneration rates are for the Volt.
 

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Does anyone know, whether regeneration varies with the pressure applied to the brake? I think it should vary and mechanical brakes should kick in in emergency braking? This is a concept that Cocconi (I hope I have his name right) was suggesting to incorporate into EV-1 design. GM did not agree (too complex they thought for average guy to comprehend - really they wanted make money on service). How is that with Volt?
The details of when the regenerative braking kicks in is one of the issues we discussed with the GM engineers at Volt Nation. Essentially, once you take your foot off the accelerator, the Volt can go into "drift" mode or "regenerate" mode, or someplace in between. That's part of the programming that wasn't completely worked out at the time. They were leaning toward having the car go into a light regnerate mode, and then increase the amount of regenerative braking by lightly hitting the brake.

Even with the regenerative braking, the Volt still need mechanical brakes (which thay have said will be electrically activated). A typical car has three times as much braking capacity as acceleration capacity (since the brakes always need to stop the car if the engine throttle gets stuck), and the Volt will be the same here. While the regenerative brakes on the Volt can capture a lot more of the braking energy as parallel hybrids (like the Prius), you'll still need mechanical brakes for safety reasons.
 

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Even with the regenerative braking, the Volt still need mechanical brakes (which thay have said will be electrically activated). A typical car has three times as much braking capacity as acceleration capacity (since the brakes always need to stop the car if the engine throttle gets stuck), and the Volt will be the same here. While the regenerative brakes on the Volt can capture a lot more of the braking energy as parallel hybrids (like the Prius), you'll still need mechanical brakes for safety reasons.
Stuck throttle is not a problem. With an electric, all you need is an inhibit signal coming off the controller. When the brake lights come on, a signal is sent to the controller to cut power to the traction motor. You do not wear out brake pads and you do not burn up the controller or traction motor that way. It also saves battery power. Even my e-bike has this feature.
 

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regenerative drive

Does anyone know, whether regeneration varies with the pressure applied to the brake? I think it should vary and mechanical brakes should kick in in emergency braking? This is a concept that Cocconi (I hope I have his name right) was suggesting to incorporate into EV-1 design. GM did not agree (too complex they thought for average guy to comprehend - really they wanted make money on service). How is that with Volt?
Regenerative braking does not mean you generate electricity only when you apply the brakes, as a mater of fact when the brakes are applied you loose some of the power in form of heat at the brake pads. Regeneration starts as soon as you let go of the acceleration paddle.
 

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Thank you.

;)
 

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Discussion Starter #7
Very interesting concept. That is the reason I asked the question in the first place - How will the Volt work?
In my opinion when you take the foot from accelerator the car should simply coast without using any power as well as it should not generate any energy because that is braking (electric motor will generate electricity by slowing the car). As soon as you touch the brake pedal the electric motor should start regeneration (slowing the car) amount/level of regeneration should depend on the pedal brake application (no physical brakes are applied to the wheels at that time). Only if you apply specific amount of force (ex. emergency braking) then brakes should be applied to the wheels of course with parallel regeneration. That is what I think it should work to allow for maximum energy recovery. Question is, how the car is designed?
 

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Regenerative braking does not mean you generate electricity only when you apply the brakes, as a mater of fact when the brakes are applied you loose some of the power in form of heat at the brake pads. Regeneration starts as soon as you let go of the acceleration paddle.


It does not have too. The brake paddle could be set to deliver progressive regen before the mechanical brakes are applied.

Coast when you let off the accelerator and progressive regen on brake application before mechanical brakes kick it.




 

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This is all just firmware. It can work any way you can imagine, as long as you remain within the constraints of the hardware design (and the laws of physics). I can't wait to see the firmware hacks to be had for the Volt. Ya gotta love flash-based microcontrollers! :D
 

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This is all just firmware. It can work any way you can imagine, as long as you remain within the constraints of the hardware design (and the laws of physics). I can't wait to see the firmware hacks to be had for the Volt. Ya gotta love flash-based microcontrollers! :D
I've got the first hack I'm going to do. A sharp knife to the wire that tells the gas engine to start when the battery pack gets to 35%. Insert toggle switch. That way the gas engine will not start when I am only 6 blocks from the house.
 

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I've got the first hack I'm going to do. A sharp knife to the wire that tells the gas engine to start when the battery pack gets to 35%. Insert toggle switch. That way the gas engine will not start when I am only 6 blocks from the house.
You would void the warranty on a $10,000 battery? Not me. I'll let it do what ever GM wants it to.
 

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It should feel "normal"

Very interesting concept. That is the reason I asked the question in the first place - How will the Volt work?
In my opinion when you take the foot from accelerator the car should simply coast without using any power as well as it should not generate any energy because that is braking (electric motor will generate electricity by slowing the car). As soon as you touch the brake pedal the electric motor should start regeneration (slowing the car) amount/level of regeneration should depend on the pedal brake application (no physical brakes are applied to the wheels at that time). Only if you apply specific amount of force (ex. emergency braking) then brakes should be applied to the wheels of course with parallel regeneration. That is what I think it should work to allow for maximum energy recovery. Question is, how the car is designed?
I think that in order to feel more or less like a "normal" car, the Volt should decelerate mildly when you're completely off the go-pedal. Unless I have the clutch depressed or the transmission in neutral, I expect a bit of engine braking when I release the accelerator, and it makes it much easier to drive smoothly. Otherwise in any sort of traffic you'd be on and off the brakes all the time just to run with unsteady traffic and maintain a gap ahead of you, rather than being able to coast down a little by releasing the accelerator.

Designing for maximum efficiency, they'll probably trim the regeneration in progressively as you release pressure on the accelerator, and (if they get it right) in the process make the car feel very natural to drive.
 

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I think that in order to feel more or less like a "normal" car, the Volt should decelerate mildly when you're completely off the go-pedal. Unless I have the clutch depressed or the transmission in neutral, I expect a bit of engine braking when I release the accelerator, and it makes it much easier to drive smoothly. Otherwise in any sort of traffic you'd be on and off the brakes all the time just to run with unsteady traffic and maintain a gap ahead of you, rather than being able to coast down a little by releasing the accelerator.

Designing for maximum efficiency, they'll probably trim the regeneration in progressively as you release pressure on the accelerator, and (if they get it right) in the process make the car feel very natural to drive.
Yeah I could see why they would make that the default behaviour. Hope they make it easy to modify!
 
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