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Discussion Starter #1
OK, so is there a way to tell when the brakes are engaging vs. just using the power regeneration wrapped around the front axles? I run the Classic Enhanced display and the green leaf turns yellow when I press the brakes too hard. I also feel a change in the braking right at that point where the leaf turns from green to yellow.
 

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Yes, yellow indicates when friction braking is taking place.
 

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Yes, yellow indicates when friction braking is taking place.
Nope. Unless you are panic braking, the friction brakes don't engage except below 5 mph or so (or braking any time in neutral). Braking somewhat hard to cause the green ball to turn yellow may still be all regen.

The bottom line is, don't worry about it. I've driven my volt 80k miles using the brake pedal and almost never using L to avoid the brake pedal, and neither the front or rear brake pads look worn at all. In my ice vehicle, I'd be watching every 20-30k miles or so and replace the brake pads before they are worn to the steel bracket. Don't change your habits in a futile attempt to save brake pads. Also don't change your habits to always regen thinking that you're maximizing range by maximizing regen. With 4 years of experimentation under my belt, you maximize range by maximizing momentum and minimizing regen.

Finally, the car is a whole lot of fun to drive it like you stole it and be damned with hypermiling. You can drive like jeff Gordon and still better than any other hybrid out there. Live a little. Drive it like a jackrabbit.
 

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On the gen 1 it's displayed on the green ball. When the leaves stop rotating the friction brakes are being applied. Can't speak for gen 2, sorry.
Except when you are stopping, please don't look at your DIC, look at the stopped car in front of you so you don't rear-end them.
 

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Discussion Starter #7
Nope. Unless you are panic braking, the friction brakes don't engage except below 5 mph or so (or braking any time in neutral). Braking somewhat hard to cause the green ball to turn yellow may still be all regen.

The bottom line is, don't worry about it. I've driven my volt 80k miles using the brake pedal and almost never using L to avoid the brake pedal, and neither the front or rear brake pads look worn at all. In my ice vehicle, I'd be watching every 20-30k miles or so and replace the brake pads before they are worn to the steel bracket. Don't change your habits in a futile attempt to save brake pads. Also don't change your habits to always regen thinking that you re maximizing range by maximizing regen. With 4 years of experimentation under my belt, you maximize range by maximizing momentum and minimizing regen.
Thank you. After reading here on maximizing range I stopped trying to use regen for this purpose and went back to my previous driving styles, which incorporate the mild hypermiling techniques taught in all driving schools. I do use L when appropriate but that's my manual transmission instincts kicking in.

Finally, the car is a whole lot of fun to drive it like you stole it and be damned with hypermiling. You can drive like jeff Gordon and still better than any other hybrid out there. Live a little. Drive it like a jackrabbit.
Not most days on my daily commute. But some days I do drive in binary mode - foot off floor, foot on floor with the pedals providing cushion. This car can definitely be a lot of fun to drive. :)
 

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is regeneration from all four wheels or just one pair?
Regen only comes from the front wheels. Rear wheels are just along for the ride, and very occasonal braking. They are not connected to the drivetrain in any way.

Thank you. After reading here on maximizing range I stopped trying to use regen for this purpose and went back to my previous driving styles, which incorporate the mild hypermiling techniques taught in all driving schools. I do use L when appropriate but that's my manual transmission instincts kicking in.
Every vehicle I've owned before the Suburban and the Volt had manual transmissions. Even my CTS has a 5 speed stick shift on it as this was when Caddy was targeting the 5 series owner's. I wish there was something they could do to pull out all this fancy clutching and give me some gears to shift through, a clutch, a coast in neutral button, and a separate variable regen paddle so the brake pedal means only friction braking. I understand that most Americans can't drive a stick shift, but there are a few of us who prefer it and could easily handle all these controls.

I thought these new-fangled cars stopped for you. :rolleyes:

I can't take my eyes off my cell phone long enough to look at my DIC. It's sad really. I used to have a good relationship with my DIC.
Your inner Elemental is showing.

As for looking at your cell phone, maybe the next Tesla won't have a touch screen at all, so you have to supply your own android or iOS phone/tablet/phablet for the dash. But a better way to make a dash might be to have a really wide touchscreen, something that is 6-8 inches high but 3-4 feet wide. So instead of having multiple screens of different controls, you get it all. Battery/efficiency gauges on the left, speedometer and vehicular status centered to the driver, maps just right of the driver, radio and climate controls near the center of the car, and a separate browser for the passenger to help navigate as well as search for attractions, shopping, restaurants, etc. Add a camera in the dash, and the browser for the passenger can switch to a digital mirror for a quick check before exiting the car. I think this would be much more useful and safer than having to try to look at and press touch screen buttons while driving.
 

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Discussion Starter #10
is regeneration from all four wheels or just one pair?
My understanding is it's just the front axles. Makes me wonder if what I'm feeling is the rear brakes engaging to stabilize the car during harder braking.
 

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is regeneration from all four wheels or just one pair?
My understanding is it's just the front axles. Makes me wonder if what I'm feeling is the rear brakes engaging to stabilize the car during harder braking.
A lot of people seem to think regen uses a special module or whatnot, but it's really just the same drivetrain that makes you go forward, just running it in reverse to slow you down (to state it oversimplified)

So whichever wheels are driven by electric motor to make you go, are also wheels that can pull energy back in to make you stop.

In the case of a volt, that is front-only as it is FWD.
AWD vehicles, such as tesla D variants, are therefore able to regen brake from all 4 wheels at once.

Without the regen on all 4 wheels, the rear brakes will be applied to stabilize as determined by ESC.
However this is typically not during pedal-off regen (i.e. L), only when the brake pedal is applied and it is blending regen with friction brakes.
 

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AWD vehicles, such as tesla D variants, are therefore able to regen brake from all 4 wheels at once.
It's probably worth noting here that 4-wheel regen doesn't double the amount of energy recovery over 2-wheel, any more than a 4-wheel drive vehicle needs twice as much energy to accelerate. (I'm ignoring small differences here such as the added weight of the motors or the need to have the vehicle's electronics able to handle the power levels needed for acceleration and deceleration).

It's the same energy output or recovery, just spread out over 4 wheels instead of two.
 

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OK, so is there a way to tell when the brakes are engaging vs. just using the power regeneration wrapped around the front axles?
Not sure what you mean by "the power regeneration wrapped around the front axles," but to expand on what canehdian said, think of it this way.

When the foot is on the accelerator pedal to accelerate or to maintain speed, electric current flows through the coils of the Volt’s primary traction motor to turn the shaft, and the motor’s shaft turns the wheels via the drivetrain to move the car down the road.

When the foot is taken off the accelerator pedal, that drivetrain connection between the wheels and the motor allows the process to be reversed. The momentum of the car is now turning the wheels, and, via the drivetrain connection, this then can turn the motor’s shaft, reversing the process and transforming the motor into a generator. Using the car’s revolving wheels to apply torque to turn the generator shaft consumes the car’s momentum, reducing the speed of the car. Adjusting the electrical circuits modifies the rate of generation (e.g., D, L, paddle, or variable via the brake pedal), which increases or decreases the torque needed to turn the shaft, and thus how fast the car slows down. Braking regeneration is a convenient and effective alternative to friction braking.

Braking regen has the added benefit of generating electricity to recharge the battery, which recaptures some of the battery power used to accelerate the car (from a standing stop, or from one speed to a higher speed).

Battery power used to maintain speed is irrecoverable (i.e., the amount of regen you obtain by taking the foot off the accelerator pedal does not depend on the length of time you have been driving at that speed).

I’m not sure if both motors are used as regen generators when the Volt is in two-motor or power split configuration, or if the regen operation is limited to the primary traction motor only (yes, regen happens in Extended Range Mode, too). As Sean Nelson points out, increasing the number of regen generators doesn’t increase the amount of regen captured. It just increases the number of generators used to recapture some of the power used to accelerate the car.

Maximum fuel efficiency is achieved when the use of fuel to accelerate the car is minimized. Note that using L or the paddle instead of D to get closer to the restriction point before slowing down (e.g., a traffic light that may or may not turn green by the time you get there or a stop sign where you must stop) may create regen at a higher rate for a short period of time, but it may also be preceded by a longer period of maintaining speed before you reach the slow down point (i.e., irrecoverable power consumption may offset any higher rate of regen gain).

The Volt’s rear wheels have no connection to any motor/generator, and no braking regeneration is created there.

Downhill regen is similar to level-ground regen, but gravitational energy, rather than battery energy used to accelerate the car, is providing the car’s momentum. The downhill momentum uses the wheels to turn the generator shaft, can continue until the car reaches the bottom of the descent, and the process provides a braking effect on the car.

Gravitational forces complicate regen analysis. Much uphill driving is done while maintaining speed (irrecoverable battery power use for the horizontal driving portion of the power consumption), and much of any power used to accelerate uphill will also be lost because gravitational pull replaces some or all of the braking regen whenever the car slows or stops. This makes it more difficult to determine the portion of the battery power consumed for the vertical portion of the bottom to the top of the hill driving that may subsequently be recaptured by downhill regen. The analysis is further complicated by whether or not the car can continue "coasting" as the terrain levels off (i.e., no stop sign of traffic light at the bottom) until power is again needed to maintain speed, and whether or not the terrain is rolling hills, whereby the bottom of one descent is closely followed by another ascent.
 

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When the foot is on the accelerator pedal to accelerate or to maintain speed, electric current flows through the coils of the Volt’s primary traction motor to turn the shaft, and the motor’s shaft turns the wheels via the drivetrain to move the car down the road.

When the foot is taken off the accelerator pedal, that drivetrain connection between the wheels and the motor allows the process to be reversed.
Conceptually, sort of. But the connection between foot on/off the accelerator and traction/regenerative braking is not that simple.

The accelerator, brake and paddle are all inputs to the computer that decides whether and how much to accelerate or brake.

The computer tries to make the Volt feel like an ICE car, it seems to me. And an IC engine can be braking a car even with the foot slightly down on the accelerator.

So on the Volt, regeneration can occur with the accelerator depressed slightly. It's obvious in L, but also happens in D.
 
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