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Frank F

100% regenerative braking

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On the few times I get 100% recovered energy when braking, does that mean the hydraulic brakes were not applied at all? I.e. 100% of the braking is regenerative; pads didn't touch rotors?

 

Likewise, is the percentage linear in that 75% recovered energy means 75% of the braking was regenerative, 25% hydraulic?

 

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100% recovered energy means that you recovered 100% of what it was possible to recover. It says nothing about friction braking. It is not possible to bring the car to a complete stop using regen only because the slower the wheels turn the less regen is available. You could probably do it if you were headed up a steep hill but you would start rolling backwards unless the friction brakes were applied.

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100% recovered energy means that you recovered 100% of what it was possible to recover. It says nothing about friction braking. It is not possible to bring the car to a complete stop using regen only because the slower the wheels turn the less regen is available. You could probably do it if you were headed up a steep hill but you would start rolling backwards unless the friction brakes were applied.

Excellent explanation. Thank you.

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It also means that you recovered 100% of the 30% available due to regenerative braking, not that you recovered 100% of the energy.

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It also means that you recovered 100% of the 30% available due to regenerative braking, not that you recovered 100% of the energy.

Interesting point. I have often wondered how much of the kinetic energy is actually captured after accounting for friction, tires, parasitic losses etc. Your figure of 30% sounds plausible to me but I'm wondering if you saw that documented somewhere?

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That's a good question. How much can be recovered? I'd imagine it'd be a pretty significant percentage with the percentage possibly increasing the faster the vehicle is going up to a certain point. I envision a bell-like curve if plotting the percent that can be reclaimed on the y-axis and initial speed on the x-axis. Because the drag on the vehicle is proportional to the square of the speed it would seem that at some point the drag force would be faster to act to slow the car than the magnetic force in the transmission. That's why I'm thinking there is a speed at which the regen effectiveness is maximized. Seems like 30% is pretty low though...

Edited by bdginmo

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It also means that you recovered 100% of the 30% available due to regenerative braking, not that you recovered 100% of the energy.

Yes, good point. There's always going to be some loss on conversion of energy which (I hope) the 30% takes into consideration.

 

Did I just confuse myself and everyone else?

 

<Edit this yet again :)>

 

I believe you're saying that the maximum amount of braking due to regenerative is 30%. And when we hit those 100% marks, 30% of the braking is regenerative, 70% hydraulic.

 

So a 50% braking score would be 15% regenerative, 85% hydraulic.

Edited by Frank F

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I think that's what griswald is saying. But the 30% may have just been an example. 30% seems awfully low to me. When I put my Energi L the decel force when I let off the throttle is substantial and it's not using friction brakes. At 45mph I would imagine the amount that could be reclaimed if doing it perfectly is closer to 90%...just a guess though.

Edited by bdginmo

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