Regen Management - Gas vs Brake

[rmay635703]

That's a good point. If you coast at high speed, you're loosing that energy only to friction for a longer time. If you regen brake, you gain back some of that energy, and coast after some threshold, you could maximize energy usage.

I would like to see some math on this.

Hypermilers do this but normally not for this reason, if you brake hard and early it is less likely you will have to stop and therefore have conserved momentum which is MUCH more efficient than coming to a stop by either means.

[Skotty]

So this thread kind of wandered off from my original topic, which was to question about doing regen as part of gas and/or brake operation. Anyway, I have some new information, thanks to the just posted engaget video of driving the Tesla Model S. According to what they were talking about in the video, the Model S does indeed do all regen as part of the gas pedal operation, leaving the brakes as traditional friction brakes only. Also interesting, they said the Model S has an accelerometer and will kick on the brake lights after exceeding some deceleration threshold.

Video here: http://www.engadget.com/2012/06/22/t...goes-electric/

[QB 45]

Correct me if I'm wrong (LOL), but if I remember correctly, I think it was WopOnTour that said in "D", 20% of the regen is in the gas pedal, and 80% in the brake pedal, and in "L" it's 80% in the gas and 20% in the brake (before the transition to the friction pads).

It could be a total misfire on my part, but I think this was the ratio. I'm just glad GM made it so darn easy to switch between these modes on the fly!

[saghost]

Correct me if I'm wrong (LOL), but if I remember correctly, I think it was WopOnTour that said in "D", 20% of the regen is in the gas pedal, and 80% in the brake pedal, and in "L" it's 80% in the gas and 20% in the brake (before the transition to the friction pads).

It could be a total misfire on my part, but I think this was the ratio. I'm just glad GM made it so darn easy to switch between these modes on the fly!

I think it varies somewhat with speed, but in my experience if more like 10-15% in D and slightly over half in L. See the three rising diagonal lines in the top half of the chart? the lowest one is D regen, the middle one is L regen, and the top one (almost at the edge of the chart) is max regen using the brake pedal...

Opel_Ampera_Power-Speed-Histogram.jpg