I have read and heard many different numbers about it and after owning my Tesla for more than 2 years I wanted to test it out. Here is what I found. I hope this video helps understanding regen a little.
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Short tests don't give you a reliable measurement. For no reason that I can understand, the display gives back regen miles in chunks of 3 (occasionally 4) miles at a time. Drive to the top of Pikes Peak from the Colorado Springs SpC (30 miles), it takes 79 rated miles. Coming back down, I got 22 miles of range back, but it displayed unchanged range for a while then went up by 3 miles, again by 3 miles, 4 miles, then 3 mile chunks for the rest of the drive. (There's only about a mile or two at the end of the drive back to the springs that's not down hill.)
That one guy who was drag racing figured that you can reclaim 70% ish on a single run. So there is that.
So, if I gained about 5.2 kWh, out of 5.8 kWh "available", that's a regen efficiency of somewhere around 90%. If I'm right, this is quite good!
Well, there are plenty of assumptions in my calculations, so 90% might not be right. But based on the metrics I'm using, I'm not seeing how that figure could be way, way off, either.That would be good but impossible. Just the fact that the drive train (motor/inverter/battery) is in best case about 80% efficient, should be enough to realize that you can't capture 90% of the energy. As I showed in my video, you always have the losses inherent to driving. Tires, aerodynamics and other things. There is no way you can capture 90%.
<-- not an expert, but this doesn't pass my common-sense test. It seems you're comparing 2 different things and getting the same ratio and saying that based on that ratio your conclusion is valid (I'm not arguing if your conclusion is valid or not)This is from Tesla's blog. For example, look at 40 mph (the speed I was going at for my test) and the energy usage. approx 110 is lost in tires, air drag and ancillary. Total is about 175. Subtract that from the total and you only have 33% is available at all for regen. Sounds strangely similar to what I was getting
I have read and heard many different numbers about it and after owning my Tesla for more than 2 years I wanted to test it out. Here is what I found. I hope this video helps understanding regen a little.
When you're accelerating you're fighting air drag and tire friction (so these are losses). When you're decelerating those items are helping you (they wont help you regain kwh to your pack, but they help you slow down), so they're not really loses here.