Quote:
Originally Posted by redpoint5
I'm saying you either misheard, misunderstood, or the engineer was mistaken about regen adding 40 miles of range to a car that would otherwise have 210 miles of total range.
In whatever the EPA test circuit is, I guarantee ~20% of the energy isn't just being wasted by the brakes.
At any rate, the ability to return 80% of braking energy back into useful work makes "technique" relatively unimportant for EV drivers.
11.2 kWh from all regen / 0.16 kWh from 1 regen braking event from 70 MPH to 0 = 70 braking events.
In other words, during the 250 mile trip in a Bolt, on average, a person would have used regen equivalent to braking from 70 MPH to a stop 70 times to have generated 11.2 kWh of regen.
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The engineer is Josh Tavel, Chief Engineer for the BOLT project, Senior Vice President for Energy Storage & Propulsion, General Motors, BS Automotive Engineering & Technology, MS Mechanical Engineering.
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Here's how the numbers work:
1) You begin with an EPA test weight of 3,900-pounds.
2) You drive it at an average 26.6-mph.
3) Every 189.5-seconds you bring the BOLT to a complete halt, at a deceleration rate of approx. 3.3-mph/second.
4) You do this 142.8-times with the 60-kWh pack.
5) You're arresting 2.5628-kW worth of kinetic energy with every stop.
6) With a conversion efficiency capability of 81.1%.
7) Recovering only 94.4 Wh each time.
8) For a total 13,481.89- Wh ( 48,534,806-Joule/second )
9) Or, 13.48189- kWh.
10) Or, 0.40-gallons gasoline-e
11) @ EPA Combined 100-mpg-e
12) = 40-miles.
13) Without regen, you'd be at 160-miles to battery depletion.
14) Regen gets you to 200- miles.
This is only for the 2016-2021 BOLT. No other vehicle.
Please see, CAR and DRIVER, September, 2016, PP.56-59.
You may reach Josh Tavel at, 300 Renaissance Center, Detroit, Michigan, 48265, or call, 800-462-8782.
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PS:
Your source may be confused about how EPA 'COMBINED' MPG, Federal Test Procedure is conducted.