Quote:
Originally Posted by aerostealth
I was watching TFL Trucks last night and they were testing a Rivian electric truck towing a flat bed trailer with a large pickup truck on the carrier up to the Ike Gap (from Boulder, CO) and back. I won't post a link here because these guys are seriously aero-ignorant but they had a result I found interesting.
Going downgrade and setting their cruise control to 60 mph they only gained a couple kWh and a few miles of range from the regenerative braking. They were very puzzled by this result. The following occurred to me.
1: Regenerative braking energy returns at speed is a function of aerodynamic drag and rolling resistance.
2: A lower drag shape with all the same parameters (frontal area and mass) would allow more regenerative braking energy returns.
3: That it should be possible to map and graph the potential for regenerative braking energy returns as a function of CDA, mass, and speed.
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Slope and distance are relevant factors as well, and wind speed and direction an additional variable.
As has been pointed out elsewhere, a trailer could potentially increase efficiency if it improves the overall shape to reduce turbulent air.
Obviously, the faster one travels, the more energy is expended overcoming drag forces. Whatever potential energy is available given the weight and slope of the hill can be used to overcome that drag and regen into the battery. Go faster, and you get less back. Set the car to neutral, and 100% of that energy goes into overcoming drag.
The most I've ever regenerated was about 3 kWh, which brought my Prius from empty to full charge while descending from Yosemite.