LanghamP Posted November 13, 2019 Posted November 13, 2019 Suppose you lose or pop your charger. Is it worthwhile walking up a hill a few times then coasting down on your wherl? If so, how many times? Or are you better off water skiing behind a friendly car? Regenerative braking may be surprisingly effecient.
Aneta Posted November 13, 2019 Posted November 13, 2019 Let's see. Suppose, your weight with the wheel is 100kg, and the efficiency of converting potential energy into battery energy is 50%. Then going down 1 meter (of elevation) will charge battery by 0.5*mgh = 0.5*100*9.8*1 = 500 Joules. 1Wh is 1J per second times 3600 seconds, so 1m of elevation loss will charge the battery by 500/3600 ~ 0.15Wh. To charge 1000Wh battery, we need 7200m of elevation! Basically, we need to climb Mt. Everest and ride it down to fully charge a 1000Wh battery.
Mono Posted November 13, 2019 Posted November 13, 2019 On the other hand, descending 100kg with 1km/h (that is going down a 10% incline with 10km/h or a 5% incline with 20km/h) gives 273W back from potential energy. That's the same order of magnitude that a standard charger provides to the wheel. Of course it does take many hours to fully charge a wheel, but it is a relevant amount of energy for potential charging.
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