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Comment by arghwhat

7 years ago

Peak dissipation is not particularly interesting in this context.

That current is charging the battery—not dissipation. I have no idea what kind of energy the friction brakes dissipate (that's not reported on the dash like regen braking is).

  • From the perspective of braking a motor, charging a battery is just a way to dissipate energy. A bad one at that, considering that there must be ample room for charge, and the charge rate must be limited.

    Sports cars dissipate several hundred kilowatts in their friction brakes (for reference, the Porsche Taycan which can almost do with only regen braking can regen ~270kW). A hard-braking truck will exceed this significantly, but of course distributed over many more brake discs.

    However, for the trailer scenario, I assume that if you go up a certain slope using N kilowatt of propulsion to maintain a stable speed, you'd need somewhere in the ballpack of N/2 killowatt of braking power when going down during the full duration (unlike hard braking, which is only for a few seconds).

    • I'm not following some of your logic (especially the "bad one" part). Unless you start your journey downhill (which does apply to some people, I realize), you should always have room in the battery to store whatever energy you're dissipating—you had to get the energy to accelerate in the first place from somewhere, after all.

      Also, peak braking performance is much different than effective regen potential, since you shouldn't need to do hard braking very often.

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