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[Doug S]

You're probably not going to get anywhere near 50% of that nominal capacity, again because caps don't discharge like batteries. After you've drawn 50% of the cap's energy content, its voltage has dropped by 29% (there's a square law involved). Without some tricky management by the BMS, that puts it well below the battery voltage, and because of the other square law involved, (motor power output drops as the square of the applied voltage, if you're max'ed out at the supply voltage), you're down to 50% of the full-voltage horsepower, as well.

Sure, you could theoretically isolate the ultracap and battery from each other, design some fancy electronics to step up the battery voltage to a higher capacitor voltage, and use just the ultracap for a few seconds once in a while, but that's some high-power (and high-intelligence) circuitry that's going to be fairly heavy, is going to need to be cooled and will take up space on the bike you could just use for higher battery capacity.

And again, batteries are giving higher and higher peak current outputs all the time. I wonder if all this exercise really works for your benefit in the final analysis.

[Frank]

I agree that modernLiPo's out there now (I use some of them for drag racing) have outstanding power characteristics but they do suffer in energy storage somewhat because of this.  I don't think one could just throw caps at an EV but what if the controller was fed only by caps and the battery kept the caps charged up in the "downtime"?

Regardless, it's possibly a needless complication.  Even mediocre batteries have better discharge characteristics these days but it could be like an electric "hybrid".  There would have to be a significant advantage to offset the extra cost, weight, etc. though.

[NEW2elec]

This is a rather long video about Skeleton where he talks about the advantages of using UCs with batteries for the short charge and discharge cycles of braking and acceleration.  The first part is pretty basic but he will get into the other benefits of the setup later on.
To me it's like pulling back a bow going into a tight turn where you have to slow way down by hooking the string on an imaginary pole and then shooting the arrow as you come out of the turn with out having to use your strength (battery power) to fire the arrow.  A short burst of power from more fully capturing the kinetic energy in the braking.

[Crissa]

Yeah, the UCs have the potential to vastly increase energy efficiency in race conditions which translates to urban stop-and go (which EVs are already really efficient at) and twisty/hilly terrain (which EVs are not).

Capacitors just don't have the resistance that batteries do against absorbing energy in burst situations; and don't take wear from fast discharge like batteries do.

-Crissa