Braking on deceleration
 

I'm probably all wet but I was wondering if you could program your controller to actuate (electric clutch?) an alternator on decelleration or brake application?
The idea being to assist in braking and also help recharge the system 12v battery.
I don't know if an alternator would provide enough drag to be worth it. What do you think? Jim

I suppose you could do a horsepower to watts conversion to estimate the size of the desired "load".

The down side of this is that in a hard stop, brakes process over 1,000 HP. It can be hard to get a battery to accept charge at that rate. On the plus side, most braking can be done at less than 100 HP, especially if you plan it, and even if the system is inefficient, to keep it light, it is better than a total loss.

Would a capacitor accept that large of a charge that quickly?

Seems like if you could get a cap that would handle it, you could use that last bit of braking to aid in your take-off, in the case that you have to... without using any actual pack power.

Just a thought, although probably not a good one.

It is a fine idea. A capacitor could buffer the charge going into the battery, as originally proposed, or help out a traction battery. Being more efficient than the battery, it could not only accept braking overloads, but handle all the stop and go work more efficiently.
A cheaper option might be mechanical storage. Springs are heavier than capacitors for the same energy, but for a 30-0-30 system, they still would not weigh a lot.