(ET) Massive sparks on decel

[Christopher Zach <cz alembic crystel com>]

Interesting thing: My Vicor DC-DC power supply caught fire a few months 
ago and died (I used it to power an E-meter). This afternoon I was 
driving the Elec-trak and heard a *snap* under the hood every time I 
stopped the motor. Checked, there was a 1 inch spark going across what 
was left of a capacitor on the Vicor's power supply board.

Looks like something from the motor, but what is generating that much 
voltage? And is there a MOV I can put in to stop it?

Or is something seriously wrong?

Chris