Results are in: the mighty Flea requires
60 Watts just to run (11.3v x 5.3 Amps).
That's alternator disconnected, at 880 RPM.
With the alternator connected:
89 Watts @ 2500 RPM (14.1v x 6.3 A)
Turns out I didn't need the parallel/series multimeters. None of the individual systems/components on the car draws more than 10A
Edit - I shouldn't say that - the lights on high beams are around 120 Watts.
SEE: Tested: power draw of Geo Metro accessories & systems (volts, current/amps, watts)
