I want to determine the available capacity of the alternator for adding additional loads.
It was suggested, "... that to figure out the actual capacity, get a Big Ass (tm) rheostat and hook it across the battery, set to max resistance, with the bike running at say, 4500 rpm. Put your voltmeter across the battery as well, and crank the resistance down until the voltage reads 13.2 volts. Measure the resistance of the BA rheostat, apply a bit of Ohm's law, and voila, your excess capacity."
Minimum system voltage is 13.5 volts. The alternator has a rated capacity of 400 watts.
Any suggestions what I can use for the BA rheostat?