Thanks for the clarification. You do need a "marker" for when to stop the gen, that lets you get through till the next recharge. It seems like you can use the kill-a- watt for that once you have done a few test runs to confirm your marker. Interesting approach.
I once was going to develop a marker using just voltages. Take the battery voltage and the voltage at the charger to see the voltage drop, which gets less as amps taper. You could find the amount of drop that corresponds with the amps you want to be at for your say, 90%. Might work in theory, but then I got the Trimetric, so I didn't care anymore :)
