PEWTRESS, NATHAN JAMES III City/State: St George / UT PCF Number: 195766 Arrest Date: 19:22:00 02/01/18 Agency: St George Police Department RELEASED FROM CUSTODY
then you need a little more rpm to get the alternator to charge above the battery voltage. About 13.5 volts. The average alternator is now between 1,300 to 2,100 rpm. I set up an old 35 amp alternator to run off a 1/3 hp 1,750 rpm washing machine motor at a 1:1 belt ratio. Using the stock regulator would stall the 1/3hp motor. I put a large adjustable resister on the field connection of the alternator.
An original equipment alternator will put out between 60 and 120 amps at 2000 rpm. Let's assume that the headlights, fans, and radio are all on and using up half of this power. So in this worst-case example it is going to take about 20x the amount of time spent cranking or about 10 minutes to replenish the battery. In more realistic scenarios the starting load will be much less as will the cranking time, and the energy used to start the car will be returned to the battery in a minute or two.