On Car Test

Install a battery post adapter at the positive post of the battery. Connect voltmeter across the battery. Connect a tachometer to ignition system. Make sure all electrical accessories are turned off. Start engine with battery post adapter switch closed; open switch as soon as engine is started. With engine speed at 2500 RPM, load system with 1/4 ohm resistance. After voltage reading stabilizes, any reading between 13.5 and 14.8 volts is satisfactory.