Hot Rod Tips & TechNot Sure If Your Charging? Posted on May 18, 2012January 30, 2020 by Steve Carpenter 18 May Charging system acting up? With the key off, the system should read 12 volts on a voltmeter. Fire up the motor and it should read at least 13 or 14 volts. If it doesn’t, then you have a problem. Steve Carpenter Dime Store Tools Don’t Have An Oil Filter Wrench?