USING A VOLTMETER, SET IT TO A 20 VOLT DC SETTING----PUT THE BLACK LEAD ON A GOOD GROUND---USE THE RED LEAD AND CHECK THE TERMINALS ON THE REGULATOR---SOMETHING SHOULD REGISTER HIGHER THAN THE VOLTAGE YOUR BATTERY HAS---USUALLY IT COULD BE 15 OR MORE VOLTS---IT'S THE JOB OF THE REGULATOR TO REDUCE IT SOME, AND "STEADY IT UP", SO THE BATTERY CAN CHARGE CORRECTLY