10Si Series Positive and Negative Ground Alternator, 6V to 12V Output

The Negative Ground 6-volt, 8-volt, 12-volt or 24-volt GM based alternator above is configured the same as the standard 12-volt negative ground alternator. Note the position of the white insulators on the three screws securing the brush holder assembly and voltage regulator. The two lower screws are insulated and the third screw near the top of the photo does not have an insulator. The Standard-Hookup requires an ignition wire to the #1 terminal to activate the alternator. The Self Exciting (one-wire) version automatically turns the alternator on when you start the vehicle and rev the motor slightly. On the self exciting units you can also use an ignition wire at the #1 terminal to start the alternator. If you use the ignition wire to the #1 terminal you will not need to rev the motor to get the alternator to start charging but your no-charge light (if you have one) in the dash will not work. Also the Self Exciting setup used leftover magnetism inside the alternator to tell that the alternator is turning so the Voltage regulator will know to turn on and start charging. If your engine turn to slow (like a tractor) or sits around for along time the alternator will loose this magnetism and you will need to manually "excite" the alternator.

HOW TO EXCITE AN ALTERNATOR . To "Excite" a Negative Ground One-Wire ( Self Exciting ) alternator you must have the vehicle running. With the engine running you run a momentary jumper from the positive battery post to the #1 spade terminal. If you hit the #2 terminal it will not hurt anything so I just put the jumper between both the #1& #2 terminal, just because it's easier. This will start the alternator charging then once you shut the motor off and restart & rev the motor you should not have to re-excite the alterantor.

For the 6, 8, 12 or 24-volt Positive ground application you must wire the alternator like the one shown above. Note the three screws that hold the brush holder assembly and voltage regulator, all three are insulated.

After you have installed the positive ground rectifier you must wire the alternator using the red jumper shown above. The voltage regulator in these positive ground alternators are still negative ground. The only component that makes the alternator positive ground is the rectifier. The red jumper wire is connected between the (negative) "Bat" stud on the rectifier to the ground screw for the voltage regulator. The ring terminal on the red wire must contact the ground clip on the brush holder but be insulated from the screw.

Also, when installing the stator and connecting it to the rectifier as shown above on the right side of the picture where the three nuts are. These 3 stator terminals must be lifted a bit so the rear of the terminals do not contact the finned part of the rectifier. The stator leads shorted to the rectifier or inside case is a common problem.

Once the alternator is complete and installed on the vehicle you may need to excite the alternator for the first time.

HOW TO EXCITE A POSITIVE GROUND ALTERNATOR To excite the Positive Ground One-Wire ( Self Exciting ) alternator you run a jumper from the case (positive power) to the #1 spade terminal on the alternator. With the motor running you momentarily touch the jumper from the case to the #1 terminal, then alternator should start charging. After you have run the vehicle for a bit at above idle speed the voltage should build to around 7.5-volts. As in the negative ground unit you can touch the jumper between both the #1& #2 terminals. Once you excited the alternator you should be able to turn the motor off then restart and rev the motor and the alternator will start charging.