The "local" and "online" experts may tell you, that you need to add a "shunt" to your original amp gauge when you upgrade to a modern alternator type of charging system. You do not and here is why….

The advantage of the alternator is the ability to provide an output at idle and low rpms (something the generator could not do) to keep the lights bright and the battery fully charged. The total electrical load of the vehicle remains the same as it was before.

If you read the Alternator Gazette you know the average 6-volt car has an electrical load of about 36 amps with everything turned on.

The total amount of amperage passing through your dash gauge will be the same or less with the alternator because the alternator is keeping up with the electrical load at all times. With the battery always fully charged at all times no large amounts of current will be flowing into or out of the battery as before.

The total amount of amperage passing thru your dash gauge will be the same or less with the alternator because the alternator is keeping up with the electrical load at all times. With the battery always fully charged at all times no large amounts of current will be flowing into or out of the battery as before.

Upgrading to 12-volts…

Now suppose you decide to upgrade to 12-volts and install a 12-volt 60-amp alternator, so you can add a modern stereo and air conditioning. What happens to the total electrical load then?

The total electrical load becomes half of what it was originally because of the electrical rule that says when you double the voltage the amperage load will be reduced by half. So our 36 amp electrical load becomes 18 amps on 12 volts. Do you think you can run air conditioning and a stereo on the remaining 18 amps? Absolutely!

You have plenty of reserve output from the alternator (40 amps, 60 minus 18) and the only current that will flow through the amp gauge in the dash is what is needed to keep the battery fully charged just as before. The alternator will take care of the additional electrical load with no affect on the amp gauge or battery.