#8514
V8 Staff
Keymaster

The problem is that voltage drops as the accessory gets farther from the generation source because of the electrical resistance in the wire and heat. So, as a test, start your Riv and measure the voltage at the alternator post. Then check it again at the tail light, or at an amp if yours is in the trunk.

The V in the trunk is going to be lower than the V at the alternator.

The alternator has an internal voltage sensor to tell it when to crank up the power per the demand of the accessories, but that internal sensor does not know how much voltage is lost due to electrical resistance. On a 1-wire, the sensor knows the V at the Alt only, and not anywhere else in the system.

Your alternator might be cranking out 13.6V at the charge post, not knowing that your amp is starving at 11.9V all the way in the back of the car.

A system with a remote sensing wire, however, can read the voltage at a junction block or somewhere in the car far from the alternator and report back to the alternator the voltage including the resistance drop across the harness.

This way, it would tell the alternator that the amp is hungry and kick the alternator up to say 14.8V to compensate. This concept works with both internal and externally regulated alternators.

In new cars, the ECM senses voltage and controls the power output based on total system voltage.

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