How does the alternator charge the battery?

irideflatland · 12-06-2005, 05:32 PM

I'm just curious. I thought the only cables coming from/to the battery were the red and black ones. So how does the battery get charged?

my99sl1 · 12-06-2005, 05:53 PM

How it works: A current through the rotor supplied by the battery generates a magnetic field as the alternator spins. The magnetic field cuts through coils of wire and generates a current. The regulator monitors the battery voltage, and varies the current that generates the magnetic field, thus regulating the current that is charging the battery. As the voltage of the battery approaches full charge, the regulator cuts back on the output of the alternator. An alternator can not start charging with a 100% dead battery, although once going, it sometimes can generate an output if the battery is removed. Never try this, the voltage from the alternator can rise, and damage the vehicle's electrical system.