GM Alternator

[zeitgeist57]

I was told at some point that most GM alternators do NOT charge at idle. You have to be revving at a certain point...or the electrical system needs to fall below a certain voltage...before the alternator decides to kick in and turn that spinning pulley into a power generator for the batteries.

 

If that is the case, can I wire up a switch to the link in the back of the alternator so, if at idle, I can have it charge my system?

 

Vehicle is a 1982 Chevy Silverado with a 6.2L diesel...dual batteries...with cold weather, I need all the juice I can muster to start it up!

[92dropgt]

what?

[Cordell]

If that was the case you would have 12 volts at idle. Besides pushing the output of the alternator without spinning it faster would greatly reduce it's life.

 

I guess you could say the alternator isn't putting out much at idle, but it's that way for a reason.

[Dave1647545494]

all alternators charge at idle if your not seeing at least 13 volts you have a problem

 

if you suspect the alternator I think advance still checks them on the car for free

[zeitgeist57]

I'll check the charging system output after the holidays. I'm probably overlooking a drain in the electrical system somewhere. Thanks, guys.

[Guest 614Streets]

Some alternators Exciter wire , which is power supplied to the field windings to strengthen the magnetism of the rotor , is self excited when the engine is revved to a certain speed.

 

The Exciter circuit runs through the Ignition switch to the the batt or alt dummy light on the dash and to the alternator. If you turn the key on and no batt or dummy light illuminates on gm , then its possible the exicter circuit current is broken. The dummy light goes off once the engine is started and the alternator puts out a charge because the exiter circuit in the alternator also has a diode which is a one way valve and it (the circuit) see's power from the alternator once started and generating.

 

The Alt turns the dummy light on this way.