I was driving this morning and all off a sudden my battery light came on, If Im going under 20 its charges like normal, when I pick up speed like anywhere from 35 and up it drops down and the light comes on? and the heater cuts down to nothing, Is this my alternator or something else?> all battery and grounds are tight. and belt is tight? any ideas? and is the votalge regulator in the alternator or is it a box off the side like the chevys?>

91 150 302

 

The regulator is internal to the alternator. Take the alternator off and have it tested. Still very odd that the faster you go the worse it gets, but stranger things have happened.

 

My dads 94 would just decide to turn the battery light on but it never really gave us any problems other than that. Eventually the alternator just went out. I would say to have the alternator tested.

 

I actually saw one with a bad regulator that was charging FULL all the time, it would make the light come on when reved up...

 

thanks boys. I just went for it, and changed the alternator, It used to charge way up in the 15 16 area now its lower, I dont know, All i know is its fixed, now, it may not be chargong up in the top, but its charging. maybe ill throw my group 27 deep cycle in.

thanks again,

 

If you were truely charging in the 15~16 volts you were over charging and would boil the battery. High 13's to low 14ish is fine. Deep cycles dont make good starting batteries.