something maybe wrong w/ electrical system...

[93v6firebird]

the charge to my batt from my alt seems to be too low, it used to be well above 13, however recently it has dropped... w/ A/C on and stereo it is a bit about 13 and at idle it has dropped a needle width BELOW!!
it starts easily, doesnt have to crank a whole lot or anything..
I was wondering if the alt brushes are getting worn? or the diodes??
anything else could be wrong?
thanks for your help!

[AMinor65]

If you have high powered stereo, turn it and the amps off then retry. If it still does it, alternator is about to go.

[93v6firebird]

w/ the stereo and A/C off it is still lower than it used to be.

[Blizzard96]

When I start the car in the morning, my voltage is almost at the 3/4 mark... alittle lower. By the time I get to work, it has lowered...is this normal? It is usually a little above the 1/2 afterwards...

THought when I put it in reverse, the voltage drops (if i have my lights on, they dim) then goes back up.

[93v6firebird]

basically the same thing for me

[Fat_kid_in_little_camaro]

Could also be your batteries. I'd have it both tested at a place like Autozone. its free and takes like 5 minutes.