So ive owned my 95 Blazer for about 2 months now and according to the gauge it has always charged a little on the low side. I got the alternator tested and was told it was bad. I just put in a new one tonight but im having the same issue. If im idling or driving around the needle stays about 12-12.5 volts. if i turn up my radio it drops down to about 10. I havent hooked up my multi meter to test the actual voltage, im just going off of the dash. Anyone else have this kind of issue. Any help appreciated.

 

Does it alway start? And you are right, you should check voltage at the battery with you multi meter. If it is low as you think and you have a new alternator i would think maybe a bad ground between body and engine. On the fire wall by ac box is a ground strap that goes down and connects to the back of the right bank of your head. You could take jumper leads and place on negative terminal of battery and the other to body of alternator. See if that makes any difference. Back of head bolt I think is 5/8 not a #10.