The last time I had my oil changed they did a battery check and the printout indicated that the battery needed charging. So when I got it home I hooked up a charger and it started charging about 8 amps and then tapered down to about 3 after a couple of hours. However I have noticed that when I first turn the key on, the voltmeter slowly goes to about 11 volts, which would be the first bug line then slowly creeps up to just under 14 volts. What has got me it that I have never seen a voltmeter act like this. I mean it would normally go directly to the proper voltage. I have about 50 yrs of electronics behind me, but this has got me stumped. If I had a schematic I could test it out. And No I haven't put a meter on the battery yet, cuz I can't find where I hid it.
Vehicle is a 2dr 2000 LS Blazer

 

if youre talking about the voltmeter inside the truck in the dashboard, its probably just off. i have a 1990 chevy that is way off, key on it reads about 10 then charging it goes up to 12.5 but if you check it at the battery it self everything is reading more acurate. as long as i see that gauge move up from the 10v when i start it i know the alternator is working