Electrical Question

I just got a new battery a couple days ago cause the other one was down to 200CCA and was dead twice in one really cold day. Anyway I was checking the voltage of the new battery (12.5v with the engine off) but I am only getting 13.5v with the truck on. So I was like OK but then I looked in the cab to the voltmeter and it was reading anwhere from 13-16. It was 16v right when I started the truck and then went down to 13 after a while. So my question is which meter is right? Everything matches with the truck off but then it's like the voltmeter goes nuts sometimes.

It will go anywhere from 12.5 to 15 when I'm driving down the road. But the thing is that it has been doing this for about a year now. I have never had any trouble starting my truck (besides the crappy battery in the cold) and when I switch on my efan from a stand still it will go down a bit but then come right back, same thing with lights.

Is this normal? has anyone ever had this happen to them? I'd appreciate any ideas that you may have. Thanks.

btw I have a 95 s-10 2.2L 4x2 Man. Trans. 152k

my 88 firebird says 12 while charging on the dash, but reads 13.6 with voltmeter... alwase listen to the voltmeter over the dash, its nothing to worrie about, and as engin speed changes the alt spins quicker, making the charge higher

13.6 is at about the point where the alternator is keeping up with the battery and running everything you need NO problems and is completely normal with a brand spankin new battery. if it goes to 12 or lower get worried. if it goes above 15 for a long period of time get worried. otherwise dont worry ;)