For a while my volt meter was reading very low for usually the first 15 minutes of my drive to and from work. I did some work on the battery terminals (negative wasn't tight) and replaced my battery to starter cable. After this, the guage read higher then ever before but I still notice that it takes a long time to read in the highest part of the guage. Also, if I turn off my lights (daytime driving of course), the guage jumps up almost 1 volt.

So, my volt meter after starting the car, usually reads I would guess, 12 to 13 v. After driving for maybe 10 minutes it goes to about 14 v and if I turn the lights off it goes to maybe even 15 v.

Overal, I was thinking that my alternator isn't likely doing the best job it could at charging the batter and the battery is likely a bit old and not accepting a charge that well. I figure after 5 minutes at the most, the battery should be charged again because my car starts immediately all the time.

Does anyone else's volt meter read like this or should I start investigating whether I have a problem. For reference, I have an 88 745T.

Thanks