Electrical problem
1985 Oldsmobile Firenza 4 cyl Front Wheel Drive Automatic 200000 miles

My car is slow to crank, if I run it for over ten mins, then I have to wait for an hour or so for it to crank fast enough to start. I have tested the alternator and have 13.5V at idle, I also have .2V on both the + & - sides between the alt and the batt. The battery is new and I have done this with a known good battery too. I was thinking alternator, but from what I can see, that isn't it. The charge light is on, but that has been on since I got the car two year ago, this has only been going on for a month. I did find the engine to chassis strap disconnected, but no change when I connected that to the transmission. Any help is appreciated, I am at a loss.