93 Prism Battery Lite is On

I have a 93 Prism, well it is my girlfriends, but that isn't the problem. Yesterday we were driving it and the battery lite came on but it wouldn't stay on constantly. It would almost always be on accept for when I accelerate, once I let off the gas the battery lite comes back on. So I figured oh the battery must be almost dead, it isn't, atleast that is what Walmart said, I took the battery to them to exchange for a new battery and before they exchanged it they have to test them and their battery tester said it was a good battery.

What could the problem be?

Alternator.

Alternator.

I was kind of thinking that too, but we had the alternator replaced less then 3 months ago.

Go down to Autozone and have them test the alternator on the car, rebuilt alternator often fail if not properly rebuilt. Check the tension of the belt, a loose belt can cause these symptoms..

Also check the pigtail to make sure it is making a good connection :)

Mine broke on me and I was also getting the battery light :)

Might not be the same issue, but just a thought...

I have a 95 prism and had a very similar symptom. The battery light
would come on at random, or at unexplained times. Often on
highway accelerations.

Turns out the seal in my windshield and roof was letting water
into the roof. I found that playing with the interior light switch
several times, while the battery light was on, could make the
battery light go out. Rainwater was getting in and shorting the
interior overhead light, causing the battery light to come on.
If your roof or windshield seal is bad, it could be letting water in.
Check the weatherstrip at the top of the wiindshield...

If your suspicios, remove the bulb in the overhead light, leave the
light switch in the off position, so that opening a door won't trigger
it, and see if the bat-lite stays out.

I sealed the leak between the windshield weatherstriping and roof, then
let the summer heat dry out the inner roof....all set so far.
(but again, might not be your issues, who knows)
My alternator also went once on that car. The battery light was the
first sure sympton too.