I have a 1995 golf TDI the battery light stays on why

Hello and welcome to FixYa!

If the battery light is on, I strongly suggest that you have the battery charged. It can be an indication of a weak battery or a faulty alternator. If the battery light still on after charging then the problem will surely be on the alternator itself. If that's the case the alternator should be replaced to resolve the problem.

If the battery won't hold charge even on a new alternator then the problem will be on the battery itself. It surely is in the end of it's service life and replacement will be necessary.

You may try to reset it to by removing the positive battery connector, letting it sit for at least 5mins. then reconnect it again. This will reset the system and can get the battery light off.

Hope this helps and thank you for using FixYa! Have a good one!