On my 88 Accord LX the battery quit and after charging, the dash battery light stays on even with the key out. The battery was old and didn't hold the charge well so I got a new battery. Well the dash light still stays on and the battery will drain over night.
I've pulled all the fuses and the light stays on.
After starting the engine the dash light dims but is still on. Also the oil light is on after starting and the oil is full and the car runs fine.

Any ideas of what to look at next?

 

You have a drain on your battery. That's why it dies overnight. You must find it for your car to be good again. It won't be easy. Think of all the wiring you have modified and double check it. Check all your grounds and use a multimeter to help you find the drain.

Good luck.