1974 Baywindow battery draining

['57 Oval]

My baywindow has developed a new gremlin over night. It starts and runs just fine, but when i switch it off and remove the key from the ignition the battery light comes on on the dash. This light stays on and eventually drains the battery.
Any ideas what would cause this?

Thanks in advance

[Tony Z]

I had the same issue a few weeks ago, after doing an engine swap. I checked and double checked everything I touched....
needless to say, it was the ignition switch that failed while I was busy doing other things not related to it....

[retrovan]

Could also be your voltage regulator that has got stuck, or if its electronic, burnt out.

Test your charging with voltmeter, and see if it regulates the charge rate.

Herman