battery light on after shutting 560SL off

[zeus2112]

Hello,

I turned the car off, and the battery light stays on. If I start the car, it goes off, but as soon as I take the key out, that light goes back on.

also noticed a humming/buzzing noise that seems to be coming from the battery area of the trunk. This happens before I put the key in and start the car. Not sure if its related or not.

any insight would be appreciated

thanks