Code 11 and now fast battery drain 2001 E825

Hi would anyone happen to know why my 2002 gem e825 makes a beeping noise when I plug it in to charge ? It still runs perfectly fine but only beeps when I plug it in to charge

It may be running for now, but it probably will not for long.
It sounds like your charger has an issue.
Does your LED on your dash still work It is probably flashing a color or two along with the beep.

What are those colors?