I have a sapphire 870 and just looked through the books, nothing warning about a battery back-up. I do have my alarm warning as set on so that it beeps when thread is running low or main engine overloaded, etc. However there is an option if you have it on your machine, go into the set menu tools, and scroll down & unclick the alarm, and see if that makes a difference. I think you should always leave it turned on to warn you, but just as a check to see if it would stop beeping you could try to turn it off?