Back English pronunciation Jan 22, · tomf 10/ 23/ 4: 20 PM ( in response to Kevin). hello, i have two APC UPS devices ( both are Back- UPS RS 1000). i also recently started hearing that one- minute long series of rapid beeps from one of the units, every 5 hours or so ( it' s quite annoying). I have two of these units with the same fault and I have also read about this problem on usenet. The problem is that the Back- UPS RS 500 stop charging the battery.