I thought I'd pass on some information I've obtained which you'll probably eventually need. Besides, by writing it down I'll be able to find it the next time. I started installing mine in 1995-1996. Lead-acid batteries have a finite life even if not subjected to deep discharge cycles. For the batteries used by APC, this is typically four to six years. As part of the self-test cycle, the UPS measures the voltage of the battery at full charge (which falls as the battery ages), and if it's below about 90% of the value for a new battery, it sets off the "Replace battery" alarm, which it repeats every day. [on apcupsd versions prior to 3.8.0, this message is sent once, on version 3.8.0, it is sent every 9 hours - KES]. You will occasionally get a false alarm. It's a good idea if you get an alarm to repeat the self-test the next day and see if the alarm goes away. If the alarm is persistent, you need to replace the batteries, which can be done without powering down the UPS or load-you just open up the battery door, take out the old batteries, and hook up the new ones.APC makes "Replacement Battery Units" for each of the SmartUPS models, but by a
Another important step is to find a way to shutdown Computer B when UPS 2's battery is low. Probably the simplest way to do this is to edit $HOME/apcupsd/bin/apcupsd.conf on Computer A so that this second copy of apcupsd becomes a network master. Then install a standard slave configuration on Computer B. Please remember that if UPS 1's batteries are exhausted before UPS 2's batteries, Computer B may not be properly shutdown. Thus there are certain risks in such a configuration. That said, these configurations can be very useful for powering electronic equipment and such.