The APC Back-UPS RS 1500VA allows you to hot swap the backup battery, but there’s no explicit instructions on how to reset the replace battery warning. In order to reset the the replace battery warning, you have to run the battery test by pushing down the button at the front for a few seconds. Be sure to keep your finger down until the unit starts running its test. If you just quickly press the button, it will just turn the unit off. After the unit runs through the battery test, the replace batter warning will be gone. Finally, don’t run the battery test until the new battery has had sufficient time to charge up. Twelve to twenty-four hours should be fine for the battery to become fully charged.
