My trusty CyberPower CP1000PFCLCD UPS was starting to only last for a few minutes, when it used to last for 20 – a pretty clear sign the battery is about to die. The battery is about 4.5 years old, which is about the rated service life.

Fortunately it is pretty easy to remove.

First flip the ups onto its back, unscrew and remove the panel with the arrow.

Then tilt the ups, and pull on the tab to get the battery out enough to see the power leads on top, they are just blade terminals.

Pull the wires off the terminals and remove the battery. This step is a bit tricky because the wires are very stiff, not long enough to let the battery fully remove, and there is a molded plastic piece in the way. I had to very gently work the wires around to get them out enough to remove.

Inserting the new battery, a CyberPower RB1290 aka B.B. Battery HR9-12, is pretty easy with the same issues with the limited flex of the wires. It takes a bit of bending and force to get them realigned.

After that, snap / screw the base back plate in, plug it in and wait ~8 hours for the new battery to fully charge.

Testing the old battery on my charger shows it still has a good bit of capacity left for low drain applications, and perhaps regenerative discharge of other batteries – hopefully some more about that later.