CyberPower BAS34U24V Automation System UPS, 14.8V/6500mAh Li-Polymer Rechargeable Battery, 3 Outlets, TS35 DIN Mount

Cyberpower won't sell a replacement battery or give you a part number, or help you find one. You will need to make your own. Hopefully you're comfortable playing with Li-Po because that's what's required to keep these operational. If Cyber power would even so much as provide their own supplier or some specific data on the battery cells or a how-to document to manufacture your own replacement battery pack then I would go from 1 star to 5.

I purchased three of these and they just don't work. Even with as little as 7% load the UPS function doesn't work. You can have a full battery and the UPS won't activate when power is lost. Also some devices just set off the overload protection even though they only pull .09 amps. Save money and time, buy something else.

I bought this UPS for some remote Mikrotik network equipment. But while it works for my tightly specked use case, it really doesn't have enough power even for a basic modem. It's really more designed for PLCs and other "low power" industrial equipment where you want remote supervision of the UPS too (via SNMP reporting).The main output is only 25W @ 24VDC. So there are considerable constraints to consider if it's right for your application.