Battery pack part number starts with “BP” and your UPS model number follows (e.g., BPA11J). You can find which battery pack, and how many you need, at the URL links below.
[ Replacement Battery ]
https://sanups.sanyodenki.us/product_cat/replacement-battery/
[ Battery Locating Chart ]
https://sanups.sanyodenki.us/wp-content/uploads/2018/07/Replacement-Battery-Pack-Chart.pdf
