are you sure it's a LI-Ion battery and not a SLA (sealed lead acid) battery pack?
almost every UPS i have seen uses SLA and not Li-Ion batteries as this technology is quite new to UPS'S
hmmmm it appears that the ups model you have is Li-Ion in the 1U form factor and SLA in the 3U form factor
https://h20195.www2.hpe.com/V2/GetPDF.aspx/c04376695.pdf
last, this is a HP Enterprise product and not a HP Inc product so you are on the wrong companies forum you need to go here:
https://www.hpe.com/us/en/home.html