Epson 4SLC2-50 - Manual (Page 52)

4. Press down on the release buttons on the battery compartment
cover and slide the cover toward you.
5. Pull up on the cloth tab and lift out the low battery.
6. Remove the fully charged battery pack from its carrying case
and slide it into the slot. Insert the right side (with contacts)
first, then press on the left side to secure the battery.
Powering the Computer 3-3