Well this was an interesting project! It started with the plan to just replace the SLA AGM (Lead-Acid) batteries that were in there BE425M. But, I found out that a seller misrepresented their product (or accidentally shipped the wrong one, but didn't want to admit it), and I had to make a few modifications to make everything work safely. Hopefully makes for an interesting video. Hopefully.

This also might work for other similar APC backup batteries: BE600M1, BE850M2 and BE850G2, along with other APC Back-UPS with similar enclosure profiles.

APC Back-UPS 425 (BE425M) User Manual: https://www.apc.com/us/en/download/do...

Looking for Part 2? Here it is:    • APC Back-UPS 425 (BE425M) Teardown an...