How To: Swap RB63 UPS Batteries in an APC S20 BLK

This post is primarily a how-to for my own benefit, since I own a total of five APC S20 BLK battery backup units running a variety of things at the house from AV gear to a rack of servers. That means there’s a chance I’ll need to replace the battery pack in any one of these units at any given time, but not often enough to remember exactly how they connect internally without a bit of visual help. 🙂

My earlier posts aimed at saving money on UPS batteries (this one explaining how, and this one giving specific batteries to use) are worthwhile reads if you’ve landed on this page as a result of a search. The MSRP of an RB63 battery pack is $173. The Amazon street price is about $160. But a pack of four UB1920 batteries can be purchased for less than half of that (my most recent purchase was $76 shipped on eBay), and used to rebuild the original battery pack better than new. I say “better,” since the original batteries are 12V 7Ah units, while the UB1920 ones I buy are 9Ah units — meaning they’ll provide a longer on-battery runtime.

Following is a quick visual explanation of how to remove the old RB63 battery pack from an APC S20BLK, swap out the internal batteries with generic replacements, and put the whole thing back together. Also, it’s possible to do this as a “hot swap” — meaning you don’t have to power down the unit to replace the battery pack. Just pray that the power doesn’t go out while you have the battery pack removed!