A few years ago, I pulled an APC Back-UPS XS 1000 out of the trash. Normally, I wouldn’t exactly trust things like this, but after watching enough uxwbill I kinda had the feeling that someone just up and threw it away because the batteries went bad and they didn’t want to invest in new ones. Sure enough, between that and the input sensitivity being adjusted way too high, the unit was completely fine, albeit without any batteries. The alarms can be silenced and the unit can be used as a really beefy surge protector, which is what I did.
This whole piece isn’t to talk about my adventures with the Back-UPS over the years, but rather a cautionary tale: If you plan on pulling the bad batteries from one and just ignoring it/replacing it at a future date, be sure to break down the battery cartridge that comes out of the UPS and salvage the wiring and plastic divider.
In case you’re wondering, it looks like this (though I’m missing one of the wires that goes between the batteries to make it a series circuit):
The reason I say this is for whatever reason, this part is notoriously hard to find. I thought I accidentally threw it away and resigned myself to scrounging eBay, but thankfully my past self tossed it in a drawer and it was safe and sound. (The extra wire I’m not so concerned about. I just need to make my own with some spade connectors and adequate gauge wire.)
As for why I’m also spilling pixels about this: Even with Google it was pretty hard to find an actual diagram of how the thing was supposed to be wired, or what the divider with wiring looked like completely separated from the batteries. Some YouTube videos on the subject showed a seemingly slightly different design with all the wiring built into the divider in a different fashion (which kind of threw me for a loop googling around.)
Now, it isn’t exactly hard to buy fully prebuilt batteries for these UPS units. APC themselves have the full built cartridge for $70, and eBay has third party full built batteries for $60. But if you want to just shove standard 12v cells into your UPS without paying a premium for a built cartridge (and it’s really not hard!) it’s definitely worth it to salvage the wiring and use it to rebuild the cartridge yourself for potentially far cheaper.