XS 900 - Incorrectly Reporting Battery

[Anonymous user]

I've been using an XS 900 for a while and it's worked pretty well. However, in recent months I've added too much to it and didn't watch my wattage, effectively overrunning its on-battery output. Combine this with having accidentally left the battery connected while everything was unplugged during a week-long vacation, and the battery was thoroughly drained.

So I bought a replacement battery from APC and also bought a second UPS (BX1500G, very happy with it) to handle the additional load. The new unit is running fine, but I'm continuing to have an issue with the old unit and its new battery. It seems to be incorrectly reporting the uptime.

The only thing plugged into it at this point is a low-power (80 watts) Linux box running the latest apcupsd package. When I check the status through that software, the UPS claims a few seemingly incorrect things:

1) 19% Load Capacity - For a single 80W (max) device? The effective output is listed as 540W. But I could be fine with that as maybe a rounding error here or there, no big deal.
2) 0.7 Minutes Time Left - It's a new battery and has been plugged in for a few days. It should be effectively charged. Why would there be no time left? It says 100% charge, but the time is way too low.

When I unplug the UPS, the software sees that the remaining time is below the set threshold and shuts down the computer. However, if I remove the data cable to cut communications, the battery successfully runs the computer just fine for well over an hour (as expected).

So it seems the UPS' controller is a bit confused. Does anybody have any suggestions on how to address this? I'd like to keep the data cable plugged in so the computer can be properly shut down, but not until 20 minutes has passed. If anybody has any suggestions I'd really appreciate it. Thank you.

[BillP · Accepted solution]

hi,

i think as you have proven here with removing the data cable, the UPS calculation is messed up and is not reporting the proper runtime but the battery itself provides the time it should.

i would recommend a calibration which will do a full discharge of the UPS until it turns off. so, to do that, i would ensure the unit is 100% charged. when it is, remove the data cable. plug a non critical load in or the same load you had, (maybe a bit more to speed this up) and let the UPS run on battery until it FULLY discharges and turns off. THEN, reconnect it to AC power WITHOUT the data cable attached with the unit turned OFF but connected the wall so that it can charge. i would let it charge overnight if you can, just to ensure a full charge. i also recommend leaving it off but still plugged into the wall to charge because this will ensure that if you have a power outage or something, the UPS will not kick over to battery and ruin the calibration. once everything is charged up, then i'd reconnect the data cable and see what you get.

hope that helps!