Runtime issue with new battery for Back-UPS Pro 420

[Anonymous user]

Hello,

I just recently replaced the battery in a Back-UPS Pro 420 with a new RBC2 APC battery. Let the battery fully charge then ran a UPS Calibration test through the Powerchute BE SW. It said it completed the test and the battery capacity went down to about 25%. I then let it fully recharge(about 5 hours) to 100% and it no longer says its discharged but the runtime is only at 4 mins and it complains about insufficient runtime. The load on the UPS this whole time is only at 38-39%. Do I have a faulty UPS here or is the runtime calibration not working correctly?

Thanks.

[Anonymous user]

Also, what exactly does the runtime calibration do? Run the UPS off battery power for as long as the estimated runtime and see if it shuts down or not?

[BillP]

a runtime calibration discharges the battery down to a low percentage, like you saw, and then charges it back up so the UPS knows how much time it took to discharge and at what rate so it can keep an accurate tally of the runtime after doing some internal calculations. sometimes this doesnt work, like you saw.

what you can try is doing a command via a terminal program and the serial port to try to manually update this value.

theres two different things you can try. 1.) do a manual runtime calibration where you basically put a minimum of 30% load on the UPS and let it discharge down to 0% till the UPS turns off, then let it charge back up again and see what it says or 2.) we can try changing the battery constant via the serial port but i am not sure if that unit you have allows that. i'd have to check into that.

let me know if you're interested in doing that or if you want to try the manual runtime calibrations. if that doesnt work we will see what else we come up with because the more complete discharges on the battery, the shorter the life. so we dont want to do this 10 times in a row.

[Anonymous user]

Well doing the manual discharge is a little difficult because I am supporting the UPS system remotely, could the method of changing the battery constant be done remotely?

Also, when does the battery stop being dischaged? Does it have to be at 100% to be normal? Because even though the battery is at 100% and powerchute says its normal I still get alarm emails saying the battery is discharged.

[BillP · Accepted solution]

well the UPS is at 100% charge but its calculating the runtime incorrectly which in turn reports "battery discharged" cause your runtime is low. so we need to help the UPS fix its runtime calculation which will get rid of the messages.

we would need the serial cable attached and stop the powerchute service from running, then to use hyperterminal or another terminal program to issue some commands to the UPS. its worth a try, i am not 100% sure if it will work to be honest but its all we can do.