Last friday I've done a calibration of a brand new SUA750XL with one SUA24XLBP attached. I used a 150 watts lamp as the only load and unplugged the UPS from the wall. The power from the batteries lasted for 8 hours 34 minutes. That's a bit longer than what can be estimated from the APC website.
Now, with the normal load attached (one 24 ports switch, 3 routers, 2 modems, 1 WIFI access point) PowerChute indicate a load of 0.8A. That's about 100 watts. PowerChute also estimate that the UPS can make this run on batteries for only 488 minutes or 7 hours 8 minutes. This seems wrong to us. The UPS powered a 150 watts lamp for 8.5 hours and is now estimating just over 7 hours for a 100 watts load.
Can there be something wrong with PowerChute estimations (by the way we declared 1 battery pack in PowerChute for our SUA24XLBP. Is this Ok?) or can there be something wrong with the calibration process.
The External Battery Pack count which you have set is correct. The SUA750XL + (1)SUA24XLBP estimated run time is 9 hrs 45 mins if the equipment connected consumes 100 Watts of Power from the UPS outlets. Click on the below link to view the SUA750XL runtime chart:
I would like to gather some more information from you to understand what is going on with the unit. Could you please let me know the Power Chute version which you are using to monitor the UPS? What was the battery capacity when it showed 7 hours 8 minutes of run time? If possible, could you please post the data and event logs of the UPS on this thread?
it should also be noted that while the UPS is online and running off of AC power, the estimated runtime is an estimate. the value should become more accurate while its running on battery and after a couple of discharges, should update accordingly. when the UPS is very new, sometimes you can see a difference in reported runtime versus actual runtime.
as you could see, the batteries worked just fine and lasted as they should when you discharged the battery. i would not waste another discharge by doing a manual calibration based on the fact that you know the batteries lasted the correct amount of time on your first discharge.
i would suggest keeping an eye on the runtime reported through the powerchute software, knowing its just an estimate, and then make sure it evens out over time with the observed runtime during your initial discharge.
Thanks you both for your help. Since I at least know that the batteries are working correctly and near the APC's estimation, i'll live with the uncertainty of the estimation and not do another discharge.