Runtime Calibration documentation and explanations

[BillP]

I have a difficult time finding actual documentation on doing battery calibration from APC.  There are lots of opinons and postings, but I can't find an actual piece of APC written documentation on this.  Can someone point me to this if it exists?

Also, I had one of my RT-8000 units lose power and completely run dry.  Given this, is that basically a solid runtime calibration?  Or since it ran dead does that affect this?

I'm getting new batteries for another RT-8000 and its battery packs.  I assume once it's charged up fully I would run a calibration test from the management interface?

If you add a battery pack and forget to add it via the management tools, does the main unit use that battery at all?  Will the extra battery pack still be used if a power outage comes?  Or is it completely ignored as though it doesn't exit until told it is there?

I'm very nervous about doing a runtime calibration with the USP that services our production systems.  Does it supposedly run the batteries down to 20% and then kick back on?  How does this work?

[BillP · Accepted solution]

I will have to see about the best place for a software calibration as far as documentation but here is an outline on a manual runtime calibration below. There is also the way via the Network Management Card or PowerChute to issue a calibration which I'd call a software calibration or issued by the software.

This is a manual procedure and should not be confused with the runtime calibration performed through PowerChute software. The batteries inside of the Smart-UPS are controlled by a microprocessor within the UPS. Sometimes it is necessary to reset this microprocessor, especially after the installation of new batteries. Note: Before beginning the calibration make sure the UPS has been online and charging for at leat 24 hours for just the UPS or 48 hours for a UPS with external batteries. Stop the PowerChute software from running and disconnect the serial cable. There must be at least a 30% load attached to the UPS during this procedure, and this load cannot fluctuate more than +/- 5%. This process will cause the UPS to shut off and cut power to its outlets, therefore, attach a non-critical load to the UPS and then force the UPS on battery by disconnecting it from utility power. Allow the unit to run on battery until it turns off completely. Make sure a 30% load or greater is present! Plug the UPS back into the wall outlet and allow it to recharge (it will recharge more quickly turned off and with no load present). Once the unit has recharged, the "runtime remaining" calculation should be more accurate. Remember that if the unit is an older model, then the runtime will not improve significantly. Note: Should the previous steps not resolve the issue contact APC support at 800.890.4272 for further assistance.

Since the runtime calculation is a really good estimate while running online, putting it on battery and letting it discharge and charge back up allows it to calculate. You'd only do this 1-2 times a year at the max and after new batteries if your runtime doesn't update. It really depends on the UPS how well this calculation works if you ask me since across the different product lines, the calculation may be slightly different.

If you have frequent discharges on a UPS, yes, I think that this is ultimately a calibration and I would not waste a discharge on the batteries to do a calibration since ultimately it calibrates each time it discharges. If you don't think you meet the conditions above load and load fluctuation wise, then maybe consider a calibration. I personally would really only worry about calibrating if your runtime estimate is completely crazy. With frequent outages, it will eventually calibrate itself when it is put on battery.

The calibration is just updating the battery runtime reported and if you don't have a problem with what's reported, no need for a calibration. If you choose to do one yes, the UPS needs to be online, at 100% charge, and I'd make sure you have at least 30% load on there and make sure it does not fluctuate to make sure this procedure is worthwhile, as noted with the manual calibration instructions.

If you do one, yes, it discharges the UPS down to between 10-20% depending on the model. Only if your batteries were complete "toast" and not new would I be worried of the slim change that the UPS goes to battery and cannot support the load at all and it turns off. So, it just operates on battery (does not signal any PowerChute client shutdowns) and then goes back online and charges back up.

If you add a battery pack physically but forget to add it in the software, this only affects the battery runtime reported and nothing else. The batteries are still part of the DC bus and both the internal UPS batteries and external battery packs will still be utilized.