How is Runtime Calculated?

[lorenjmiller_apc]

I have a rack supporting VOIP equipment with two "Smart-UPS 5000 RM" units. I replaced all the batteries in both units two days ago. They are at 37% load, and one of the UPSes reported 9 minutes of runtime while the other reported 11 minutes. I replaced the UPS that reported 9 minutes with another UPS that had not been previously in service and moved the new batteries to it. This new UPS with the new batteries that had been reported as offering 9 minutes of runtime now reports 30 minutes of runtime.

The question is how does this work? Is the runtime report accurate, and is there a way to recalibrate runtime on an old UPS with new batteries to get a useful runtime report?

Oh the UPS has the 9617 management card in it. That's how we manage UPSes. We also manage another 230 or so UPSes using an InfraStruXure system, so this is an issue that has come up before with this and other SmartUPS and Symmetra models.

Thanks!
Loren Miller

[BillP]

generally the UPS uses an internal calculation algorithm which is usually more accurate while the UPS is running on battery versus while online. each UPS has a runtime calibration option that discharges the battery to a low percentage and lets it charge back up so that the UPS can recalculate the appropriate runtime. it should be a pretty good estimate.

some of the older units require a more manual calibration that involves a special procedure of putting a 30% load on the unit and letting it discharge until it turns off. the newer units do not require that.

[lorenjmiller_apc]

The birth-date of these units is in 2005. Is that old enough to require the manual process, or should the automatic process work?

[BillP · Accepted solution]

Loren,

If the UPS model starts with an "SU" i.e. SU700NET, it does need the manual process. Our "SUA"'s can perform the software calibration.

Here is an APC Knowledgebase that would guide you on how to perform the manual runtime calibration. It is listed on Option 3

[Why are the battery charge LEDs flashing on a Smart-UPS?|http://nam-en.apc.com/app/answers/detail/a_id/1497/kw/1497]