APC UPS Recalibration

After replacing the batteries in an APC UPS, you may find that the UPS still indicates that the batteries need replacing; the solution is to carry out a run-time recalibration - here's how.

The problem here is when your UPS still indicates that the batteries neeed replacing even after you have fitted brand new batteries. From experience this happens if the UPS has not been used for a long time or if the previous batteries were particularly old or in poor condition.

The best way to carry out a run-time recalibation is by using the Network Management Card (if installed) and/or APC's PowerChute UPS Management Software, which is available as a free download from the APC website.

For newer Smart-UPS "SUA" and "SM" models these are the only ways that the unit can be recalibrated; older Smart-UPS "SU" models can also be manually recalibrated using the following procedure:

1. Fully charge the UPS battery by connecting to a mains supply for at least 24 hours (48 hours for installations with additional external batteries)
2. Shut down any UPS monitoring/shutdown software that is in use
3. Disconnect any serial cable connections to the UPS
4. Disconnect the mains supply and apply a stable load to the UPS of at least 30% of its rated output until the battery is fully discharged and the UPS shuts down
5. The load must not vary by more than 5% during this procedure
6. Re-charge the UPS battery by connecting to a mains supply for a further 24 hours (48 hours for installations with additional external batteries)
7. Reconnect any serial cable connections to the UPS
8. Restart any UPS monitoring/shutdown software that is in use

The UPS run-time recalibration is now complete

If you still have any queries about recalibrating your UPS please call us on 01992 707030