Configuring APC UPS based on minutes.

Anonymous user · ‎2021-07-01

Hi All,

I have configured APC UPS based on minutes left. I noted that the minutes left does not steadily decrease. For example, I have configure my system to auto shut down when battery charge reaches 30 minutes remaining. Now say the power goes off. The battery discharge is inconsistent. From 100 minutes, it jumps to say 93 minutes and then to 98 minutes and then 85 minutes and so on. I get this data by looking at TIMELEFT parameter of apcaccess command. Do I need to configure something so that the UPS discharges consistently?

BillP · ‎2021-07-01

Unfortunately, batteries don't typically discharge at the same consistent rate, especially as they get older. This is why our software typically shuts down based on time ON battery rather than runtime left, as time ON battery is a constant and runtime remaining is not. What type of software are you using to do this?

See Answer In Context

voidstar_apc · ‎2021-07-01

Well, we do encourage using time left on battery because batteries provide less runtime as they age. Using "time left" avoids the problem of not having enough runtime to finish a shutdown.

But yeah, time left is just an estimate. The UPS is constantly re-estimating based on its measurement of the battery, so the estimate may go up and down. That's okay so long as the estimate is accurate or even pessimistic.

BillP · ‎2021-07-01

Unfortunately, batteries don't typically discharge at the same consistent rate, especially as they get older. This is why our software typically shuts down based on time ON battery rather than runtime left, as time ON battery is a constant and runtime remaining is not. What type of software are you using to do this?