I have a small setup with two VMware ESXi hosts connected to Smart UPS 2200 with NMC (SMT2200RMI2UNC). PCNS 4.2 appliance is running on one of the hosts as is vCenter appliance. Shutting down the hosts is working well and they are also starting back up when power returns.
The problem I have is that setting Min Return Runtime on the outlet group doesn't seem to have any effect. Tested with these settings:
Low Battery Duration: 20 minutesOutlet Group 1:Power Off Delay: 720 secondsMin Return Runtime: 840 seconds
When there was 20 minutes of runtime remaining, the outlet group power off delay kicked in and started to bring down the hosts. The host shutdown finished and UPS waited for the rest of the Power Off Delay and after that the Main Outlets group delay for 120 seconds. After this UPS runtime was about 12 minutes according to NMC status page and UPS powered off.
After turning on AC power, UPS didn't wait for the battery to charge but began starting up the hosts almost immediately. Runtime remained in about 11 minutes and when the VMware hosts were starting the UPS logged another "The battery power is too low to support the load" warning. There were some back and forth log messages with "A discharged battery condition no longer exists" and "too low to support the load", maybe because power draw was fluctuating when the hosts were starting up.
I must have a configuration error somewhere? I'm assuming the required power is measured before shutdown events during normal usage and lower load during power off delay shouldn't affect the calculation.
Sorry for the inconvenience. If the load is less than 4.5 amps at the time of shutdown the available runtime will not calculated properly and the UPS will power on when AC is restored immediately as you are seeing. To allow the UPS to charge enough to provide the proper protection add an additional delay. Enter a figure into Power On Delay the allow the batteries to be charged before AC is restored to the outlet group/s.
Another option is to have the load shutdown prior to required runtime of 14 minutes. That way when the UPS restores AC there will be enough runtime to sustain the load.
Thank you, that explains it. I'll add Power On Delay or increase Low Battery Duration to leave more capacity.
How much charge time would it require to add 15 minutes of runtime for around 500-600 W load?
That is tough to say because the charge time is based on the age of the batteries and the environment. I would add a 20 minute delay and adjust after testing.
Thanks, I'll do both earlier shutdown and add some charging time.
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