UPS shutdown on "Low battery" event

[BillP]

I have configured my UPS to shutdown my servers via PCNS when the "Low battery" event occurs on the UPS, meaning only the follwing settings are configured, the rest is left at default:
- UPS: "Low battery duration" set to xx minutes (xx is the time i consider a save threshold for all my servers to shutdown gracefully)
- PCNS clients : "Turn off the UPS after the shutdown finishes" deactivated on ALL servers.
I know that usually one of the PCNS clients should have the option "Turn off the UPS after the shutdown finishes" activated so that the UPS shuts down and "reboots" when the power returns, but i want all my servers to shut down at the same time when the "Low battery" event occurs (because i want to keep them running as long as possible) and i also do not know which server might be the one who takes the longest time to shut down and therefore should be the one with the "Turn off the UPS after the shutdown finishes" activated. It might even vary (depending on the load of the server) which server takes the longest. I therefore do not see the merit of designating one servers as the one who tells the UPS to shut down.

My questions:
- What happens when no PCNS client has the option "Turn off the UPS after the shutdown finishes" activated and a "Low battery" event occurs? Does the UPS shut down anyway (it should, because shouldn't the "Low battery event" trigger a UPS shutdown)?
- If a "Low battery" event does NOT trigger a UPS shutdown, will the UPS simply remain "running" until the battery runs out? What happens when the power returns, does the UPS restart the attached devices or does it remain off because it didn't receive a proper "UPS shutdown" before?

[BillP]

The UPS would shut down when the UPS gets to low battery(default is 2 minutes but it be changed).

What is your current runtime?

[BillP]

The cause may be battery deterioration. The things have lead-acid gel cells that will start to deteriorate after a couple of years, and need to be replaced. It could be that yours are deteriorated enough that they can't hold a charge, and the unit is shutting itself off because it can't supply sufficient charging current.For more information you can refer www.nagaronlinepower.com

Message was edited by: nagaronlinepowers

Message was edited by: nagaronlinepowers

[Anonymous user · Accepted solution]

Hi, i'm am assuming you are utilising the Smart UPS range, or similar? Ideally in order to confirm which server sends the shutdown signal to the unit, you would have to conduct and monitor a "test shutdown exercise" to varify which server is the most appropriate to shutdown last and in turn shutdown the UPS. Realistically though the UPS shutdown signal is only required if you wish to conserve as much battery as possible to optimise battery life, leaving the shutdown setting to defaut and allowing the UPS to drain batteries to it's "dying point" will still eventually cause the UPS to shut down regardless due to exhaustion of stored power (usually at approx 25%). Keep in mind that as your servers shutdown, the load on the UPS lessens, which actually increases your remaining runtime. It's a healthier option for the batteries to have the shutdown signal configured but in your case, due to variable server load/usage you should either deem one specific server as the most appropriate (based on a real time test) or leave the shutdown setting de-activated.

The UPS will always re-start when mains power is restored to site, depending on configuration and/or type of unit it may only restore in bypass mode (not on-line / inverter / load protected) requiring a manual initiation of the inverter.. The unit will always supply power to the load (servers) immediately, either on-line or in bypass.If configured correcly the servers will in turn re-start as desired. Whether the shutdown function is activated or not, it will not impact or alter the operation of any of your other settings. Please be aware, if the unit isn't configured to restart on-line (instead in bypass) and you have a second power outage the servers will immediately lose power. I also suggest that you configure a decent time delay between site power restoration and server restart. This not only varifies continuous supply to site but also avoids repeated startup and shutdown occurences when a power on, off, on, off, on, off situation occurs