Question UPS runtime calculator

[noob25002]

Hello,

How can run time be estimated for an UPS?
For example with a Cyber Power BU650E which has one 5 Ah / 12 V battery, with a stable power consumption device?
Cyberpower says 30 min @60W and 18 min @90W.
But my new unit only does 14 min @63W and 40m @27W, measured with a wattmeter.
By itself the ups it draws ~10W.

It's new, so if it is the battery that's lost some of it's capacity it must have sat in a warehouse or inappropriate temperature?

 

[Red Squirrel]

The times they advertise are always super optimistic. Most off the shelf UPSes are only really good to give you a chance to ride a small outages that lasts a few minutes and then start shutting down if the power does not come back.

Basically if the substation recloser does not manage to bring power back within a few minutes or the fault is a local one where a fuse blew on a line, chances are the power will be out for an hour anyway as they need to send linemen out.

Gel cells also degrade pretty quickly, they are a terrible type of battery. Flooded acid tends to last much longer if cared for but they do require maintenance which is why small desktop UPSes don't use them. If you do want long runtime though then consider an inverter-charger and a bank of big flooded batteries. I have a setup like that for my servers and I'm good for a few hours.

 

[mindless1]

Could be false specs, or compromised battery, but in *theory* the numbers Cyberpower spec's, aren't far from achievable from a 5Ah battery in good condition, full charge state.

So I'd try a new battery or use a DC clamp meter to measure current draw from the battery, then calculate out how much of that 5Ah is available before the UPS shuts down. Certainly it will be below 5Ah just due to drawing such a large load off of it, making it dubious that they state an "650" UPS, which I assume means 650VA, runs off a little 5Ah battery.

In other words I would pick an ups with a larger battery or pair of two 12V batteries for long runtime, or rig something yourself to connect a larger battery to that UPS, IF the charging circuit doesn't have a problem with it, and IF the UPS doesn't overheat from the extended running time.