Considerations for Smart UPS 5000VA uptime?

[Anonymous user]

Hi, Our building power (including backup power) will be cut to repair our generator. This will mean a 60-90 minute outage, followed by 5 hours uptime, followed by another 60-90 minute outage.  We need to keep one server online during this outage which is estimated to use 650Watts in worst case scenario. Our reading of the APC documentation indicates that a Smart UPS 5000VA can supply 650Watt units for 100 minutes. The 5000VAs appear to be in good working condition. 

1) Should we have confidence in the 100 minutes estimate from the documentation?

2) Will 5 hours be enough time for UPS recharge?

3) Are there other considerations?

Thanks

[BillP]

Hi Edward - 

Do you know which 5000VA unit you have? There should be a small white sticker under the front cover with a model and serial number. Do you know how old the batteries are? Are there any external battery packs connected?

The numbers provided online are estimates and assume a new battery. Depending on the battery age, load, and environment, your real world performance may vary. Every Smart-UPS 5Kva and larger ships with a network management card. If you log in to the NMC's web interface you will see an estimate of your current runtime. Prior to your expected outage, you may want to run a battery calibration to make sure the runtime being reported is as accurate as possible.  (This is also initiated from the NMC).

5 hours will likely not be enough time to recharge the batteries fully, but should get you to 80-90%, which might be sufficient.

Liam

[Anonymous user]

Hi Liam,

Thanks for the reply.  The numbers I see are SUA5000RMT5U and JS0847012055. There are no external battery packs, but the unit has four built in.  We do not have the web interface connected, but via serial cable we see that with the single 650Watt system attached (with no bars of load) it says there are 95 minutes of backup time, while if add servers to bring the load to 2 bars, it says there are 21 minutes of backup time.

We have not run the battery calibration, because we have seen online that some folks reported the APC unit shutting down during calibration and attached servers go offline. I assume this is not normal behavior, but we don't want to risk bringing down the single critical server attached.

Without battery calibration, can we have any confidence to the 95 minute and 21 minute backup times we find?

Thanks, Ed

[BillP · Accepted solution]

The real question would be how old are the internal batteries and when was the last calibration done. The load is also very small given the size of the UPS, which makes it harder for the UPS to accurately predict runtime. Typically you need at least 20% load for the runtime numbers to be accurate. That UPS is 10 years old, so you should be on your 3rd or 4th set of batteries by this point. 10 years is a pretty typical lifespan for the UPS, so its hard to say if everything as working as well as when it was new. 

Sorry I don't have more clearcut answers for you. 

Liam