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SMT1500I runtime strangely low ?

Discussion in Smart-UPS & Symmetra LX / RM started by Alain , 8/7/2017 8:40 AM
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  • ALoubert
    New Member New Member
    Alain 8/7/2017 8:40 AM


    I was using for a while a Smart-UPS SUA1500I (aged of ~7 years, with a battery aged of ~3 years that was last calibrated ~1 year ago). Behind this UPS, I have a server and some network devices (router, VDSL modem, switch).
    The total load of those components is around 200W, and with the SUA, I had a runtime of ~55min.

    I now bough a new Smart-UPS SMT1500I (built on the 30/12/2016), and transferred the load by simply moving the cables from the SUA to the SMT.

    After having launched PowerChute Business Edition, I had an apparent runtime of ~65min with the SMT.

    I then launched a calibration.

    => The result: now, only ~28min of forecasted runtime !!!

    I went to look in details at the runtime graph shown in the SMT product page; there, a load of 200W gives ~84min of runtime.

    Strangely, for the SMC1500I, the runtime graph gives a runtime of ~35min...

    My questions are:

    1) Why, for 2 UPS (SMT and SMC) that have the same capacity (1500VA), do we have such a runtime difference (84 against 35min) ???
    The values I measure are closer to the SMC graph, whereas my new UPS is though a SMT... Are you sure the SMT graph is the right one ?
    Though, the SMT graph is closer to what I had with my old SUA...
    What's the issue ? What did I misunderstand ?

    2) Why, before any calibration (ie, in the factory state) did I have 60min of runtime, and after, only the half ? This is a BIG difference !

    3) Why, with my old SUA1500, did I have ~55min of runtime, and now, with exactly the same load, only the half with the new SMT1500 ?

    The SMC is a bit cheeper than the SMT, but I bought a SMT precisely to be sure to keep the same runtime as I had with my SUA, and finally, I have no more runtime than with a SMC !

    Can you give me some clues or explanations, because I really would like to understand what's happening ?

    Thanks in advance.

  • itsm
    Novice Novice
    Phil 8/7/2017 3:06 PM (in response to Alain)

    I have the same issue with my "new" UPS which has 9 month old batteries. 

    With a 150 Watt powerdraw I have 53 minutes runtime. I should have over double. The value also decreased by 40 minutes after performing a runtime calibration. 

    The SMT is supposed to be more efficient and have longer run time, If I had known this was not correct I would have purchased the SMT3000 

  • itsm
    Novice Novice
    Phil 8/7/2017 3:08 PM (in response to Phil)

    sorry should have said I also have the SMT1500RMI2U UPS.

  • liamg
    =S= Representative
    Liam 8/7/2017 8:03 PM (in response to Alain)

    Hi Alain - 

    While the SUA1500i, SMC1500i, and SMT1500i are all 1500 VA units, they have different internal components and capacities. In addition, the SMC1500i uses a much smaller battery. Because of this, you will absolutely see different behavior and runtimes from these units. The VA ratings of the UPS relates to how much load they can support, but not how long it will support it for. If your load is 200watts, you should be seeing ~84 minutes from the SMT1500I and ~35 minutes from the SMC1500I. If you ran a runtime calibration on your SMT1500I and now it only reads 65 minutes with a 200watt load, it sounds like something might be a little off. I would suggest letting it charge for a full 24 hours, and re-running the calibration. Let the unit fully charge after the calibration and you should be closer to that 84 minute mark. Please ensure that the load does not vary more than 5% during the calibration. 

    If you are still having runtime issues after that, you may be having an issue with the battery itself. I would suggest contacting your local tech support team.



  • ALoubert
    New Member New Member
    Alain 8/12/2017 9:17 PM (in response to Liam)

    Hi Liam,

    Well, I followed your advice and let the battery in its state for 72h (still 200W of load with server and network devices connected and powered, but no diags nor calibration on the UPS).
    After 72h, I re-run a calibration, and ...miracle ! I re-get a runtime of ~60min - what I was initially expecting with the SMT, and what I had with my old SUA - instead of the ~30min I had with the first calibrations...

    So, after having started the new SMT, while the battery was showing a 100% charge level (in all cases, I couldn't have been able to launch a calibration if it hadn't been the case), I think it was actually not really 100% full, that's why the calibration showed erroneous results.

    Why did it though show 100% of filling if it wasn't really the case ? I don't know. Perhaps a question of chemical reaction in the battery ?

    So, my advice to all is simple: when you mount a new UPS (or change its battery), running a calibration is still a good thing to do.
    BUT: let the battery under charge for a couple of days in order to have the chemical components stabilize, and run a calibration only after that time, otherwise the results might be hazardous...

    Thanks for your help, Liam.

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