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Very low runtime on low load UPS compared to similar model with high load

Discussion in Smart-UPS & Symmetra LX / RM started by Pieter , 10/12/2016 1:04 AM
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  • ptr727
    Pieter
    Novice Novice
    Pieter 10/12/2016 1:04 AM

    Hi, I have two similar model, one slightly newer than the other Smart-UPS 750's, with NMC2 cards.

    This morning we had a short power failure, and one UPS lasted less than 6 minutes, the other the entire outage.

    Weird thing is the UPS that ran out of power has much less load..

    This is from the two UPS's:

    Battery Temperature
    33.7°C
    Runtime Remaining
    5min
    UPS Input
    Input Voltage
    114.4 VAC @ 60.0 Hz
    UPS Output
    Output Voltage
    114.4 VAC @ 60.0 Hz
    Load Current
    0.7 Amps
    Output VA
    9.7 %
    Output Watts
    7.8 %
    Output Efficiency
    79.0 %
    Output Energy Usage
    2081.38 kWh
    Battery Status
    State of Charge
    100.0 %
    Battery Voltage
    27.0 VDC
    Next Battery Replacement Date
    06/24/2021

    Battery Temperature
    32.8°C
    Runtime Remaining
    28min
    UPS Input
    Input Voltage
    113.0 VAC @ 60.0 Hz
    UPS Output
    Output Voltage
    113.0 VAC @ 60.0 Hz
    Load Current
    1.8 Amps
    Output VA
    27.9 %
    Output Watts
    37.0 %
    Output Efficiency
    95.0 %
    Output Energy Usage
    3629.90 kWh
    Battery Status
    State of Charge
    100.0 %
    Battery Voltage
    27.1 VDC
    Next Battery Replacement Date
    04/04/2043

    Notice the 28mins vs 5mins runtime, and yes I see the efficiency is 95% vs. 79%, but the load is 1.7A vs. only 0.7A.

    How is it possible that the 1.7A draw will last 5 times longer than the 0.7A draw?

    The UPS's are scheduled to self-test every two weeks, no errors reported.

    I ran a manual self-test on the bad UPS, and the test passed, but the battery failed.

    How is it possible for the test to pass but clearly the battery failed?

    10/11/2016 18:07:06 Device UPS: A low battery condition no longer exists.
    10/11/2016 18:07:06 Device UPS: The battery power is too low to support the load; if power fails, the UPS will be shut down immediately.
    10/11/2016 18:07:05 Device UPS: Self-Test passed.
    10/11/2016 18:06:59 Device UPS: A discharged battery condition no longer exists.
    10/11/2016 18:06:59 Device UPS: The battery power is too low to continue to support the load; the UPS will shut down if input power does not return to normal soon.
    10/11/2016 18:06:58 Device UPS: Self-Test started by management device.
    10/11/2016 18:06:56 Device UPS: The battery power is too low to support the load; if power fails, the UPS will be shut down immediately.

    Bad battery?

  • ptr727
    Pieter
    Novice Novice
    Pieter 10/22/2016 4:05 PM (in response to Pieter)

    I replaced the battery, and runtime is back to normal.

    Seems to me that the battery test is not doing its job.

    APC, how about it, logs clearly shows dead battery during test, but battery test passes?

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