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SMTL1000RM2UC manual charge | Smart-UPS & Symmetra LX / RM

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SMTL1000RM2UC manual charge

Discussion in Smart-UPS & Symmetra LX / RM started by Andrew , 4/28/2020 4:00 AM
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Posted in: General

SMTL1000RM2UC manual charge

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  • AndrewNCook

    Hi,

    We have a special application where I'd like to manually charge the battery bank of the UPS in addition to the 120V mains rectifier.  Sometimes we use 120V, sometimes a 48V DC charger, so charge rate is always below the cell limits.  I bought a SMTL1000RM2UC, and noted that the SOC calculation looks like it's ONLY counting coulombs, and doesn't pay attention to battery voltage... so a 10% SOC UPS manually charged to 100% with a DC power supply still reads 10%.

    Does APC make a 'dumber' 48VDC UPS that will let me add charge manually?  Lead acid is OK!  But it needs to be 48V.

    Thanks!

  • Brad_C
    On 28/4/2020 12:00 PM, Andrew said:

    noted that the SOC calculation looks like it's ONLY counting coulombs, and doesn't pay attention to battery voltage... s

    That'd be because you can't get anywhere near an accurate assessment of SOC by measuring battery voltage unless the battery has been well rested. You certainly can't get it when its under charge, no matter how gentle the rate.

    All the APC UPS I've looked at use an estimate based on a "coloumb estimate" plus time. They don't actually coloumb count. So you can charge it up externally, and the UPS will gradually increase it's estimate until it matches the actual SOC.

  • AndrewNCook

    If that's the case, it's not creeping up fast enough.  So I'll discharge it through the 110 inverter down to 0%, manually charge the cells at like C/4 to near max voltage, then when I try to run the inverter, it still thinks it's at 0% and won't engage.  So this Smart UPS isn't a good fit for my application. 

    Still wondering if there's a 'dumber' unit I can get off the shelf.

    -Andy

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