Resetting the UPS Battery Constant

Note: after resetting constant, let the UPS take time to increase battery capacity indicator (led on front panel and % on apcupsd monitor).

Taken from http://www.apcupsd.com/manual/manual.html#resetting-the-ups-battery-constant

Resetting the UPS Battery Constant

In some cases none of the battery runtime calibration methods result in the UPS reporting a reasonably correct battery runtime. It has been speculated that this is because the battery constant value has drifted so far from normal that the microprocessor in the UPS cannot correct it.

The good news is that if you are located in the USA, all you have to do is contact APC Technical Support and they will send you a serial port dongle which plugs into the serial port of your UPS and reprograms the battery constant value for you to the correct value.

The bad news is that for many users outside the USA, this service does not appear to be available. It is, however, recommended that you first try contacting APC Technical Support to verify the correct battery constant value. The APC representatives in the Support Forum on the APC website are also very helpful in this regard.

If all else fails, the information below is for you.

WARNING: Only the values for the Smart-UPS 700 model SU700 and Smart-UPS 1400 model SU1400, both with international firmware (and therefore international voltage), have been verified. YOU, gentle reader, USE THIS INFORMATION AT YOUR OWN RISK in the full knowledge that you may render your UPS inoperable and perhaps irreparable, and you will have no-one to blame but yourself. Caveat Utilitor!

The battery constant is the hex number in the column labelled "0", presumably for register 0, in the following table:

UPS Model         4  5  6  0    Hex   Firmware
SU250               EE F8 B1
SU400               EE F8 9F    E1
SU600               EA F4 9F    E5
SU900               F3 FC 9F    ED
SU1250              EE FA 9F    F5
SU2000              F1 F9 9F    FD
SU450,700        28 F2 FA 96 07,RM=47  52.11.I
SU450XL,700XL    28 EE F8 9F 700XL=27   51.9.I
SU1000,INET      35 EF F9 A0    0B     60.11.I
SU1000XL         34 EE FC 9A    2B      61.9.I
SU1400           35 EE FC 9A           70.11.I
SU1400RM         28 ED FA 89
SU1400R2IBX135   08 B4 10 A3
SU1400RMXLI3U    45 F6 F4 80            73.x.I
SU1400RMXLI3U    20 F3 FD 81            73.x.I
SU2200I          35 EE FB AF           90.14.I
SU2200XL,3000    35 EE FB AF 3000=17   90.14.I
SU3000RMXLI3Ublk 35 F3 F4 AF    77     93.14.I
SU5000I white    20 F2 FA 91    1F    110.14.I
SU1400XL,XLI,RM  45 F6 E4 80
SU420I           25 95 09 85    16      21.7.I
SU420SI          0E 95 0A 8C
SU620I           29 99 0B 8A    1A
BP420SI          0E 95 0A 8C    06      11.2.I
BP650SI          10 97 0C 91    0A      12.3.I
Power Stack 250  0C 95 0F B2            26.5.I
Power Stack 450  0D 96 10 99    36      26.5.I
SC250RMI1U       0C 95 0F B3    32     735.a.1
SC420I           0E 95 OA 8C    16     725.1.I
SC620I           10 97 OB 99    1A     726.x.I
SC1000I          08 95 10 94    8A     737.x.I
SC1500I          07 95 14 8F    1E     738.x.I
SU1000XL         17 EE F9 D5
MATRIX 3000,5000    E9 F5 B0
SU700RMI2U       07 B1 0D 92    8A     152.4.I
SU1000RMI2U      08 B5 0D C7    8E     157.3.I
SU1400RMI2U      08 B4 10 A3    92     162.3.I
SUA1000I         07 B5 13 BC    0A    652.12.I
SUA1000XLI       0B BD 0F 7F    4A    681.13.I
SUA750XLI        0A B9 0C 86    46     630.3.I
SUA750I          04 B6 14 82    06    651.12.I
SUA750RMI2U      07 B1 0D 82    86    619.12.I
SUA1500I         09 B9 13 A1    0E 601/653.x.I
SUA1500RMI2U     08 B4 10 A1    8E     617.3.I
SUA2200I         08 B8 12 B3    26    654.12.I
SUA2200RMI2U     09 BC 11 81    A6     665.4.I
SUA2200XLI       0A B7 0F 7F    66     690.x.I
SUA3000RMI2U     04 B9 0E 70    AA     666.4.I
SUA3000RMXLI3U   0A B6 0E 89    xx     xxx.x.x
SUOL1000I        06 B6 1B A6
SUOL2000XL       0D BD 14 75    52     416.5.I
SURT1000XLI      0A BB 19 A8    4E     411.x.I
SURT3000XLI      06 B6 0F CC    56     450.2.I
SURT5000XLI      05 BA 15 86    5A    451.13.W
SURT7500XLI      03 BB 20 97    63
SURT10000XLI     06 B8 19 AB          476.12.W
SUM1500RMXLI2U   03 B7 0D A5    62     716.3.I
SUM3000RMXLI2U   03 B7 0D A5    6A     715.3.I
BP500AVR                        26      17.1.I

The instructions for resetting the battery constant are as follows:

Shutdown the apcupsd daemon;
Run apctest;
Choose option 6 to enter terminal mode;
Enter Y (UPS should respond SM);
Enter 1 (one, not el; wait 4 seconds);
Enter 1 (one, not el; UPS should respond PROG);
Enter 0 (zero, not oh; UPS should respond with current constant);
Write down the existing value so that if something goes wrong, you can at least put it back to that value;
Enter + (plus) or - (minus) to increment/decrement the value;
Enter R to reprogram constant value (UPS should respond Bye);
Enter Y (UPS should respond SM);
Enter 0 (zero, not oh; UPS should respond with the new constant);
Enter Esc to exit terminal mode;
Choose option 7 to exit apctest.

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