• This procedure can only be done on an APC UPS
• You will need to first know what you APU's battery constant value is.
  For this you will need to locate the white barcode sticker at the rear of your UPS unit and contact RM Support, who will in turn confirm the correct constant value with APC.
• You MUST have the cable with part number 940-0024B, 940-0024C or 940-1524C in order to connect the UPS to a PC. 

 In order to reset the battery constant, we suggest that this is done through a HyperTerminal session.
Please do not enter any other characters via HyperTerminal other than that described in these instructions because this can cause irreparable damage to the UPS.

In order to successfully reset the battery constant, all accompanying devices (SmartSlot Accessories such as Interface Expander, Web/SNMP Management Card) must be removed from the SmartSlot or from the Com port of the UPS.

1. Please shut off all connected load, switch off the UPS, pull the power plug of the UPS.
2. Switch off the UPS once again till you hear a click.
3. Remove all accompanying devices.
4. Turn on the UPS again and connect a computer with Windows 95/98/ME, Windows NT 4.0 or Win 2000, which runs on Hyperterminal using one of the cables mentioned under the requirements.
5. Close Powerchute plus-Server. With Windows NT/2000, the UPS service must be stopped. If you are using PowerChute Business Edition, stop the Agent *V service.
6. Perform a Battery Constants check.
7. Start a Hyperterminal session with the UPS.
   Note: Ensure that there are no accessories plugged into the UPS. (Web Management cards, IO Relay cards etc)
8. Start Hyperterminal by going to Start, Programs, Accessories, Communications, Hyperterminal.
9. You will be requested to enter a name and a symbol. Enter a favourite name and click on OK. When a message that a modem must be installed appears, you can ignore this message.
10. Select the serial port to which black serial cable is connected to.
    The correct settings for the COM-connection are 2400 Baud, 8 data bits, 1 Stop bit, no parity, protocol Xon/Xoff. In this window, click on Advanced and make sure that the option FIFO activated is unchecked. Click twice on OK.
11. Check if there is a connection (Type Shift + Y, should return **SM** )
    Do not enter any other characters via Hyperterminal other than that described in these instructions because this can cause irreparable damage to the UPS
12. Type **1**, wait 2-3 secs and type **1** again (Should return **Prog**) 
13. Enter a **0** and the UPS reports the present value of the battery constant.
    If this value does not correspond to the default value that was given to you by RM Support or APC , it must be changed.
14. If this value is not correct, press **+** or **-** until the correct value is returned.
15. Press **R** to close the session. (Should return **Bye**)
16. Enter **<Shift> Y**, the UPS reports again with **SM**.
17. Enter **0** once again and check if the UPS reports back the standard setting that has been set.
18. Close Hyperterminal, start the UPS again and check the UPS runtime in the management software.

 Warning:  Failure to follow the steps correctly in this article may result irreparable damage to the UPS.