73
017-220-J0 Rev C
10. Peukert Number
10.1 Introduction
The Alpha Micro 100 UPS units run on batteries when the AC utility power fails. In this mode, the user may want to
estimate the remaining time that UPS batteries can supply power to the loads.
The battery run time remaining is calculated based on the Peukert equation.
The Peukert number depends on the battery characteristics. This document describes the procedure to determine
the Peukert number for the selected battery.
Once the Peukert number is determined, enter these values in the GUI or web interface. The Alpha Micro 100 will
report the remaining battery run time.
The Peukert equation and the remaining battery run time are estimates only. The actual run time may vary based on
various parameters like the age and status of the batteries etc.
10.2 Determining the Peukert Number
1. Obtain the data sheet of the selected battery.
2. Calculate the nominal load current for the application.
Example: If the load is 85 W and the battery string is 24Vdc, the load current is calculated as 85W / 24V =
3.54A.
3. Find the current discharge ratings table in the data sheet. From the table, pick two current discharge values (I1
and I2) that are closest to the calculated load current and look up the two discharge hours (R1 and R2).
4. Use the following formula to calculate the Peukert number:
Peukert’s number = n =
Log (R
2
/R
1
)
(Log (I
1
) - Log (I
2
))
Summary of Contents for Alpha Micro 100
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