UPS Autonomy - How to calculate it?

Calculate the autonomy (backup time) that the UPS can give you depending on the load

UPS Autonomy - How to calculate it?

One of the most important factors for choosing the right UPS is the time of autonomy that we want the UPS to give us in case of failure. The type and number of batteries the UPS has determines its autonomy.

The calculation can be done with the following formula:

C = (P × T) ÷ (V × η × K)


  • C - Battery capacity, in Amps × hour (Ah)
  • P - Load power in Watt (W)
  • T - Autonomy time; in hours (h)
  • V - Rated battery voltage, in Volts (V)
  • h - Battery converter performance
  • K - Battery discharge factor

    1. Όταν ο χρόνος αυτονομίας της μπαταρίας είναι <3h, K = 0.6
    2. When the battery autonomy time is 3~5h, K = 0.8
    3. When the battery autonomy time is 5~10h, K = 0.85
    4. When the battery autonomy time is >10h, K =1

For example, if the load is 8000W and the required autonomy time is 1 hour, then the batteries that can be used in a UPS should have the following characteristics.

C = (8000W 1 )/(12V 16 0 .92 0.6) = 75.5AH.

So a 100AH battery can guarantee about 1 hour of autonomy.

Tescom Hellas has batteries that can cover all types of UPS. Learn more here.

In case you need help with the calculation of the autonomy or you have questions, you can contact the experts of Tescom Hellas to help you.