A PC consuming 100 Watts is to be operated on a UPS. The UPS uses a 12 Volts, 100 AH battery. Assuming unity PF, what is the backup time of this unit?

A PC consuming 100 Watts is to be operated on a UPS. The UPS uses a 12 Volts, 100 AH battery. Assuming unity PF, what is the backup time of this unit? Correct Answer 12 hours

Concept:

The capacity of the battery is represented in terms of Amp-hour.

The capacity of battery = current delivered × backup time

Power consumption is given by

P = V I cos ϕ

Where,

V = Voltage

 I = Current delivered

cos ϕ = Power factor

Calculation: 

Given that, V = 12 volts, cos ϕ = 1, P = 100 W

capacity of battery = 100 AH

∴ I = 100 / 12

Now backup time can be calculated as

Backup time = 100 / (100 /12)

Backup time = 100 hours