knowing about Switched mode power supply

[Disha Karnataki]

i have a SMPS :
the ratings are:
250VA capacity.
230vac i/p .
battery i/p 12V.
now how do i decide battery AH?
say i want to use 20W 4 CFL tubes for backup time of 1 hour.

 

[barry]

Are you confusing an Uninterruptble Power Supply with a SMPS?

Well, by GUESSING at what you are really asking: you need 80 watt-hours. 80/12=6.6 AH. This assumes 100% efficiency.

 

[Disha Karnataki]

80/12=6.6 AH. This assumes 100% efficiency.

charging current is not mentioned on the UPS so i do not know whether 6.6Ah will suit that charging current .