How to calculate the battery backup time of a UPS ?

To calculate the battery backup time of a UPS (Uninterruptible Power Supply), you need to know the following information:

1. Battery capacity in Ampere-hours (Ah): This is the total amount of charge the battery can store. It's usually written on the battery or the UPS specification sheet.

2. Load in watts (W): This is the amount of power the UPS is supplying to your devices. It's usually written on the device's label or the UPS specification sheet.

3. Efficiency of the UPS (%): This is the percentage of power that the UPS can deliver to your devices compared to the power it draws from the wall outlet. It's usually written on the UPS specification sheet.

Once you have these three pieces of information, you can use the following formula to calculate the battery backup time of the UPS:

Battery backup time (in hours) = Battery capacity (in Ah) x Efficiency (%) / Load (in watts)

For example, if you have a UPS with a battery capacity of 100 Ah, an efficiency of 90%, and a load of 200 watts, the battery backup time would be:

Battery backup time = 100 Ah x 90% / 200 W = 45 hours

This means that the UPS can supply power to your devices for 45 hours if the power goes out, assuming that the load on the UPS remains constant and the battery is fully charged before the outage.