UPS Battery Run Time

[zaheer708]

I need some calculation on based of following findings:

UPS rating = 1200 Watt

Battery Rating = 1300 Ah

Total Connected Load = 1000VA

Operating Voltage = 240 V

Can anyone please calculate for how long battery will provide power to the load ( i mean run time) ?

Please show full calculation.

Thanks a lot.

 

[malcolmsanford]

That would be very hard to calculate without the battery specs. As soon as the system energises the battery should be at a peak 95%, it will never be 100% due to many things climate, type of battery, age of battery etc etc

Once the systems is working that battery or pack is draining, and so depending on again those factors and the specs of the battery the drain time will vary as it will be a graph and so it could be as long as a piece of string.

Many mix up UPS as a total back up system which it is not. It is normally installed just to take an installation from mains supply over to a generation system to restore emergency power, and then off of generation back to main supply.

If there is no back up generation then the UPS will not run a system for very long maximum of perhaps 10-15 minutes in order for whatever work is being done to be saved, as in IT applications and allow for safe shut down, normally signaled by the UPS itself when the batteries reach a critical stage of drain

 

[zaheer708]

That would be very hard to calculate without the battery specs. As soon as the system energises the battery should be at a peak 95%, it will never be 100% due to many things climate, type of battery, age of battery etc etc

Once the systems is working that battery or pack is draining, and so depending on again those factors and the specs of the battery the drain time will vary as it will be a graph and so it could be as long as a piece of string.

Many mix up UPS as a total back up system which it is not. It is normally installed just to take an installation from mains supply over to a generation system to restore emergency power, and then off of generation back to main supply.

If there is no back up generation then the UPS will not run a system for very long maximum of perhaps 10-15 minutes in order for whatever work is being done to be saved, as in IT applications and allow for safe shut down, normally signaled by the UPS itself when the batteries reach a critical stage of drain

My scenario is little bit different. There are unscheduled power break downs in my area which prolong upto 10 hours ( in extreme cases). Some of my friends have installed UPS systems (with same specs as in my question) which supply power up to 5 hours at a stretch. I just need the calculation for those UPS on which they perform.
Thanks

 

[zaheer708]

Actually, Brother, I need you to show some calculation on any assumption from your own. In layman's terms, you can assume that i need to switch on 3 ceiling fans, 3 tube lights and a computer (monitor+ CPU) which gives you around 1000 VA as total load.

Now you can assume that you have 1200 W UPS and Two Lead Acid batteries each 1300 Ah. Considering Ideal conditions, how will you calculate the run time?

Lead acid batteries operate on 12 V. How can you turn on a light with 12 V which actually works at 240V?

Please give explanation in LAYMAN'S TERMS. Thank you.

 

[Golden_Boy]

"Two Lead Acid batteries each 1300 Ah."

Thats two VERY big batteries? With 12 volt batteries and a drain of 1000watts the current would be 83 amps. so allowing 75% efficiency for your UPS lets call it 100 Amps. So 2600 AMP HOURS with a drain of 100 amps would be 26 hours.( I think my sums are right )
So allowing for battery efficiency I would imagine 10 hours ?????

 

[Octopus]

Try using this ....

UPS Selector Sizing Applications

 

[zaheer708]

"Two Lead Acid batteries each 1300 Ah."

Thats two VERY big batteries? With 12 volt batteries and a drain of 1000watts the current would be 83 amps. so allowing 75% efficiency for your UPS lets call it 100 Amps. So 2600 AMP HOURS with a drain of 100 amps would be 26 hours.( I think my sums are right )
So allowing for battery efficiency I would imagine 10 hours ?????

I'm very sorry. Battery rating is 130Ah not 1300Ah. Human error.

Now can a 12V battery turn on a 240V-Light or fan?????

If total load is 1000 Watts or 1000/0.8 = 1250 VA and voltage is 240V. Then your current is 1250/240 = 5.2 A
Two 130 Ah batteries make total 260 Ah which draw 5.2 A. that would say 50 Hours. I'm I right?

 

[zaheer708]

Try using this ....

UPS Selector Sizing Applications

Thank u. Very good link indeed

 

[Golden_Boy]

I'm very sorry. Battery rating is 130Ah not 1300Ah. Human error.

Now can a 12V battery turn on a 240V-Light or fan?????

If total load is 1000 Watts or 1000/0.8 = 1250 VA and voltage is 240V. Then your current is 1250/240 = 5.2 A
Two 130 Ah batteries make total 260 Ah which draw 5.2 A. that would say 50 Hours. I'm I right?

That would be correct if you are supplying 5.2 amps AT 240 Volts BUT you can only supply that current at 12 volts , therefore at 240 the batteries will be flat after 2.5 hours. Allowinwing for efficiency 2 hours.

My brain is not working at the moment.......