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UPS Sizing problem

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mathewkyle

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give 20% (of total power demand) for allowances due to losses. The battery can be discharged to 50% and inverter efficiency is 80%.I would like to use 12V, 200Ah batteries. I am told by an expert that I need 8 batteries. Is this true. And if so, please help me calculate. Please contact: <mailmekyle@gmail.com> Thank you.
 
that's good you put what batteries you are using but you need to state the power your "device" requires/consumes
 
I am terribly sorry. I missed the detail. The full details: 8 machines of 120W to run for 5 hours, 2 machines of 240W to run for 6 hours. 20% allowance for losses. Total power consumption is calculated as 9216W. Give 20% (of total power demand) for allowances due to losses. The battery can be discharged to 50% and inverter efficiency is 80%.I would like to use 12V, 200Ah batteries. I am told by an expert that I need 8 batteries. Is this true? And if so, please help me calculate. Please contact: <mailmekyle@gmail.com> Thank you.
 
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UPS issue

Hahaha. thanks for confirming, but please help me on HOW to determine this value. PS. it should be 9216Wh (check the units!) Thanks
 
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P = V * I

P*t = VI * t

12V * 200Ah = 2400Wh

2400 watt*hr * 8batteries =
19200Watthours total with 8 batteries

minus your efficiency percentages...... -50% - 20% -20%

gets you 7.2batteries, so round up

i did note your unit error
 
UPS help

Hi there. This looks crazy, but please help me go through the steps. Total Wh=9216. then due to battery discharge %age being 20%, coversion efficiency being 80%, then 9216/(200*12*0.8*0.5)=9.6 batteries. Where is the discepancy? This is getting to my head!
 
(8 * 120 * 5 ) + (2 * 240 * 6) = watthours for both machines = 7680Wh (plus 20%) = 9216Wh

plus another 20% for inverter efficiency = 11059Wh

12V@200Ah = 2400Wh per battery,,,, @ 50% that makes 1200Wh per battery.......


11059 / 1200 = 9.2 batteries you will neeed,,


seems my math was missing one of the percents!! :O
 
Hi, Its been some time, but I can still see you arrive at 9.2. So this is fine i guess?

But the issue is my "expert" insists it is 8 batteries.

Well, it can be his problem I feel.

Thanks anyway.
 
there is nothing saying my math is rite either, until someone else here confirms it!!

maybe get your experts algebra and post it for review, either way at least you got a estimate so you can do a "scratch test!"
 
I think you have counted the losses twice. The load is the load (no losses). The only loss is in the inverter. 8 on the button.
 
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