Help Calculate Runtime

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GREG3f
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Help Calculate Runtime

Wed Apr 25, 2018 7:55 pm

I have a WS-12-250-AC that draws aprox 50w according to the Bar at the top of the gui.

Now this switch is running on a UPS that has a 700w AC Inverter/Charger with a 100amp/h 12v Battery.

How can I estimate the runtime of this switch when running solely on battery?

Looking for the right formula to make this estimate so any help is appreciated.

Julian
 

Re: Help Calculate Runtime

Wed Apr 25, 2018 8:42 pm

The best place to start would be putting an ammeter between the battery and inverter - this will give you a very clear idea of how many amps you're drawing.

Since we don't have that, here's an example of the power math.

50w / (approximate efficiency of inverter, say 80%) is 62.5w, which at 12 v is 5.2A. Watts = Volts * Amps.

When you're trying to figure out how many hours your battery will last, you: (rated amp hours)/(amps)=Hours, so 100/5.2= 19.23 hours, or 19 hours and 13 minutes. Battery Capacity = Amps * Hours.

That's the gist of the math, anyway.

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