Watt-hour to Amp-hr conversion

Thread Starter

anony

Joined Apr 3, 2010
12
hello,
i have a system that consumes 95.76 Wh of energy. I want to calculate how many AA batteries will be required to run this system for 14 hrs
Can some one please help me with this conversion?
Thankyou
 

Thread Starter

anony

Joined Apr 3, 2010
12
okie....sorr but now i m bit confuse about it. what about the resistance ? If the current is constant the resistance value will not matter for calcuting the battery usage?
and i read that AA batteries have arround 400-900 mamp-hr capacity so for my problem two AA batteries will be enough?
Thanks
 

Jony130

Joined Feb 17, 2009
5,145
Well in real situation resistance do matter. Because when cell is discharge the voltage on the cell drop so current will me drop to.
And this is so we need more mAh cell then in theory.
 

Thread Starter

anony

Joined Apr 3, 2010
12
the system i need to run with AA batteries is giving constant dc current of 40 mA in form of pulses ( frequency of 200 hz with high time of 120 microsec). So the On time for pulse in one hour is= .024 hr ( is it right ??)

To calculate the AA batteries that can run the system . Can i use this equation
(40 mA) * (.024 hr) = 0.96 mAmp-hr

It means that one AA battery is enough ??
and also can i calcualte the battery usuage like this?
Thankyou
 

Jony130

Joined Feb 17, 2009
5,145
For F=200Hz an Ton = 120uA the average current will be equal:
Iavr = 40mA * 0.12ms/5ms ≈ 1mA
So you don't have to be worry about battery capacity, 400-900mAh will be enough.
 
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