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### Topic: how long would a 1.2v 5ah battery run with a power draw of 100w? (Read 1 time)previous topic - next topic

#### AP14

##### Apr 25, 2014, 05:58 pm
And how would you set up the equation to find the answer?

#### MarkG

#1

#2
##### Apr 25, 2014, 08:08 pm
Well P = IV, current x voltage.
5A x 1.2V = 6W.
So 100W is not achievable for any length of time.
Designing & building electrical circuits for over 25 years.  Screw Shield for Mega/Due/Uno,  Bobuino with ATMega1284P, & other '328P & '1284P creations & offerings at  my website.

#### Paul__B

#3
##### Apr 26, 2014, 06:47 am

Well P = IV, current x voltage.
5A x 1.2V = 6W.

Or in this case, 6 Watt-hours.  6/100 x 60 = 3.6 minutes if the battery could sustain this discharge, however it would have to to deliver 80 amps to do this which is particularly unlikely, even for a nickel-cadmium.

Depending on the chemistry, there may be other consequences.  If for example this was a lithium-ion, it may be difficult to find where the battery was beyond the initial two minutes - after you are discharged from hospital, that is.

On the other hand, for a 12V battery, this question becomes more meaningful (about 15 to 20 minutes).

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