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In the movie Terminator 3: Rise of the Machines, Arnie's fuel cells were twice shown to be extremely devastating when their stored energy was released.

In real life, how many grams of, say, gunpowder or TNT are equivalent to the energy stored in

  1. An AA alkaline battery
  2. A laptop battery
  3. An electric car battery

Would the batteries be as devastating as the explosives if the energy could be released all at once (within milliseconds, say)? Presumably the power of chemical explosives come from the volume of gas they release...

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2 Answers 2

up vote 5 down vote accepted

One alkaline AA cell has about 11 kJ of energy. For a laptop battery, it is 360 kJ. Chevrolet Equinox Fuel Cell has 58 MJ of energy.

One kilogram of TNT carries about 4.184 MJ of energy. Divide the numbers from the previous paragraph by this constant to see that the AA cell, laptop battery, and electric car battery have 2.6 grams, 86 grams, or 14 kilograms of TNT. Note that TNT usually releases all the energy abruptly.

Gunpowder has 3 MJ per kg or so. It means you have to add about 35% to get the right estimate for the mass of equivalent gunpowder.

If you could release the energy from the batteries very quickly, the explosion could be equally devastating as the corresponding gunpowder and TNT except that batteries can't release energy this quickly.

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One AA battery doesn't have 11 kJ. They differ in real life, but for retail alkaline AA batteries, we're talking about 2.2 to 4.8 kJ. –  AlanSE Sep 19 '12 at 19:38
2  
Dear alan, click at my 11kJ - I provided a source for my claim, unlike you. –  Luboš Motl Sep 20 '12 at 5:10
    
en.wikipedia.org/wiki/AA_battery#Chemistry_and_capacity. Capacities are rather variable but Luboš's value of 11kJ for an AA alkaline battery seems about right. –  John Rennie Sep 20 '12 at 10:10
    
Sorry, the 11 kJ would be in the range of Alkaline or Li-FeS2 batteries as per Wikipedia en.wikipedia.org/wiki/AA_battery. The link given for the 11 kJ, however, gives me 22-23 kJ for all of the mouse models by multiplying (J/day)*(months*31). –  AlanSE Sep 20 '12 at 13:12
    
@AlanSE At the footer of the first page it says: "*Avg energy in 1 AA Alkaline cell approx. 11KJ". –  mmc Sep 21 '12 at 11:38

A battery's energy capacity is normally quoted in Amp-hour, (or mAh) the number of amps it could (in theory supply) for an hour. If you multiply this by the voltage you get energy. Specifically if you multiply by 3600 seconds in an hour you get Joules.

A NiHH rechargable AA cell is about 2200mAh and is 1.2V;
2200mA * 3600s * 1.2V = 9.5KJ,
an alkaline (ie Duracell) battery is similar

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