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Which is a better buy: cheap or expensive batteries?

What do watermelons in a slingshot and battery selection have in common?  Rhett Allain.  He’s a physics professor who blogs about science, technology and geeky things.
Batteries
Watermelons in a slingshot:
A few years ago, a competitive reality show, The Amazing Race, had a "watermelons in a slingshot" competition.  Think Angry Birds...but different.  Based on the show’s video, Rhett calculated both the speed and impact, OUCH!, of the watermelon.

Battery selection:
Ever wonder which is a better buy, cheap or expensive batteries?  Earlier this week, Rhett deciphered the answer to this question by breaking this down into two separate questions:

  • “How much energy is stored in the battery?” and
  • “What does the battery cost?” 


The professor made measurements and ran calculations on Energizer, Duracell and Dollar Store batteries. 

Results: The more expensive batteries stored more energy.  But, what happens if you divide the energy by battery cost?  He terms this the “money-energy density”.  Which battery has the best money-energy density?  Basically, all three batteries have a similar money-energy density.  Is that what you would have guessed?

Rhett notes however that how the battery is used may be a determinant as to which type to select.  For example, some electronics do not function below a certain power threshold: think Wii or battery-powered objects that move.  The cheaper battery looses power fairly rapidly so this may be an issue with power-sensitive electronics.

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