We use m12 small sized Milwaukee battery’s and I noticed when I use them I feel like they weigh different when using them sometimes while using them and then I read a article about batteries loosing mass but they were talking in the micron level and that didn’t seem to be the right path.

  • 2
    $\begingroup$ Yes, there is a weight difference, but you aren’t going to actually be able to feel it. $\endgroup$
    – Jon Custer
    Aug 18, 2023 at 1:58
  • $\begingroup$ For a point of reference, the weight of a paperclip contains about as much energy as was released by the first atomic bomb test. $\endgroup$
    – RC_23
    Aug 18, 2023 at 2:39
  • $\begingroup$ My immediate guess is that you're picking the battery, loading it, vibrating the heck out of your hands for an extended period with the power tool you loaded it into, and then unloading it to recharge - and all the vibrating makes your nervous system's interpretation of what you touch feel different. $\endgroup$
    – g s
    Aug 18, 2023 at 3:56

1 Answer 1


to detect a weight difference by hand would require a weight difference on the order of several grams. within your ability to measure the weight of a battery with a balance scale, there is no difference between the weight of a charged battery and a discharged battery. The electrochemical reactions that take place during the charge/discharge cycle of a battery do not involve any changes in mass (that is, mass is conserved in electrochemical reactions).

If you can get hold of a digital pan balance (as used for weighing food samples, shipped packages, etc.) try weighing the batteries before and after charging. This would be a fun and instructive experiment! And please report back here with your results. -NN


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