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I saw this article this morning, and while it seemed fairly legitimate, I was skeptical about it. The claim is that if you drop a battery (flat end down) it will bounce higher/longer if the charge is gone then if it's fresh.

I figure if I had a volt-meter or the like I could probably test this myself, but I don't. A bit of googling didn't provide any results that I had a high amount of confidence in.

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    If you bounce it hard enough I'll guarantee it's uncharged. – Snakes and Coffee Apr 7 '15 at 19:59
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Yes, bouncing batteries tell you if they are charged or not.

The claim started with this YouTube video:

enter image description here

How To Test a AA battery, Easiest Way For Any Battery Fast, Easy!

After it went viral, scientists in the US have been curious, and later they confirmed that a simple bounce test can be used as a technique if a battery is charged.

A team led by Daniel Steingart of Princeton University, published their paper here, you can read it here.

As quoted by the study:

Recently there has been popular interest in the tendency of an alkaline AA battery to bounce after being dropped on its end when discharged to full capacity, compared to a flat landing with minimal bounce when the battery is “as-received”. In this paper the coefficient of restitution (COR) of an alkaline AA battery is measured at various depths of discharge by dropping the battery in a controlled fashion and observing the subsequent bouncing, and the change in COR is then compared to spatially resolved energy-dispersive X-ray diffraction (EDXRD) that was performed in situ on equivalent alkaline AA batteries. Our measurements show that this simple bounce test provides a considerable amount of information of the structure of the battery's Zn anode, rivaling the sensitivity of in situ EDXRD in detection of ZnO formation.


This discovery shows that nondestructive acoustic testing of batteries can provide valuable information about a battery's health and state of charge (SOC). Studies performed on other bobbin cell geometries (AAA, C and D alkaline cells) yield similar results.

According to scientificamerican.com, Daniel Steingart said:

We needed XRD to explain why the bounce changes this way, but once the correlation is made, a secondary school physics experiment can indicate where and how reactions are occurring in the battery.

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    But note that this only seems to apply to (non-rechargable) alkaline batteries. – jamesqf Apr 3 '15 at 21:42
  • Yes, I guess... – George Chalhoub Apr 3 '15 at 21:54
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This paper Bouncing Alkaline Batteries: A Basic Solution confirms the causal link between battery bounce characteristics and state of charge for selected battery chemistries and describes the mechanism imvolved. They say:

  • The coefficient of restitution of alkaline batteries has been shown to increase as a function of depth of discharge. In this work, using non-destructive mechanical testing, the change in coefficient of restitution is compared to in situ energy-dispersive x-ray diffraction data to determine the cause of the macroscopic change in coefficient of restitution. The increase in coefficient of restitution correlates to the formation of a percolation pathway of ZnO within the anode of the cell, and that the coefficient of restitution saturates at a value of 0.63 ± .05 at 50% state of charge when the anode has densified into porous ZnO solid. Of note is the sensitivity of coefficient of restitution to the amount of ZnO formation that rivals the sensitivity of in situ energy-dispersive x-ray diffraction spectroscopy.
    and
  • In this paper the coefficient of restitution (COR) of an alkaline AA battery is measured at various depths of discharge by dropping the battery in a controlled fashion and observing the subsequent bouncing. Our measurements show that this simple bounce test can provide a considerable amount of information of the structure of the battery’s Zn anode, rivaling the sensitivity of in situ energy-dispersive x-ray spectroscopy (EDXRD) in detection of ZnO formation. This discovery shows that non-destructive acoustic testing of batteries can provide valuable information about a battery’s health and state of charge (SOC).
    And
  • The densification of the anode affects the mechanical properties of the battery. The COR, which measures the elasticity of a collision between an object and a rigid object, is one such mechanical property that can be determined as shown in Eq. 5.
    COR = sqrt(h2/h1)
    where h1 is the drop height, and h2 is the maximum bounce height determined from Eq. 1. Using the bounce test described previously, the COR of alkaline batteries was measured through full discharge

Authors institutions: Andlinger Center for Energy and The Environment, Princeton University, , Department of Physics, Rutgers University, Piscataway, New Jersey, University of New York Energy Institute, New York, New York, Department of Chemical Engineering, City College of New York, New York, New York, Sustainable Technologies Division, Brookhaven National Laboratory, Upton, New York, National Synchrotron Light Source, Brookhaven National Laboratory, Upton, New York 11973, USA††

______________________________________________________

It definitely works for Alkaline batteries, which is what the detailed explanation relates to. THe probable reasons are well explained by the information provided by georgechalhoub. I'm just adding the observations of an experienced competent professional observer [tm] :-).

I am an electrical engineer with a Masters degree in EE and 50+ years experience with electronics. (Yes, we did have electronics "way back then"). I, too, was extremely sceptical when I read of this phenomenon. However, testing with dozens (probably ~= 50) of AA Alkaline batteries of a number of brands and states of charge showed and extremely large difference between fully charged and well used batteries. I did not carry out extensive tests with varying degrees of use - batteries here tend to be new, moderately well used or well used. Flattened to within a few mAh of their life tend to be thrown out asap.

As a means of sorting through a bag of mixed batteries to find unused ones this method works superbly. It is probably no quicker than using a test meter, bt hard flat surfaces are often easier to come by than multimeters "in the field".


Here are a series of reasonably well done experiments and battery dis-assemblies in a you tube video. This appears convincing but, of course, could be "cooked" if anyone wanted to spend the very extensive effort required to falsify results. There is no good reason to disbelieve what is shown here, but it's not peer reviewed and doesn't have a recognised institution name on it.

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    We don't allow answers based on personal expertise. Can you find some reputable sources that sustain your answer? – Sklivvz Apr 5 '15 at 17:53
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    @Sklivvz I am well aware of the strange, in my estimation, tendency of this forum to allow personal accounts that are reported from elsewhere but not by people reporting directly, even when they carefully describe circumstances of testing. If you wish to check how reputable my source is you can look at eg this web page or this list of references as a measure of bona fides. Should such not suffice, as I imagine may well prove to be the case .. – Russell McMahon Apr 6 '15 at 1:03
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    @Sklivvz ... disallow as you see fit. If you cannot allow eg Stack Exchange EE to become a source of credibility in its own right, what merit is there in allowing of material from other sources, which are often enough less reputable. Anyone who chooses to disbelieve an account that I offer on tests that I say I have carried out, where the procedures and degree (or lack) of formality are at least summarised, may do so as they choose. I suggest that the loss will usually be theirs. | I have read other accounts of tests carried out by persons who I consider competent and reliable. As ... – Russell McMahon Apr 6 '15 at 1:10
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    ... each of these is based on "personal expertise" we end up with (semi) infinite regress. Presumably one needs the name of an institution or faceless webpage to add notional credibility to such reports? – Russell McMahon Apr 6 '15 at 1:11
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    I understand your point - typically we rely on qualitative studies if possible, but the argument from personal authority is beyond what we can accept in general (think about things like "I'm a ufologist and I can certify aliens exist") – Sklivvz Apr 6 '15 at 14:03

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