AA alkaline battery bounce test

[MichaelChang]

<p>Most of us use AA batteries in camera flashes, some photography accessories, and even in some cameras. Although Ni-MH is most popular these days, alkaline batteries is still an old standby we rely on.</p>

<p>It was observed that dead alkaline AA batteries bounce significantly more than a good one when dropped from a predetermined height. This video examines why:<br>

<a href="

- 5:31</p>

<p>Might be interesting to see if this applies to other battery chemistry types. </p>

 

[charles_stobbs3]

Do you have to take them out of the camera to perform this test or can you just drop the whole camera?

[Mike Gammill]

<p>Unless there is outgassing during discharge the mass should essentially be the same (conservation of mass). The amount of mass present in the container could influence "bounce" but I don't think that should change enough. Also the batteries would have to be dropped and hit the floor in a consistent way to lend validity to the test. Interesting idea, though. </p>

[jim_momary]

<p>As the video showed an "antibounce" hammer, more universally called a "dead blow" hammer ...</p>

<p>It's a "fluidic" mass that deadens rebound. Along the lines of plastic deformation v. elastic rebound, i.e. dropping a blob of Playdoh v. a large ball bearing. The "mushy" (fresh) battery <em>absorbs</em> the rebound potential with its momentum and reduces rebound. The dry battery (expended) results in a more elastic, <em>bouncy</em> rebound. <br>

Dead blow hammers have heads with a moveable slug of metal or filled with shot or shot in an oil based liquid (more expensive brands). The "dead blow" delivers more impact to the object being struck as it doesn't bounce off much at all.</p>

<p>Jim</p>

 

[lex_jenkins]

<p>Sounds like a witch test. If you drop a suspected witch and she bounces, she's a witch. If you drop her and she dies, she's not a witch. Or is it a duck?</p>

[dave_s]

<p>This is analogous to the well-known way to distinguish fresh eggs from boiled eggs: you put the egg on the counter, and spin it. I guess that has to do more with viscosity or something, rather than elasticity, but it's similar.</p>

[pjmeade]

That was tried live on the BBC and shown not to work.

[dave_s]

<p><em>Au contraire. </em> I once wowed a girlfriend who had mixed up fresh and hard-boiled eggs. She thought I was a genius.</p>

<p>(But I take your point. Maybe she brought one of the 'boiled' eggs to work, cracked it, and it ran all over her lunchbox.)</p>

[frode]

<p>The trick with spinning the fresh/boiled egg does work. I use it regularly to find out if an egg is boiled or not. I trust it 100%. We get fresh and boiled eggs mixed up in the fridge ever so often.<br>

;-)</p>

[Mike Gammill]

<p>I guess we could try spinning the batteries.;)</p>