There is no soldering to make this extremely easy tiny battery tester..

You can keep the tester in your very smallest pocket..

Take a careful look at Battery caused LED brightness.

And there are other uses for these component parts.

Step 1: Parts

Wondermagnet.com supplied the NdFeB Neodymium-Iron-Boron Rod magnets for this project.

Top  magnet  ¼"dia × ¼ "long rod
Base magnet ¼"dia × ½"long rod

Safety Notes

Please do not let little children play, mouth, or risk swallowing these attractive magnets,
a serious surgical situation may result if swallowed.
Also take care to restrict access to  the little button batteries which may contain mercury.

I take no responsibility for any mishap, or injury that may result or occur now or at some later time because of this project..
Is this a "go/no go" tester with no gray areas? I have used some coin batteries that seem to have a threshold below which they do not power the device, but still seem to have quite a bit of life left for other uses.
This LED battery tester is more then a &quot;go no/go&quot; pictures 4, 5 and 6<br> in the first step are different battery conditions with different<br> LED intensities.&nbsp;<br> You very are correct some applications can use the last dregs of<br> a coin cell like a Joule Thief light verses some radios or hearing aids<br> I have known.<br> <br> You know our eyes respond logarithmically to light while the LED is<br> more linear to battery energy near its end of life curve and depends<br> on battery type.&nbsp; That is a reason why the electric meter came about.<br> <br> This tester in the best use is a comparison of the same type of coin cells.<br> I can easily grade a group of cells to eight levels if I put my eyes to it.<br> <br> Then the magnets in the plastic compartments try to hold the cells from shorting each other out.<br> <br> A<br>
Looks rather handy to have. Thanks for sharing. :)
Happy to do so :)<br> <br> Are you going to award patches for total views for&nbsp; Jayefuu and HQ<br> <br> <img alt="Date Joined" src="https://www.instructables.com/static/img/profile/joined.png" title="Date Joined">
Hey... who told? lol <br> <br>I've been working on several new ones actually including total views. Jayefuu likes that one the best right now, so I have to try and up the ante... hehe
Well.... I follow you both and can read<br> <sub>&nbsp;&nbsp; between</sub><br> the lines as it were<sub>..</sub><br>
Mighty sly of you.... <br> <br>I best watch what I say between the lines as it were... :)
Very interesting! Both useful and compact! <br>-BLUEBLOBS2
Thanks for the nice comment.<br> <br> A

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