Duracell power Check feature? 1

I believe that they're using thermotropic liquid crystal, like you see on some aquarium thermometers. When you push the two points on the battery, you're really just connecting a resistor across it. The resistor heats up and the liquid crystal color changes.

Go to do a patent search on assignee of Duracell.

Here's an abstract from patent # 5,612,151

A label for an electrochemical cell with a condition tester for the cell integrated with the label to form a label/tester composite is disclosed. The label/tester composite has a thermochromic material in thermal contact with an electrically conductive material. A substructure containing a cured conductive material and preferably also a thermochromic material is formed on a releasable web and transferred from the releasable web to the inside surface of the heat shrinkable base film. A partition coating may be applied over the transferred conductive material. Preferably, a sheet of paper or plastic film having a large window opening therein for entrapping air is applied over the partition coating and aligned over the heat generating portion of the conductive material. The label/tester composite is applied to the cell housing with the insulating paper or plastic film with window opening against the cell housing. The tester may be activated by depressing one or two regions on its surface thereby connecting the conductive material to the terminals of the cell, whereupon the conductive material becomes heated causing a change in appearance of the thermochromic material to indicate the condition of the cell.

Didn't this feature go away? I haven't seen it lately. But then again I use NiMH

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A marvel of marketing! Include a device that uses up power so you need to buy another battery sooner.

Thanks everyone! This is what i needed to know!

Thermochromic dye is cool stuff, I used to have a thermochromic t-shirt, it was constantly changing color.


JRaef.com
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"...uses up power so you need to buy another battery sooner."

On the Duracell cells, there was one or two white spots (buttons) that had to be pressed to complete the circuit. So the indicator only used power for the few seconds that you pressed the buttons. If they hadn't included the series switches, then the battery would probably have been dead before it left the warehouse.

I never used those wormy testers..

Keith Cress
Flamin Systems, Inc.-

I never thought that they worked particularly well. It took a lot of effort to make connection and sometimes, it wasn't obvious that a connection was made at all.

TTFN

QED

Keith Cress
Flamin Systems, Inc.-

They used to make a stand alone battery test strip about 4 inches long you could use for checking just about any 1.5 volt cylindrical battery. I think I got them from multi-packs of batteries. Hooked up to an appropriate circuit, they made a cheap panel indicator. Audio power amplifier output voltage, that sort of thing.

Not accurate by any means, but handy when you just want a visual indication of activity.

A power indicator on each battery to confirm that the contacts on your flashlight are oxidized but the battery still has juice. That was quite a marketing feat. I wonder if it increased their market share.

Hiya-

I like jimkirk's idea. That's cute! I can envision a
problem soldering wires onto the contacts of the "display",
but I guess some sort of compression connection would
work as well.

Thanks for the thought. If I were in high school (oh
that was MANY years ago) it would make an interesting
science fair project.

However, even today, that's something to think about.
Thanks for the thought. I'll "star" your post.

Cheers,

Rich S.

Everyone has a free, personal 9V battery tester:
Press the contacts against your tongue and feel the burn!

I had an old Aunt who asked how to check if a 9v battery was fresh - I told her about the tongue test and she promptly tried it with an out of the carton example.

Can tell you my ass was sore from the kicking I got from my father (I was 9 at the time)

Was way cool to see her face though !

Rugged

I love the taste of electrons in the morning...

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"It's the questions that drive us"
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