Remember batteries with a quality meter on their side ?

[MathWizard]

Remember back when a lot of AA and similar batteries, had some strip on the side of them, that would change color, when pressed, to indicate the batteries charge/usefulness ?

So how did they actually work, and how much power did it use ? Did it drain the batteries much to check them ?? I'm guessing it was some chemically doped strip that responded to a voltage and/or current, with some color change.

Was it a bit of a scam ? (not everyone has a DMM) Especially knowing kids like me would be trying to check batteries for no reason ?

[xmris]

its the duracell powercheck, not sure what was the name for other brands, I am not expert on those, thermo-chromic  element/indicator.

[kjr18]

They were using material that changes colour depending on temperature, and small heater under it. With fresh battery you could achieve bigger temperature, with depleted battery only a little. For measuring if battery still has some useful energy, you need to test it under load. Not really a scam, but I think there was some other reason why they don't use this anymore.

[coppice]

The ones I remember had the problem that you had to squeeze them to turn on the measurement strip. However some battery holders could do the same thing, so the battery drained.

[AVGresponding]

The colour strip was a liquid crystal thermally sensitive display, much like those stick-on aquarium thermometers. As kjr18 says, it has a resistive heating element underneath it, and sucks a fair bit of current, shortening the life of the battery, particularly if you use it a lot.
I can imagine if the battery compartment is tight, it could activate and drain the cells in pretty short order, which might be why they stopped making them.

[MathWizard]

Ok I'm not surprised they went away then. My main memory of them is pressing the strip/button just to see if the color would actually change. And it didn't seem to work great, so I'd press the button even more...

It reminds me of ice cream that has stuff mixed with it, like chocolate chips. It so easy it just keep eating until you find another chocolate chip. And then you have to buy more.

[Vincent]

It was a toy, both metaphorically AND literally.

I liked pressing those as a kid. I was always like "lolol it changes colour!" 


...yup, that was a time before social media and smartphones!