Products > Dodgy Technology
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.
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