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What are the most recommended circuits and equipment for testing AA and AAA alkaline batteries used in household items?

And are there any useful applications of weak batteries which still have a little amount of power in them? Like an AA battery with voltage and current measurements of 1.20 V and 0.2 A. If they can even light an LED for several hours with that power, it'd be good.

I'd also like to know What is the definition of a dead battery and when it is recommended to throw them out without wasting its remaining power?

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  • \$\begingroup\$ If you really wanted to maximize use from all of your dead batteries, you could build a custom circuit to drain them, perhaps something a bit more complicated than a joule thief like a bank of them with some amount of power point tracking to charge a battery+capacitor bank in parallel, with the option of charging an external device like a phone as a priority when the capacitor bank fills up, and the internal battery bank secondarily. To really milk them you have to drain each cell as slowly as possible. \$\endgroup\$
    – K H
    Sep 24 '18 at 1:17
  • \$\begingroup\$ for about a dollar or so on ebay you can get a BL8530/BL8531 can drive an led (with a resistor) for a while, or do other stuff. arguably they are never dead the chemicals/materials have value/life although how hard to do that I dont know, but assume that some day there will be a process. \$\endgroup\$
    – old_timer
    Sep 24 '18 at 3:16
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    \$\begingroup\$ In Philadelphia it is popular to throw them at pro athletes. For safety reasons they try to limit the battery sizes to 9V and AAA. Getting pelted by D-Cells has been reported. \$\endgroup\$ Sep 24 '18 at 4:00
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    \$\begingroup\$ @Misunderstood What the hell?! \$\endgroup\$ Sep 24 '18 at 6:39
  • \$\begingroup\$ AAA batteries are smaller and sold in bunches, so you could conceivably arm yourself with a sort of battery spray. D-cells don't make good sense. If you want to hit a guy with a battery, use 9V's or AAA's. sbnation.com/mlb/2011/3/11/2044411/… \$\endgroup\$ Sep 24 '18 at 6:53
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Check out the Joule Circuit https://makezine.com/projects/joule-thief-battery-charger/

It's capable of working with very dead batteries, but overall the internal resistance of dead batteries impractical to use in many applications.

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There is nothing that a weak/dead battery can do that a fresh battery can't do better — other than fail or leak sooner.

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The best application for a weak or dead battery is an appropriate recycling scheme so it is disposed of correctly.

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Generally, if I find an alkaline battery lying around, I just measure the voltage. If the voltage at room temperature is over 1.5V, the battery is still mostly good. If it is between 1.5 and 1.4, I might keep it to use by itself or with another battery of same voltage. Below that, the battery is basically dead and not worth keeping.

Note that this only applies to open-circuit voltage of batteries which have been resting. During discharge, alkaline battery voltage sags a lot. An alkaline battery can be discharged with heavy load down to 1V and bounce back up to 1.4V after the load is removed and the battery is allowed to rest.

In my opinion, dead alkaline batteries should be disposed of according to applicable regulations. But some people do recharge them and use them in clocks or remotes or wireless computer mouses or what have you. I don't know the details of how the recharging is done. It is not a recommended practice and doesn't restore the battery to like-new condition. To me it is just a waste of time.

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  • \$\begingroup\$ Why do you say you would keep it to use with another battery of the same voltage? Why does it matter if you add them in series? \$\endgroup\$ Sep 24 '18 at 6:37
  • \$\begingroup\$ It is better if the two batteries run out of energy at the same time. That way you get the most out of them. \$\endgroup\$
    – mkeith
    Sep 24 '18 at 13:58
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Search Eveready battery VI load curves for remaining capacity and then consider 2V RED/YELLOW LEDs with current limit including battery ESR when using 2 in series.or 3V White 5mm LEDs if using 3 cells in seriies. Normally 1V is near empty but not quite. Series cells work best when matched from weak link theory. Batteries and LEDs have a certain series R but when you add a series R=V/I you can consider battery R rises sharply when drained

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