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I hope this is the best place for this question.

I have some Energizer lithium AA batteries (1.5v), that work very nicely in electronics that have heavy constant usage, such as my Apple Magic Trackpad. Some time back though, I found myself with a solar power unit from an outside patio umbrella (it had built-in lights), and noticed that the batteries inside were simply 3 generic AA cell nimh batteries. Just for kicks, I decided to see what would happen if I tried recharging some of my AA Lithium batteries.

They charge very, very slowly of course, but it definitely works. The batteries get up to a voltage (as read by a voltmeter) of 1.6v, but I've noticed that they don't hold their charge anywhere near as long as they originally did. It's a rough guess but I'd say I probably get about 20% of the original lifespan of the battery. Still feels kinda cool to be using the sun's energy rather than throwing them batteries out each time.

So I guess my question is in a few parts...

  1. Are there any downsides to recharging these batteries in this way?
  2. Why is the lifespan so drastically reduced?
  3. Is there a way to increase the lifespan after recharging?
  4. Is there anything else I should know with regard to recharging batteries like this?
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  • \$\begingroup\$ what about recharging batteries that were made to be rechargeable in the first place? \$\endgroup\$ – Wesley Lee Dec 26 '16 at 23:57
  • \$\begingroup\$ Well sure that would work fine. But I just happen to have these Lithiums, and no officially-rechargeable batteries. \$\endgroup\$ – Jonathan van Clute Dec 26 '16 at 23:58
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    \$\begingroup\$ See the datasheet data.energizer.com/PDFs/lithiuml91l92_appman.pdf you might get away with this but nobody here is going to tell you it is a good idea. \$\endgroup\$ – RoyC Dec 27 '16 at 0:08
  • \$\begingroup\$ I guess this is a very interesting question, on how to deal with discharged batteries.... If a procedure for charging them would be possible to be achievable... \$\endgroup\$ – Brethlosze Dec 28 '16 at 5:15
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  1. Lithium Primary batteries are not meant to be recharge. Can you physically recharge them? As you noticed, yes, but it's not a good idea. They can explode from this. To be honest, if they could be recharged, Energizer would market them like that. If they could be recharged and life expanded, they would have found a way, considering how many billions they have in funds.

    If you want to recharge lithium batteries, get standard lithium secondary cells.

    In fact, you "measuring it" at 1.6V means its DEAD:

    A “good” battery will generally have an Open Circuit Voltage (OCV) >1.74 volts. Any battery with an OCV <1.70 (after it has been allowed to recover) is completely discharged. Although an alkaline battery may read “good” at 1.6 volts, this reading on a LiFeS2 battery indicates the product has been discharged.

  2. The reason the lifespan has shorten is because of the chemical reaction converting the chemicals that make up the cell as the battery drains. Simply charging it does not undue this basic chemical change.

3. NO.

4. DON'T.

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  • \$\begingroup\$ Thanks but you didn't address much of my question. I'm aware of all of this, and this is why I only chose to do this because I have this solar charger which charges extremely slowly and (I believe) would be unlikely to dangerously overcharge. I have no interest in buying separate rechargeable batteries, I originally intended these to be disposables, I just tried charging them out of curiosity and now would like some input on the details as stated. \$\endgroup\$ – Jonathan van Clute Dec 27 '16 at 0:05
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    \$\begingroup\$ @JonathanvanClute directly address all 4 points. \$\endgroup\$ – Passerby Dec 27 '16 at 0:33

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