Is it possible? I know lithium ion batteries are rechargeable, and I've got a few 3V lithium ion coin cells (two I pulled out of a calculator, and one's from an old watch). Since usually people just throw these away and buy new ones, are they rechargeable? Or is there something that prevents me from charging them? If it means anything, two are marked "Panasonic CR2025" and one is marked "Maxell CR2016." Also, if they are rechargeable, how would I charge them?

 

Well, knowing that cell phone batteries are made from lithium-ion battery types, i guess that would mean that you could charge them. But you have to make sure they are lithium types. Them cheapy' china made one are not.

Just find some way to apply something like 5 volts to them at a very low current, like 5ma.

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I believe these are primary Lithium cells, and are therefore non-rechargeable. There are some coin-type Li cells that are rechargeable, but you would typically not find them in calculators. Theya re typically charged from a constant current (a couple of mA), voltage limited (3.3V max.) source.

BTW, the 2025 means 20mm diameter, and 2.5mm thickness. Same rules applie to CR2016 and 2032.