Don't they degrade chemically after 13 years or so ?
They do, but most are still usable. That Li-ion battery I've put in the weight-scale is from around 2005, 20 years ago and still doing OK. I have many other from old 2G mobile phones, the kind of phones with physical buttons for the numerical keypad, 10-20 years old. Many of their batteries are still usable.
Some may look bulged, but not all of them, and they usually have only 50-70% left from their nominal mAh, but still usable.
Same for very old NiMH or NiCd that were used in the very first mobile phones, before Li-ion became the norm. Still usable batteries, but with lower capacity. In fact the failure rate of Li-ion is much lower, followed by NiMH (with much higher failure than Li-ion). From the NiCd, only a few of them survived, but I still have some 300mAh AAA NiCd in use inside of a hallway light activated by an IR motion sensor. Once charged they last about 2 month, and I suspect most of the charge loss is caused by self-discharge.
Another reused batteries tale (though not Li-ion, this time NiMH), my DMM accepts 3 x AA, either alkaline or recheargeables. Since it has an internal recharger that is almost always plugged into mains, inside the DMM I've put 3 Ni-MH cells cut out from a pack of 5 that used to power an ancient Motorola 8700 MicroTac, from the 90s!
https://en.wikipedia.org/wiki/Motorola_MicroTACThe funny thing is that I've found the Motorola battery while cleaning the lab, forgoten in one of the scrap boxes from decades ago. Measured the pack out of curiosity, and it was not zero, which came intriguing. These were NiMH, and supposed to have a pretty big self-discharge rate (when compared to Li-ion).
Opened the battery pack, and 3 out of 5 NiMH cells were still usable, charged them at the beginning of the year, and more than 6 months later they were still keeping their charge (left unused). So i've put them inside the DMM, more like an homage (they have about half of their nominal 700mAh, which means only about 10 hours on for the mtx3283 DMM, though the DMM is plugged into mains most of the time, which makes the battery capacity irrelevant).
Attached is the discharging chart of the 3 still usable cells out of that pack of 5. They were measured at 140mA constant discharging current (0.2 of nominal C=700mAh). Note the mAh in the upper right corner, that is the true value calculated from the measured I/V plots of each cell, and it's about half their nominal C.
The short circuit current (after letting them charged for about half a year) was still noticeable, about 1-2A. For the internal resistance of my DMM, the normal I short for NiMH is about 2A for 10-20 years old ones, and about 10A for brand new NiMH cells.
What was absolutely puzzling (about those 5 NiMH from the Motorola phone) was that one of the cells, the one in the middle, was measuring only 0.2V instead of 1.2V, yet it was able to deliver energy and some short-circuit current at that 0.2V nominal.
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