I have a Lenovo Z460 laptop that was actively used between 2011 and 2015. In 2015, its keyboard failed and so it became a spare laptop for me. It also had two battery packs: the original (from 2010) and a replacement (from 2012). As of 2015, both batteries were working perfectly fine, in my memory. So now in 2018... my new(er) laptop's keyboard has failed and I have gone back to using this Z460, while waiting for the replacement keyboard to arrive for the newer laptop. Upon charging the Z460's batteries, I discovered that the older pack tends to heat up quite a bit (pretty hot to touch, although not burning hot). The older pack also started charging at 0% - so it might have gone to sleep. The newer pack was connected to the laptop when I unpacked it, and it was recharged fine. So after cooling the older pack and letting it charge further, it seems to cut off at 99%. But was hot again. But after letting it cool again, it still seems to be able to hold its charge. I have been reading about the dangers of Li-on cells and this sounds... like it's time to part ways with the old pack? Well, it's not much of a loss because this laptop is really old, but I would like to know what this means, in case I ever run into something similar for other equipment. Thanks in advance.
