It's the Makita............."FLEET!!"....and a couple others

The BIG problem with Li-Ion or lithium, "anything" is that they are nearly impossible to rebuild. You really are not supposed to solder them. Spot weld The cells must be balanced within tenths of volts or the management hardware will not play. I've read on the WWW that the newer Makita batteries with the "star" on the battery will brick the board if you try to rebuild them. I've also read there are replacement boards (china of course) avail. So I HOPE these batteries are avail until I'm too old or worse.

The one good thing about Li batteries is that they
seem to be less fussy about being left around not fully charged, and don't discharge as badly as the older tech.