When I started this hobby in 2012, lithium-ion batteries were quite rare then (specifically 18650s) and we have to settle with the usual ‘Fire’ batteries/light/charger combos.
I then bought the highly-regarded Pila IBC and the Maha C9000 to start it right.
When I became a member of both forum (CPF, then here), I became aware of the horrors, deceit and dangers of the ‘Fire’ batteries so I turned to discarded laptop batt packs just to get hold of Panasonic, LG, Samsung, Sony and Sanyo brands, after which I bought the iCharger 105B+ hobbycharger just to be able to analyze these cells.
Most laptop packs I got were perhaps discarded due to a hard use (except in some cases), most of them stayed at less than a volt for years.
Fast forward to today, and we arrive to the crux of this thread: In my experiences with cell revival or recovery from ultra-low stored voltage, I noticed that the Sanyos were the worst performer, meaning, most of them cannot be revived at all.
Even my brand-new ones lose their capacities faster than all the rest.
I have experimented with all those brands mentioned above, and noticed the LG brand as the most robust in revival percentage, with LG and Samsung as having high capacity retention among the and types currently available.
For the record I have opened almost fifty packs of different makes.
Even my brand new Sanyo 14500s that were accidentally over-discharged, three out of five were not able to make it back.