Recovering a "dead" lithium battery

[jdurand]

They do, but the problem is even the circuit to disconnect takes a tiny bit of current. A DW01 is a super common little low-voltage cutoff chip, and it's quiescent current (nerd speak for the amount of current something draws when it's off) is around 3 micro amps. So 3 millionths of an amp. Normally this is smaller than the self-discharge of the battery so we don't care. But it all adds up and eventually destroy the cell if you leave it long enough.

And it's even worse if they use their microcontroller in place of the DW01. I think that's the problem with the battery welder, they mention they have all sorts of over temp and over current protections for the battery. So, they probably do it all with their processor and that would be why this ran down in about 6 months.