Sebastian Köln wrote:EDIT: I completely forgot the important part:
A Lithium Battery pack needs a balancer and in your case also a protection circuit that cuts the power off if any cell gets discharged too much.
Sebastian, thanks — you've provided much useful info and I hope Permies members will read it and maybe follow it up, if it is apt for them. But unfortunately it's not 'in my case' since the machines belong to members of three households, none of which is
my household. I believe none of these people would want to go into the innards of their power cells. They all seem to be at the point where they will buy another battery pack, or wish to know where they
can by one affordably if they need it.