[Tfug] Follow-up: Li-ion battery charging problem

[John Karns]

A few weeks ago I posted about a newly received replacement battery
that I had deep-cycle discharged and that subsequently would not
accept a charge.  The problem remained after stashing it in the fridge
for several hours.  Ditto after a short heat treatment.  The idea was
to jolt the chemistry.

I tried again after leaving it alone for a week or so - no luck.  So I
tried it again after about 3 weeks, and lo, and behold, the it
accepted a charge.  I took two attempts, though - the first time I put
it in the machine, the charge light came on, but then started flashing
again after a second or two.  Pulled it out, and tried again - and it
went to full charge.  Guess persistence pays.  I was glad I didn't
just toss it out after having so many failures.

My guess is that the temperature treatments were superfluous, but
there is some voltage threshold that the internal voltage has to
exceed before the cells will accept a charge, and leaving it set for
an relatively extended period allowed the chemistry to bounce back
enough to reach or exceed the threshold.

Don't think I'll be deep discharging any rechargeable batteries again
anytime soon.  Not intentionally, at least.

-- 
John