On Dec 22, 2022, at 6:30 PM, Will Cooke via cctalk
<cctalk(a)classiccmp.org> wrote:
On 12/22/2022 4:34 PM CST Chuck Guzis via cctalk
<cctalk(a)classiccmp.org> wrote:
That's not to say that Li-ion cells are without their quirks. I
recently almost discarded a AA-sized 14500 cell because the output
voltage had suddenly dropped to the point where none of my chargers
would even see it. So I put it on a corner of my workbench against the
time when I had accumulated several and could turn them in for
disposal. A couple of days ago, I picked up the cell and checked it
with my voltmeter and it read 3.5V. Put it in the charger, and slowly
charged to capacity. What happened during the month or so that it sat
on my workbench, I cannot say.
--Chuck
A VERY large percentage of LiIon batteries have a protection circuit built in to prevent
over-discharge. Even a lot of the "standard" cell types (e.g. 18650s) The
circuit disconnects the battery from its terminals if the voltage drops too low, showing
near 0 volts out. If it just barely meets the cutoff, it may recover enough to
re-activate the circuit, making it possible to recharge it. Often, you can open the case,
skip over the circuit board to access the battery cell directly, and add a small amount of
charge to reactivate it. Then it will work normally. I've done this a few times.
Will
That rings a bell. The battery chapter I mentioned says that Li cells need protective
circuits, so any loose cells or battery assemblies you buy have that built-in as a
standard component. The only people who get to see bare cells are those who assemble
their own battery packs. So car makers take in 18650 cells by the shipload, without
built-in protection because they supply that protection as part of their packs. But when
ordinary civilians buy lithium cells we get protected ones.
paul