[time-nuts] Li-ion Battreries

[Chris Albertson]

On Sun, Jan 22, 2017 at 9:36 AM, Mark Sims <holrum at hotmail.com> wrote:

> I have a LOT of experience in testing and using 18650 cells.   It is a
> horrible place for the un-initiated to be.  The market is so saturated with
> dangerous fakes and inferior, over-speced cells that finding a genuine cell
> is a vanishingly small probability.  Hopefully the seller mentioned before
> pans out and sticks around.


I agree, many fakes.  But you CAN buy through reputable distributes like
Amazon.com  for maybe $16 per cell.

When I buy a battery packs the cells are already shrink wrapped and who
knows what is really inside, so I test the pack.  I charge it up and then
discharge it through a dummy load and track the power over time (actually
my programable charger can do this for me) then I recharge it ti to "stage
age voltage" and check that the self-discharge rate is reasonable.  I've
not had a problem with hobby type drone batteries and if I did I'd be
covered by even a 30 day warranty or failing that by PayPall's chargeback
policy.

I'd 100% recommend that anyone who buys a lithium battery place it inside a
fire proof enclosure then run it through a few charge/discharge cycles and
very the seller's specifications.   If you are not set up to do this kind
of acceptance testing don't buy lithium.

I can say first hand that once the lion battery fails, boiling electrolyte
and white smoke will continue to come out of the battery no batter what you
do, just take it outdoors and set it on the concrete and let it finish,
dropping the assembly in a bucket of water will not help, they will
generate a few hundred watts of heat until they run out of energy.  One
started it is a positive feedback loop.  But not dangerous if you thought
ahead to place the thing inside some metal container.  Just carry the
smoking mess outdoors and leave it there for a while.    (I tried salvaging
lithium cells for Milwaukee power tools with only about 50% success rate)


-- 

Chris Albertson
Redondo Beach, California