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For some reason, I have been getting a lot of questions about
the possibility of 123A lithium cells exploding or causing
a flashlight to burst.
Some of this is the result of third-, fourth-, or fifth-party
stories about someone who had a flashlight burst, or someone
who heard about someone who read something on the internet
that a 123A powered flashlight burst, etc.
Some of it is due to marketers' fear-mongering in order to
sell products that don't use 123A cells and instead use alkalines
as a "safe alternative".
Could it happen to me?
Yes, it could happen.
You could also get struck by lightning next time you walk
outside.
A meteor could come crashing though your house.
Your computer monitor could burst into flames right now.
None of those things happening are very likely, are they?
Yes, I'm trying to make a point.
123A cells have been known to vent, outgas, and cause lights
to burst violently. Sort of like your chances of getting struck
by lightning or winning the lottery. It happens, but very
rarely.
When those unique and exceptional events happen, everyone
hears about them and then assumes it's the norm. This is how
insurance companies stay in business and why state lotteries
are so popular.
Chances are very good that you'll never have a problem with
123A cells. I have used many, many 123A lithium cell flashlights,
have burned through hundreds of 123A lithium cells, and have
never had a problem. In fact, millions of people have used
millions of 123A cell batteries without any problems.
Since there really aren't any statistical numbers related
to 123A cells bursting, I'm willing to bet that your chance
of getting into a car accident in your lifetime is much, much
higher than the chances of having one of your 123A cells burst
in a flashlight.
Why does it happen?
Keeping it simple, two things have to occur for a light
to burst:
1) First, you need something to create a lot of pressure.
When 123A lithium cells short out or overheat they release
a lot of energy very quickly in the form of hot gasses. This
creates the pressure. The main reason for this happening is
the use of two cells of different charge levels. When used,
the one good cell tries to both power the device and charge
the bad cell and one or both cells overheat. How can you tell
if you have a bad cell? Other than testing it, you can't.
2) Second, in order for a flashlight or anything else to
burst violently, you need an airtight container in which the
pressure can build up.
A metal flashlight with O-ring seals is very good at containing
pressure, to a point. When the pressure builds up enough,
something fails and it bursts. Since there is usually a lot
of pressure built up, pieces tend to fly at high enough velocity
to cut skin and damage property.
If the pressure cannot build up because the light isn't sealed
well, it will usually hiss or pop, release the pressure, and
we never hear about it from that person because it's "no
big deal".
How do I prevent it from happening?
Following some simple rules will help ensure that you don't
have any problems. As is to be expected, prevention is the
best medicine.
Use only good quality or proven brands, don't mix cell brands,
don't mix cells of different charge levels in the same device,
and don't mix-and-match partially used cells that you may
have lying around.
Although not a guarantee that you won't have any problems,
this will go a long way in helping.
If you have ever actually taken the time to read the instructions
for almost any flashlight, the advice above should sound familiar.
Really, this advice applies to all power storage cells, not
just 123A lithium cells. Lithium cells are a bit different
because of how quickly they can discharge all of their power.
This simple fact of their design makes caution more important,
but caution should be exercised with any power storage cells.
A trend has emerged that implicates 123A cells manufactured
in China as the major source of the "bursting cell"
problems. US supplied 123A cells (such as Duracell or Energizer)
are much more expensive and apparently have higher quality
control. The China supplied batteries are much cheaper (hence
their popularity) but consistency in performance seems to
be a bit of an issue. You could just buy US brands, but at
$10 a pair, it gets very expensive very fast.
For less than the cost of 3 pair of the US made cells, you
could invest in a tester and test the cells you buy. This
is probably a very good idea if you use inexpensive Chinese
manufactured cells. I use the ZTS
Mini-MBT which I recently picked up from Thomas
Distributing. The meter tells you if the cell is at <
20% capacity, 20%, 40%, 60%, 80% or 100%. When working with
multi-cell flashlights, I now make sure to use only cells
that have a matched initial state-of-charge. If a brand new
cell tests poorly, it's not necessarily dead. It should be
matched with another brand new cell that matches the test
results when used in multi-123A cell applications. I test
all my cells and label them with a sharpie marker. They get
one of the following numbers: 0 (< 20%), 2 (20%), 4 (40%),
6 (60%), 8 (80%), or 10 (100%). Only cells with the same number
are used together.
You could also use only single-123A cell lights. Some excellent
lights are powered by only one 123A cell. The few problems
that happen appear only to occur when you use more than one
123A cell in series.
An Experiment:
I tested a bunch of older inexpensive 123A cells I had lying
around. Testing cycle was repeated with a ZTS Mini-MBT tester
until 3 consistent readings were shown on the meter scale.
The meter reads < 20% (no reading), 20%, 40%, 60%, 80%,
100%. Batteries that read less than 100% aren't really dead
and may provide long runtimes. However they may not be delivering
the same current and/or voltage as cells with other readings.
Here are the results of testing 64 unused, shrink-wrapped
cells:
|
Charge Indicated
|
Number of Cells
|
|
100%
|
18
|
|
80%
|
8
|
|
60%
|
10
|
|
40%
|
10
|
|
20%
|
8
|
|
< 20%
|
10
|
Obviously I could have easily put a < 20% cell and a 100%
cell in the same light, but that doesn't mean that the batteries
would have burst. It does, however, mean that some of the
energy from that 100% cell is probably going to be wasted
trying to bring the < 20% cell up to par and the chances
of a burst cell are probably increased.
To discover the actual effect of mixing cells of different
known initial charge state, I did some runtimes with the same
2-cell light loaded with two < 20% cells, two 100% cells,
and with a single < 20% and 100% cell. I strongly recommend
against mixing cells of different known charge, so don't purposely
try this!
The runtimes were done with a Streamlight Scorpion, which
has a pretty strong constant draw on the cells. I did not
test the output for each of these combinations. I didn't use
a regulated light because I wanted to see the impact on the
runtime caused by a direct draw from the batteries.
Here are the results:
The red line is two cells that read 100% on the meter.
The blue line is two cells that read < 20% on the meter.
The green line is the result of mixing one "< 20%"
cell and one "100%" cell in the light.
Even though the blue line runtime was done with two cells
that read "< 20%" on the meter's display, they
provided decent runtime in the light, although reduced runtime
relative to two "100%" cells.
The most telling thing is that when the runtime was done
with one "100%" cell and one "< 20%",
runtime was reduced dramatically - even more so than running
with two "< 20%" cells.
Using matched cells in a light will apparently provide some
benefits, including increased runtimes and, I would expect,
reduced chances of having a cell burst.
Conclusion:
Don't let the fear of this rare event limit your illumination
options. Some of the brightest, lightest weight, and generally
"best" lights are powered by 123A lithium cells.
Often after trying one, it is practically impossible to go
back to that favorite old 2-AA alkaline light you've carried
for years. Take it from someone who has experienced this first-hand.
Be aware, however, that it CAN happen and take appropriate
precautions.
More Information:
For more information about a few actual documented incidents
of this happening, please see the following CandlePowerForums.com
threads. Registration is not required to read the articles.
Keep in mind that the folks frequenting the Forums collectively
burn through hundreds of thousands of 123A cells each year
and some of these reports are from incidents outside of the
forums.
http://candlepowerforums.com/vb/showthread.php?t=78843
http://candlepowerforums.com/vb/showthread.php?t=114455
One article at the GeoCaching forums where this happened
to one individual:
CPSC Recall page related to 123A cells bursting:
DOT Article regarding a fire caused by shipment of 123A
batteries damaged during offloading.
Information about 123A cells in general:
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