Where
do you store and charge your Lithium batteries? Have
you given much thought to that? Unfortunately, there has
been another fire that took an AMA member's house, but
luckily it did not result in any injuries or loss of life.
This time the situation concerns me more than past
instances. In this case the modeler reportedly had taken the
battery off of charge and placed it on the bench while he
went into the house for dinner. That is right—the battery was
not connected to the charger when it burst into
flames and set the wooden bench and surrounding material on
fire.
The fire consumed the entire house but the modeler and
his family were able to get out, safely.
This incident,
which has not been fully investigated as I am writing this,
brings up a new, potential problem and it is one from which
we can all learn. Before this episode, I had never heard of
a fire started by a battery that had been taken off the
charger unless it had been visibly swollen during the
charging process or had physical damage.
From the report I
received, this battery did not show any damage or swelling
when it was removed from the charger so it should have
created a miniscule threat for fire.
Did the modeler look
the battery over carefully? Had it started swelling but it
was not apparent? Was it excessively hot? What charger and
charging rate were used? Was the pack balanced during the
charging process?
We still have many questions at this
point, but that does not mean that we should ignore the
incident.
I have gotten involved in electric helicopter
flying, and in the course of this have had an opportunity to
see various methods of handling batteries during charging
and storage. I've seen the whole spectrum of care being
given to these processes. I've seen batteries thrown onto
paper sacks, laying loose in toolboxes, secured in fireproof
vaults, in a product called the LipoSack, and in a Battery
Bunker charging container.
During transport, charging, and
storage, is there a correct way to handle these batteries?
No, there is not, but there are "smart" ways and
"not-so-smart" ways.
Fortunately, fires with Lithium
batteries are still somewhat rare, but when they happen,
they are serious. The rarity of an occurrence has a tendency
to lull us into the habit of using bad practices in handling
these batteries. If you use rechargeable Lithium batteries
of any type, it is in your best interest to respect the
dangers and to handle them with appropriate care.
Personally, I prefer to store and transport them in a
fireproof container. I use a LipoSack for this purpose, and
I like to charge them in this sack or in a Battery Bunker.
Chargers are another potential source of difficulty and many
of them charge through the two-wire output plug, ignoring
the balance (node) connector which is there to monitor the
status of each cell in the pack. I would not use a charger
without some form of balancer.
A large number of the fires
that have been reported to me involve chargers that do not
have any active balancing component. It does not matter if
this feature is a part of the charger itself or as a
separate component that plugs in, but the continued charging
of Lithium batteries without a balancing system can lead to
trouble.
I'm amazed when I hear from people in person and on
Web sites that they are going to buy a balancer when they
can afford one, but they keep charging and using the
batteries in the meantime. This can be a dangerous game of
roulette and it's putting your property and your family in
jeopardy. Please do not do this! Imbalance in the cells in
the battery is the most likely cause of swelling in a cell
and an ensuing fire.
I'm also astounded when I hear or read
about people who are still using batteries that are visibly
swollen. I even came across an advertisement on eBay in
which the items being sold were Lithium batteries that were
"only slightly swollen." I hope you were not the person who
bought them! MA
Til next month ...
Dave Brown, AMA president
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