weight of the power source. Today many
models have a dozen or more servos which
would have required a pound or more of
batteries in the past. These newer batteries are
wonderful but they are not without their
problems, and those problems involve safety.
A good way to refer to the situation
created by advancing technologies is as a
“wonderful curse.” It is apparent that new
technology in batteries is creating some
significant safety hazards.
Lithium, the principal chemical in these
batteries, is highly flammable and requires
additional care. Even without the fire hazards,
the increased energy density of the new
batteries would require added caution, but
with it, the need for concern becomes
imperative. I am not an expert in battery use
in any way, so the information I will pass on
is what I have been told or observed.
Lithium batteries come in many types
including those nonrechargeable AA batteries
you see at Wal-Mart which work well in
applications where most others won’t work
because of low temperatures, and the
rechargeable battery pack in your laptop.
Many cellular telephones and personal digital
assistants (PDAs) use rechargeable Lithium
cells and newer ones use Li-Poly cells.
Rechargeable Lithium batteries are
commonly available in two types, Lithium-
Ion, commonly referred to as “Li-Ion,” and
Lithium-Polymer or “Li-Poly” cells. Properly
used, either technology is safe. The devices
they are in are allowed onto commercial
aircraft every day.
The problem is that they are intolerant of
misuse, particularly when charging them.
Unlike the Ni-Cd batteries, these will not
tolerate any overcharging and will explode
violently.
Most of us realize that Ni-Cds will
explode if they are abused enough, but this
isn’t the same thing. Ni-Cds explode and the
worst problem is the possibility of shrapnel.
WHAT ATTRACTS many to the wonderful
world of aeromodeling is the opportunity to
realize the benefits of so many technologies.
When I consider how far advancing
technologies have brought us in the time I
have been involved in the sport—nearly a
half century—it is mind-boggling. I began
aeromodeling shortly after melting
toothbrush handles for glue was the standard.
Points, condensers, A and B batteries,
silk, dope, pneumatic timers, and many other
items—my grandchildren would call this
stuff medieval—were the tools of the day.
What about high-tech adhesives? Ambroid
was our high-tech adhesive.
I remember those state-of-the-art radios
which used “miniature” gas tubes, and
incredibly, were hand-held! Throttles that
worked were a big advancement. Servos
replaced those pesky escapements with their
rubber bands which always failed—or we
forgot to wind them—at the worst time.
Castor oil was the standard in our fuels,
and dealing with varnish didn’t mean you
were painting anything. Silkspan, AeroGloss,
and Dulux gave way to Hobbypoxy and later
MonoKote as the preferred method of
covering, and finishing a model … ahh, those
were the “good ole days.”
Advances in technology have been
nothing short of miraculous. We live in an era
unsurpassed by any other in terms of our
access to new technologies to benefit
aeromodelers.
Unfortunately, in addition to the
advantages of new technology, it can create a
few problems. Throughout the years we have
dealt with a few health hazards.
Tetranitromethane comes to mind—not to be
confused with nitromethane—as well as
some composite materials such as boron.
New technology deserves attention to the
difficulties it presents as well as the
opportunities it gives us. Nowhere is this
more apparent than in the recent advances in
battery technology.
The development of high-tech batteries
has enabled aeromodelers to enjoy many
activities that would have been unheard of
five years ago. The power density of these
batteries has allowed electric models to begin
to rival gas models in performance and
duration.
Smaller, lighter batteries for flight packs
in our radios allow us to fly smaller models
and enable us to increase the control features
in larger models without the associated
Dave Brown AMA president
President’s Perspective
June 2004 5
Safety should
be paramount in
anything we do ...
Dave Brown
AMA president
[email protected]
When Lithium cells explode, they create a
fireball. The cell itself is highly flammable
and will ignite anything combustible around it.
This can happen when the battery receives
physical damage such as in a crash, but it
seems to be the most common when the cells
are improperly charged. Hooking up the
wrong charger or setting the charger
improperly seem to be the most frequent
causes I have heard of.
Research on the Internet provides
information about the dangers of these cells as
well as accounts of incidents. To date, there
appears to have been more than 50 serious
incidents among modelers, so this problem is
severe.
The AMA Safety Committee is looking
into dealing with this danger. I’ll share a few
ideas I have heard for you to consider if using
these batteries and you can expect more
information to be provided in the future.
Education is the secret to handling any
new technology, so do as much research as
you can before using Lithium cells. Some
“experts” recommend that you isolate the
batteries outside of your house or car when
charging, or at least place them in a fireproof
container while charging.
If the cells show any sign of swelling,
immediately get them outside and away from
everything and leave them there. I’ve heard of
batteries erupting into a fireball as much as
two hours after they have been taken off the
charger because they started to swell.
Li-Poly batteries seem to be more critical
than Li-Ion, so use more care in their use.
Only use the charger specified for the battery
you have, and if it is adjustable in any way
(such as number of cells), be careful to set it
properly.
In short, be careful! This technology
can be a great advancement for our sport,
but it deserves your complete attention
when using it.
Some manufacturers have incorporated
circuitry into the cells that prevent the
overcharging problems, but this is not
universally implemented. I’d certainly look
for similar protective devices in the batteries I
purchased.
I strongly recommend that you research
how these batteries work before you use them.
Safety should be paramount in anything we
do, and education is the root of most safety
programs.
Look for more information about this
subject to come out of the AMA Safety
Committee. MA
06sig1.QXD 3/25/04 9:27 am Page 5
Edition: Model Aviation - 2004/06
Page Numbers: 5
