President’s Perspective - 2004/06
Dave Brown, AMA president
Safety should be paramount in anything we do …
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 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 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.
Types of lithium batteries
- Nonrechargeable lithium AA batteries (commonly available at retail stores) — useful where other chemistries won’t work well, such as in very low temperatures.
- Rechargeable lithium packs used in laptops.
- Rechargeable cells used in many cellular telephones and personal digital assistants (PDAs).
- Rechargeable lithium types commonly available to hobbyists:
- Lithium‑Ion (Li‑Ion)
- Lithium‑Polymer (Li‑Poly)
Properly used, either rechargeable 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 Ni‑Cds, these will not tolerate overcharging and can 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. 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 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.
Recommendations and precautions
- Educate yourself: do as much research as you can before using lithium cells.
- Charge safely: some experts recommend isolating batteries outside of your house or car when charging, or at least placing them in a fireproof container while charging.
- Watch for swelling: if the cells show any sign of swelling, immediately get them outside, away from everything, and leave them there. Batteries have erupted into fireballs as much as two hours after being taken off the charger because they began to swell.
- Treat Li‑Poly with extra caution: Li‑Poly batteries seem to be more critical than Li‑Ion.
- Use the correct charger: only use the charger specified for the battery pack you have, and if it is adjustable (such as number of cells), be careful to set it properly.
- Prefer protected cells: some manufacturers incorporate circuitry into the cells that prevent overcharging problems, but this is not universally implemented. Look for protective devices in the batteries you purchase.
- In short: be careful. This technology can be a great advancement for our sport, but it deserves your complete attention when using it.
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.
Dave Brown AMA president [email protected]
Transcribed from original scans by AI. Minor OCR errors may remain.
