Red Scholefield
Posts: 5594
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Joined: 12/8/2001
Last Login: 9/27/2009
From: Newberry, FL, USA
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quote:
ORIGINAL: J_R
Hi Red
Fred offered to post it on request. If you have the redline copy, why not post it?
OK, Here it is: Original in black, Dave's comments in red, Fred 's response in blue.
SOAPBOX: ELECTRIC FLIGHT AND THE FUTURE OF AMA
I feel it is necessary to correct what I feel is misinformation published in two editorial columns (“President’s Perspective,” Model Aviation, June, 2004 and August 2004) that-however well intentioned-is misleading. It was disappointing to see such information presented with no apparent evaluation of the information or time taken to understand the impact on the fastest growing and most important technology in AMA model activity; i.e., electric. The AMA is vitally concerned with the continued loss of flying sites because of noise and has been concerned for 40 years with the gradual growth in average age of its membership, i.e., the perennial “where are the juniors?” problem.
Electric airplane modeling has leaped forward from a very specialized activity that few cared to pursue because of limited performance to the point that Designer Scale/Team Scale at a number of key scale meets has been won by George Maiorana with a 30 pound 4-engine TU 4 bomber powered by Li Po packs and brushless motors. Electric models are now placing in world competition. Li Po battery technology has made it possible.
In the past two years, Li Po suppliers have jumped from one to at least 20 in the US and prices have dropped by 1/3. As of this summer (2004), brushless motors and the third generation high discharge rate Li Po packs can now be used to convert and power models that had been powered by 40 to 90 size glow engines. By the time this is published, a 3.2AH Li Po pack that can deliver over one horsepower in the same weight as a 16 ounce tank of fuel will be available. Cost of a tank of fuel: about $2.00. Cost per 100 flights: $200.00. Cost to recharge: about $0.10. Cost for 100 flights: $10.00. Time to refuel: about five minutes. Time to recharge, about 23 minutes. The wait for your turn at the pin: about 15 minutes. Time to wipe the oil off the model: about 20 minutes! No more oil soaked models.
No argument here, but, do you, really, think this is a good place to be trumpeting one form of modeling, over another?? I think this would be better, if the cost's were not addressed, OR were, fairly, addressed, including the "investment" expense in such motors, and batteries. I have a friend who is flying electric in F3A pattern, and he says the electric is slightly MORE expensive, even flying as much as he does. For the typical modeler who flies <100 flights/year, it's tough to make the economic point. The difference in OPERATING cost, in your example is $190 for 100 flts, but the battery cost is that much, or more, for anything, remotely, approaching a model which would use a 16oz tank, to say nothing of the motor, and charger. High performance electric flight is great, but it's hard to push it as an economic advantage.
That is your opinion Dave. I ran numbers with actual costs to present what I said. It is quite reasonable to assume a well cared for engine will run for 1,000 flights while a good brushless motor probably will last much longer. I did not take advantage of the latter but ascribed 1,000 flights life to each. We aren’t talking about the high end pattern competition model but rather switching the 10,000 to 1 sport modelers to electric. I recall very well the complaints that only the well heeled or company reps as you were could afford to fly the very specialized pattern models. Do you really think a 20 year old kid can shell out $3,000 for either type model and afford to spend every day practicing?
Properly handled, Li Po batteries are much safer than glow fuel and very much safer than gasoline.
Perhaps, true, AS QUALIFIED, but the problem is that many members were treating these batteries in the same way as they treated their Nicads, including the use of Ni-cad chargers. I read "advise" on the internet, which said to use your Ni-Cad charger, "the only reason the Mfgrs make special chargers, is to make money"
It has been our responsible position all along to have the modeler not treat the batteries loosely. You can always come up with an unsubstantiated “old wives tale” to support your position.
You wouldn’t place an open can of gasoline next to your furnace and we hope you won’t put Li Po batteries under charge on a box of balsa.
True, again, but how many modelers are used to charging their models with the battery inside? Few of the "toy" electric models require that the battery be removed for charging, nor do I remove the Lithium Cell from my phone to charge it.....why would it be so obvious this it unsafe in the case of our models??
Nonsense argument.
Electric modeling has been freed from the limits of small, hand-launched park flyers. Now, the beginner that AMA covets so much can purchase the ARF or kit trainer of his choice, charge the batteries, and, with minimal help, learn to fly without crashing.
What does this have to do with power source??
Has everything to do with getting and keeping beginners and the growth of AMA. Sorry that you fail top recognize this.
The most difficult task of all -- save learning to fly -- of getting a balky engine started, adjusting it, and flying it without burning it up with a lean run has been replaced by flipping a switch, advancing the throttle while a safe distance from the prop and taking off. Being able to pick up the clean, dry, oil-free airplane to go home is icing on the cake. The variety of scale electric models is endless. Little wonder new modelers are being attracted.
It behooves AMA leadership to recognize new technologies and utilize them to the fullest to return the AMA to the vibrant, hobby/sport that has so excited three generations since the AMA was formed. Slamming the technology that can make it so is not acceptable.
I do not believe that pointing out the safety concerns of a technology is "Slamming" it. My column didn't "SLAM" electric, my column pointed out the benefits, AND the risks, and emphasized the need to recognize those risks, in order to use that technology safely.
As I told you, we have record of about as many incidents with Ni Cd and Ni MH; yet you choose to single out Li Po to raise all the issues about. You do not understand that Li Po is the future of electyric and electric is the future of AMA.
If we all looked at it that way, we would still be trying to fly on five frequencies at 27 Mhz. Once involved, the electric modeler then has the option of moving through the ranks of all facets of modeling up to and including giant scale modeling.
First, let’s explain the difference between Lithium Ion and Lithium Polymer. The older Lithium Ion technology (circa 1991) requires these cells to be enclosed in sealed metal cans. If a Li Ion cell is electrically abused, pressure builds up in the can. It takes a lot of pressure for the can to relieve. That pressure can cause the can to explode violently. The over pressure occurs when the cell is subjected to over voltage during charge, by shorting the cell or from incineration.
This fails to mention that, typically, Li-on cells, typically, have vents, which prevent this pressure buildup. While these vents, occasionally will plug, and allow this pressure buildup, it isn't very common. An internal short, can cause ANY metal cased cell to "explode". In this sense, a ni-cad can be a problem, also.
Interesting: you never mentioned that in your column. Li Pos have vents too. They always unseal at the bottom of the envelope. They go Hissss when they vent; not a loud bang!
Lithium Polymer (LiPo®) technology was developed specifically to replace potentially explosive Li Ion.
My research would indicate that this was NOT the reason for LiPo developement. LiPo developement was driven by the need for smaller, lighter batteries (high power density), which would be integrated into electronic devices such as cell phones, which provide their own "protective" case, and internal charging circuits, with, proper, safegards.
You have merely displayed your ignorance of Li Ion/Li Po. Li Pos are only slightly lighter than Li Ion, although 3 to 5 times lighter than Ni Cd & Ni MH.
Contrary to Dave’s statement, LiPo® batteries are relatively tolerant of overcharge and do not vent until they have been charged at some 40% above the limit of 4.2V/cell for up to 20 minutes.
For people who are used to charging their ni-cads for long periods, this 20 min isn't very long, and using a Ni-cad charger, of unknown voltage isn't too smart, but was recommended by some, on the internet.
Don’t know what forum you read, but every forum on Batteries and Chargers carries repeated warnings to newbies not to charge using Ni Cd chargers. Every web site carrying Li Pos carries that warning. Every pack we sell has that warning. In recent times, every prop carries a warning that you can get hurt if you stick your hand in the prop; yet people still do so.
If abuse continues, the pouch ruptures at relatively low pressure. Under extreme conditions of overcharge, venting may be accompanied by flames. The release of pressure is a hiss, not a loud “Pop” like you get when a paper bag is popped. Venting occurs only after the cell has swelled by over 50% to create a “silver sausage” to warn you. Cells in metal cans don’t warn you before they explode!
That's great, if you know enough to remove the battery from the model for charging......some people didn't even know this, simple procedure. Cells in metal cans don't, normally, explode, unless the vent clogs. You seem to want to ignore the fact that LiOn's have vents.
Yes, and people still stick their hand in the prop every day. It is the canned cell that does not vent that explodes. How do you know which one? In the same fashion, we tell everyone that a Li Po can vent with flames, not that it will, it can. You missed the point that millions of devices in use with Li Ion do not explode; but they can.
What is important is that in the US, over the past two years, usage has grown to well over a million LiPo® cells in use in RC without protective circuit modules (PCMs). In those two years, LiPo® packs have been charged several million times. Out of those several million cycles, there have been some 20 to 50 reports of venting with flames- the precise number is not significant. There has been no bodily harm. That is a probability of roughly one in a million - miraculous in view of not having PCMs on the packs. No damage in any incident has been caused by a pressure wave that causes pressure impact- as defines an explosion- even one that took place adjacent to my clumsy hand that had just accidentally run a T-pin into a big 3.2 AH pack.
First fire you refer to, and that t-pin, probably wouldn't have penetrated a LiOn cell!Another danger point for all cells: Dr Keith Shaw tells me he regularly inspects all cells (Ni Cd and Ni MH) for dents and discards any that are dented. I can report personally that not even a hair on that hand was singed! LiPo® cells do not spontaneously catch fire during storage. The main concern is severe cell abuse and, even then, only in the presence of certain concentrations of moisture and oxygen. The main thing needed to handle LiPo® cells safely is to treat them as if something can happen and to act accordingly. We do not encourage people intentionally to cause cells to ignite for one common-sense reason: it happens only under narrow conditions. We know of several who have tried this and found that the cells did not ignite. This, in itself, leaves a false confidence that ignition never happens-and that is not good. We don’t say ignition will happen; rather, that it can.
As reported by incident observers, almost all LiPo® incidents were caused by incorrect charger cell count settings, and all are fully described in online forums. Of the reported incidents, all but one would have been prevented by use of the device known as Safety Guard or a stock PCM or cell balancer that will soon be commonplace. All can be prevented by use of the upcoming generation of charge control adapters/chargers during pack charge. The newest generation of automatic cell count detection chargers has a proper logic that is much safer than manual cell selection. It is easy to forget to reset a manual count.
Protective circuits prevent overvoltage when charging LiPo® packs with a current-regulated charger.
Assuming these are in place, this is true, as I pointed out in my article, but they are not, universally, in place. While these are becoming more common, there are still some, unprotected packs out there. The difficulty is that many modelers don't (or didn't) , know that these were important.
They have know that from the first information that I wrote, put on our web, and have posted regualrly on forums. Connected between charger and pack, if the protective circuits output voltage exceeds 4.2V/cell, it disconnects the pack or the individual cell from the charger-minimizing the chance of cell damage and dangerous conditions. A Protective Circuit Module (PCM) is used on every Li Ion pack.
Wouldn't this indicate that those cells are less likely to create a problem??? If we didn’t believe that, we wouldn’t be providing Safety Guard and introducing a new cell balancing charger momentarily. That done, Li Po s become as safe as any chemistry. We stll say to treat the cells as if something caould happen; same as we tell peopl not to store gasloline next to the furnace.
Versions of a cell balancer that can be connected across each cell in a pack will be available by the time this is printed. The cell balancer by-passes charge current around that cell as soon as 4.2V is reached across the cell. PCMs as such can not prevent cell unbalance; rather, they do prevent any cell in a pack from exceeding 4.2V. If a pack has a cell out of balance, that cell may never reach 4.2V but the “good” cells will and they must have charge terminated before they reach 4.2V. A cell balancer will cut off charge to the better cells as they reach 4.2V and continue to bring the low cell up to 4.2V. With the cell balancing charger, every cell in a pack is brought to perfect balance on each charge.
Without some way to access EACH CELLS charge status, there will always be the possibility of an overcharging problem being caused by unballanced cells. A device, which, simply, measures the voltage of the pack, without any way to determine individual cell status, does not cure the problem. However, it's cretainly, better than having no device at all.
With cell balancing, we access every cell node. No cell can ever exceed 4.2 V.
LiPo®-compatible Electronic Speed Controls (ESCs) prevent over-discharge by cutting motor power while maintaining receiver and servo operation. Normal PCMs remove all power, so they cannot be used in RC airplanes. An in-line cut off just introduced will permit use of Li Po with any ESC ever made.
There was one reported incident where a protective circuit or cut off of any type might not have worked. In this incident, a flyer crashed his model, but never took the pack out of the model to check it (so it’s unclear whether the wiring shorted or the pack was damaged). He laid the model in the back seat of his car, where the model caught fire and proceeded to burn an expensive luxury car like tinder. This makes one wonder about the safety of car interiors.
Fire two, referred to in this article, and exactly the type of situation I was referring to when I said that they could erupt into a fireball as much as 2 hours later. It is this type of incident which I was most concerned about, where a modeler, unknowingly, puts his property, or family at risk, as a result of not knowing the potential dangers of these batteries.You have it wrong. The guy knew he should have checked the pack, whether it was Ni Cd or Li Po and did not. No one can legislate against stupidity. You can’t be there to see to it that the guy does not set an open gas can next to the furnace either or fly a turbojet over a crowd at 200 mph. Your’s is a specious argument for the sake of arguing.
LiPo® handling, charging, use and disposal are thoroughly described at many web sites and forums. Similar precautions are required for NiCds, NiMHs, fuel, and turbine powered models. You wouldn’t stick your hand in a spinning prop. Likewise, treat your batteries with respect. Education and discipline are the keys.
Isn't this what I said in the next to last sentence of my article??
Gets lost in all the damage you did beforehand.
The most misleading statement in the President’s Perspective is that LiPo® chemistry is explosive and Li Ion is not.
Please show me where I said that????? The closest thing I said to this was "Lithium Polymer batteries seem to be more critical than Lithium Ion, so use more care in their use" In fact, I just used word search on my original column, and I didn't use the word "chemistry" anywhere.
You know what the word paraphrase is? You will note that there are no quotation marks around the statement. As explained above, this is just the opposite of the facts. That could really get someone hurt, as Li Ion cells absolutely must use a Protective Circuit Module (PCM) when charging. Use of the PCM is what makes them safe and mistakenly led the interpretation that Li Ion as a product is safer. Every cell phone next to your ear, every laptop or notebook computer, PDA, digital camera or the like has a PCM on the pack or on each cell in the pack for the reason that Li Ion cells can explode; not “do explode” - but “can explode.” If a manufacturer uses Li Ion without a PCM- look out, Many millions of Li Ion cells are used worldwide in consumer products. If even a few of these exploded, the media would quickly publicize the problem and manufacturers would issue recalls. We hear of many concerns for cancer possibly caused by radiation from cell phones, but never an exploding battery. That is because cell phones using Lithium cells are equipped with a PCM. Some two years ago, before LiPo® cells began to see widespread use, people were modifying Li Ion packs to remove the PCM so they could be used for model airplanes. We are indeed fortunate that no one was hurt by an explosion of those unprotected cells.
Since Li Ion cells are contained in sealed metal cans like NiCd and NiMH cells, they explode with great force. We recently received a report that a Li Ion cell exploded during a high overcharge test at a major testing lab. The cell destroyed a heavy plastic enclosure and cracked a concrete block wall. A LiPo® cell might vent under those circumstances and it might flame, but it does not explode and create such a pressure wave. The eruption and resultant flaming material is easily managed in a container such as a coffee can. A fireplace, oven, charcoal grill, a toolbox or a surplus ammo box make excellent charge safes. Even a sheet rock enclosure will work. You can place your hand on the backside of ½ inch sheet rock and direct a propane torch to the opposite side and not feel the heat.
How many modelers recognize the need for this type of precaution?? Prior to my article, I'll bet it would have been a VERY small percentage. Ironically, I STILL have modelers mocking such precaution as un-necessary.
You still insist on legislating intelligence. People can choose to ignore any part of the AMA Safety Code but we still have the safety code.
The AMA Safety Committee recently released an announcement regarding the possibility of fires from Lithium cells. While this announcement was being drafted, we had a lengthy discussion with Don Lowe, Chairman of the Committee. As a result, the Safety Committee’s announcement reflects a reasoned response to the situation. We endorse that announcement. Don and the Safety Committee are commended for taking a professional approach to handling the matter.
Ironically, I have had as many negative comments about that bulletin, as I have had about my column(s). It's interesting to see just how divergent the idea's of safety with these batteries are. Many condemn ANY idea that anything could be put in between the battery pack, and the charger to "cure" the problem. Most seem to believe the problem can, ONLY, be adequately addressed, with devices built into the pack to monitor each cell, yet, others, like yourself, seem to endorse the idea. The only thing which is consistent is that NONE of the experts advocate strapping a few cells together, and plugging them into "just any old" charger, yet, that is what, occasionally happens.
Ironically, I hear the same about any AMA Code or activity. I have learned to use a horse manure filter on most of that. I know every EXPERT in this field and have never, ever heard on advocate such action; quite the opposite. I sure don’t know where you get your experts. However, since you never talked to me about it and acknowledge that you “didn’t even know I was involved with Li Pos” it seems to me you are not the slightest in touch with the field and or electric flight.
In summary, 1.Education and careful attention by the vast majority of users for two years has prevented all but a handful of incidents. 2. Every incident reported was preventable simply by following the warnings on the cells/packs and presented in the web site of most cell
I'll feel better when this is ALL.
suppliers and 3. The new generation of accessories being introduced in 2004 will permit control of charge and discharge of LiPo® cells using proper protection during both charge and discharge that makes the LiPo® cells much safer
I agree, to this point. I'm not convinced that LiOn cells are any more "dangerous" that LiPo's.....just "different". Perhaps LiPo's don't "explode" it the technical sense of creating a pressure wave (it could be argued that that wave is, simply, at a lesser pressure), but they are more susceptable to physical damage, which can cause a short (things like T pins, for example). In the end, as I said in my article, "Properly used, either technology is, perfectly safe.".....sound familiar??In due time, I will demonstrate that very graphic difference to you and the Council. than Li Ion cells. The reason? Even if a LiPo® control circuit should fail, LiPo® will cause no harm at all if you just follow the guidance to treat the cells as if they could, not will, vent with flames.
I do not think there is anything to be gained by "slamming" one type of lithium cell, in order to enhance the other. It appears which is "better" in any, particular, "experts" opinion, is, largely based upon which ones he has for sale.
In spite of what I have pointed out above, which is reaction to your comparison of LiPo, to LiOn cells, I am NOT, a proponent of one, or the other. Based on what I know, I would, probably use LiPO cells, if I was to try an electric model, today. My comments are not intended to support EITHER technology, over the other, but, rather, to point out that I have been told that each has it's advantages, and disadvantages.
I based my column on the information I was able to obtain, in a few hours, on the internet, back in March of this year. I did NOT represent myself as an "Expert" on Lithium batteries (in fact, I specifically denied that). I, simply, reported to the members what I was able to obtain in information, after having this "problem" pointed out to me by another well known modeler. My goal was to make the members aware of the potential dangers, and encourage them to do some of their own research. Above all, encourage them to read anything which was supplied with any lithium battery which they bought. The original person who approached me on this subject (Gerry Nelson, at the AMA show in Calif) , was convinced that the LiPO's, were much more dangerous than the LiOn's, and, emphatically, told me so. My research into the subject, didn't seem to indicate that, but, it was underlying in my mind that this was possible. The incidents I learned of, primarily, involved LiPO's, but that could have been as a result of their being new, more so than them being more of a problem Upon further research, as well as some simple logical thinking, I determined that the risks were more "different" than one being more dangerous than the other. The practical fact is that it doesn't matter if the cells involved in an incident are LiPO, or LiOn. What matters is that the people need to be aware of the increased risk, compared with what they have become accustomed to, in order to take proper steps to protect themselves. While some cells may "explode", and others may "vent with flames", it is the ensuing fire that is the greatest concern, and the members needed to know that this was a possibility, in order to protect their property, and themselves. I could have waited until all of the "experts" agreed to a statement (might have happened in 2006!), but that could have resulted in more property destruction, and possibly, loss of life, while we tried to reach a concensus as to, exactly, what would be said. At the time I wrote that column, I gave the membership the best information I had available at the deadline for that column. If I was to write that column, today, I would have changed VERY little. I think the membership needed the warning in as quick a manner as possible. I think timeliness was, and is, FAR more important, than, absolute, technical accuracy, when those technical details have NOTHING to do with the threat.
I'm reminded of the govt authorities, who stood by arguing while houses were being destroyed, whether the winds were "tornadic" or not, in order to make the decision as to whether to sound the sirens. We will never know how many people lost their lives while THAT discussion took place. I don't know about you, but if my house was in the path of that "whatever", I sure would have wanted them to sound the alarm, first, and argue as to the technicalities, later. (mid 70's, Cincinnati Ohio, during the tornado's known later for the destruction of Xenia Ohio).
In any case, I would NOT recommend that you harp on the "venting with flames" argument, as It is, overwhelmingly the attitude, among those I have heard from, that that argument is a joke, and you would be ridiculed for it, and that wouldn't be fair to you.
Dave Brown
You would not be aware, of course, that venting with flames is the terminology used by the industry. You have made it clear that you don’t care what is fair so don’t add hypocracy to the mix. You have voiced your opinion on two occasions, one after I had given you better information than you had, and refused to correct your misinformation. Now, this is my opinion and I do not intend to change it. I suggest that you let it ride and not keep the argument rolling and damaging AMA just to press your point. Since you called me today and threatened to cause harm to my reputation if I did not modify my Soapbox article, I felt it necessary to expose that chicanery to the Executive Council Publications Committee, so have forwarded a copy to each with the suggestion that you be restrained from further such attacks. I believe that the AMA still operates as a democracy despite your effort to usurp my First Amendment rights.
FM
Best regards,
Fred Marks , AMA 1733
AMA Hall of Fame
AMA Distiguished Service Award
fred @fmadirect.com <mailto: fred @fmadirect.com>
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