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Model Forum / Radio Controlled / Air Models / July 2006LiPoly fire
Ok, "splain this one to me. Bought a new. 2 cell 700 mah lithium Polymer battery pack yesterday. Along with a new charger. they were checked out on the system, and then put on the charger. Charger is FMA Direct LIPO-203. 220ma charge, till the charger quit charging (light went out), about 3 hours. Took them off the charger, set them on the counter. 2 hours later, we stuck them in the airplane-a "littlest Stick", and put the wing on. Barreries are just in the airplane, not connected to anything. Just setting there. 15 minutes later, smoke is pouring out of the fuselage. Batteries are STILL not connected to anything.except that all the insulation is melted off the things, and batteries are swolen up like to Nicad size. Big mess. May have gorren so hot as to melt the reciever. Any ideas? If these things are THAT dangerous, maybe we need a different power supply. Roger > Ok, > "splain this one to me. [quoted text clipped - 13 lines] > Any ideas? If these things are THAT dangerous, maybe we need a different > power supply. Overheating in the sun, or previously overcharged/overheated. Once the pack swells up, it can get progressively likely to short internally. Some newer packs seem more prone to this. Undoubtedly it would be nice to have a power supply that didn't do this. Do you leave glo fuel canisters in the sun too? > Roger Not usually. However, the jug just swells a little. No fires. John VB > Do you leave glo fuel canisters in the sun too? > > > Roger Yes, I have left glow fuel canisters in the sun on many occasions. No one I have known or flown with has ever experienced a fire because of it. And, the heat in Arizona is FAR higher than in the UK. If LiPos will melt my electrics merely by sitting in the sun, then I will look elsewhere. -- Paul McIntosh http://www.rc-bearings.com > > Ok, > > "splain this one to me. [quoted text clipped - 23 lines] > > > Roger atta boy, nP Where, in my missive, did "hot" or "out in the sun" occur? This was all indoors. Idjut Limey! :-D Roger >> Ok, >> "splain this one to me. [quoted text clipped - 23 lines] > >> Roger > atta boy, nP > Where, in my missive, did "hot" or "out in the sun" occur? > This was all indoors. > Idjut Limey! :-D Try reading, and understanding the nature of the word OR...as in 'or previously overcharged/overheated.' Fuckin merkin. :-) > Roger > [quoted text clipped - 25 lines] >> >>> Roger Again, " Bought a new. 2 cell 700 mah lithium Polymer battery pack yesterday. New. As in never before used. factory fresh. spanking. NIB. Roger >> atta boy, nP >> Where, in my missive, did "hot" or "out in the sun" occur? [quoted text clipped - 35 lines] >>> >>>> Roger Roger, You were right the first time. Give up on D.H. he is probably too drunk to understand the FACTS you posted. Then he has to show his bad attitude about everyone in the world. > Again, > " Bought a new. 2 cell 700 mah lithium Polymer battery pack yesterday. [quoted text clipped - 40 lines] > >>> > >>>> Roger > Roger, > You were right the first time. Give up on D.H. he is probably too drunk to > understand the FACTS you posted. Then he has to show his bad attitude about > everyone in the world. It is not always effective to judge everyine by your own stanrdas. Just because you are high by six o clock every night, does not mean that the rest of the world has to be the same. This failure to move beyond childish solipsitic fantasies is known as 'ego centricity' - the feeling that you alone are representative of the world at large. Its a Merkin thing. another possibility is a bad solder joint in the battery pack. I've read some reports of extremely poor solder jobs on ready-made packs, waiting for the short to happen. I cannot tell if this is the case, but that is one possibility. It might be a good idea to make the lithium packs yourself, that way you could wire them for "serial use, parallel charge" (bring each termina of each cell to the connector, and have special connectors foo flight and charge that re-organize the pack. Parallel charging of a lithium pack is a good idea, as it automatically balances the back, which should be done after every 3rd to 5th charge anyway. -Tapio- Would like to see a diagram of this "serial use- parallel charge" wiring.!!! V > another possibility is a bad solder joint in the battery pack. I've read > some reports of extremely poor solder jobs on ready-made packs, waiting for [quoted text clipped - 9 lines] > > -Tapio- > Would like to see a diagram of this "serial use- parallel charge" > wiring.!!! Its possible. You need twice as many connector pins as there are serial cells. One harness wires the cells in parallel for charging, the other in the plane in series. Its not a perfect solution, because shorting cells at potentially slightly different levels of discharge can overheat them as well... But they will all end up at the same state of charge. > V > [quoted text clipped - 35 lines] >> >>-Tapio- :> Would like to see a diagram of this "serial use- parallel charge" :> wiring.!!! : Its possible. You need twice as many connector pins as there are serial : cells. Precisely. : One harness wires the cells in parallel for charging, the other in the : plane in series. : Its not a perfect solution, because shorting cells at potentially : slightly different levels of discharge can overheat them as well... But if you parallel-charge them every time they are darn likely to be on the same level of discharge every time you start charging... -Tapio- > :> Would like to see a diagram of this "serial use- parallel charge" > :> wiring.!!! [quoted text clipped - 12 lines] > But if you parallel-charge them every time they are darn likely to be on the > same level of discharge every time you start charging... No. That would imply that they are all *exactly* equal capacity. No two cells are exactly alike. One could equally well argue that, if you make up your pack with exactly equally charged cells (but of slightly different capacities) to start with, then after discharging, no matter what their end point voltages individually are, once charged up in series with exactly the same amount going into each as has been taken out, they will all end up at the same voltage fully charged. Which is, in fact, more ore less why series charging does not blow every pack up every time its used. The devil is, as always, in the detail. Parallel charging SOUNDS like a good idea to the simple minded. Investigation of it shows it has as many flaws as series charging. Ultimately cell voltage clamps and series charging is the way to go, or INDIVIDUAL charging of cells one by ne to restore balance - but if balance has been badly lost in a series pack, one should probably investigate why. It may well be the first sign the pack is on its last legs. Many of the problems being experienced are actually problems of MARKETING. Packs are sold as '1000mA/h 10C discharge' but in reality, whilst they may do that under carefully controlled tests, once, they are liable to fail dramatically if exposed to it on a regular basis. I use half the current draw and half the capacity that the marketing alleges is safe. I haven't had any problems so far. LIPOS have so much more power to weight and duration that I actually need, that there seems no point in pushing them to the limits. > -Tapio- | Parallel charging SOUNDS like a good idea to the simple minded. It sounds like a fine idea to those not so simple minded too ... | Investigation of it shows it has as many flaws as series charging. Really? I only see one big flaw -- when you hook the batteries up in parallel, if there is any signifigant voltage difference between the cells a possibly large current will flow until the voltages match. As long as the cells are fairly close in charge level this shouldn't be a big problem. You could also put some <1 ohm resistors in your charging harness to keep the currents down between cells, but they'd also slow down your charging rates. Remember, we're talking about LiPo charging, not NiCd or NiMH. | Ultimately cell voltage clamps and series charging is the way to go, | or INDIVIDUAL charging of cells one by ne to restore balance - but | if balance has been badly lost in a series pack, one should probably | investigate why. It may well be the first sign the pack is on its | last legs. I can see where measuring individual cells from time to time after a flight to determine how discharged they are is a good thing, but for normal charging after each flight, I see no problem with charging in parallel most of the time. Certainly, charging in parallel every time is better than charging in series every time and never checking individual cells (which is a much more likely scenario, since many (most?) packs don't even include the connectors needed to measure individual cells.) | Many of the problems being experienced are actually problems of | MARKETING. Packs are sold as '1000mA/h 10C discharge' but in reality, | whilst they may do that under carefully controlled tests, once, they are | liable to fail dramatically if exposed to it on a regular basis. I've got some Tanic/iRate 2200 mAh 10C discharge packs, and they do seem to handle 22 amp discharges with no problems. I don't fly wide open throttle (WOT) all the time, but for sixty seconds or so it seems fine. I've got hundreds of flights on them now, and I usually do at least 60-120 seconds of WOT flight each flight. Often I fly the plane (Combat Wings XE2) as a glider, and so my flights are 30 seconds of WOT, 5 minutes of gliding, 30 seconds of WOT, 10 minutes of gliding, etc. until either the batteries or I get tired. I've used my Astroflight Whattmeter to measure the current used -- on the ground, with my 3 cell pack and Astroflight 020, it'll use about 23 amps at full throttle. It should be a bit less in flight, but still fairly close to the advertised limit. | I use half the current draw and half the capacity that the marketing | alleges is safe. I haven't had any problems so far. They probably do last longer if you don't push 'em ... | LIPOS have so much more power to weight and duration that I actually | need, that there seems no point in pushing them to the limits. Depends on what you're after. Certainly, I prefer not fly at WOT for long -- I don't want to ruin my $75 pack. But so far they're doing what they were promised to do with no problems.  SignatureDoug McLaren, dougmc@frenzy.com People don't usually make the same mistake twice -- they make it three times, four time, five times... I have 10 Li Poly 1500 ma packs that are going in a pattern plane. Five are 7.4 volts , 5 are 11.1 volts. I plan on wiring one 7.4 and one 11.1 in series to attain 18.5 volts ,make 5 packs this way and then wire the five in parallel to get 7500 ma. These will be hard wired together terminating into one Deans ultra connector. I have an Astro Flight 109 D and that will charge everything at once. Have any of you wired this many this way ? Have you encountered any problems charging ? Thanks Ken Day >> Would like to see a diagram of this "serial use- parallel charge" >> wiring.!!! [quoted text clipped - 49 lines] >>> >>>-Tapio- > I have 10 Li Poly 1500 ma packs that are going in a pattern plane. > Five are 7.4 volts , 5 are 11.1 volts. I plan on wiring one 7.4 and [quoted text clipped - 8 lines] > > Ken Day Ken: take that question over to the ezone - www.ezonemag.com, and ask in the discussion forum on 'batteries and chargers' It sound's to me that you haven't been there. Trust me, and go. There is no quick answer, except to say that you are playing with fire, literally, and although at a glance I think it should work,at least for a while, I would much rather you were TOTALLY aware of the potential problems and how to anticipate them. : Have any of you wired this many this way ? Have you encountered any : problems charging ? Have not wired anything more than 3 series 1 parallel myself, but I've seen how some big boys do their stuff, and they seem to have all the cells parallel while charging. The reason is that every time you have cells in series while charging (and you plan to have 5, right), you run into risk of unbalance, overheating and fire. So if you plan to charge the pack in it's flight configuration be prepared too check the balance of each (sub)pack before each charge, and balance them anyway every third charge or so (by individually/parallel charging). HAving said that, ezone would indeed be a good place to discuss there matters, with people with first-hand experience. -Tapio- >: Have any of you wired this many this way ? Have you encountered any >: problems charging ? [quoted text clipped - 10 lines] > >-Tapio- Thanks. I appreciate your help. Ken > Ok, > "splain this one to me. [quoted text clipped - 13 lines] > Any ideas? If these things are THAT dangerous, maybe we need a different > power supply. What brand of batteries? BobbyG They are Kokam USA, marketed/distributed by FMA Direct. > What brand of batteries? > > BobbyG Can someone please tell me why we never have a problem with cell phon batteries that are lipos or liions but there is such a problem with th use of those batteries in our planes?? IE, why do they never explode i cell phones or in the charging process but we lose so many batterie due to fires while charging them for r/c aplications?? Thanks! -- WingsofEagle there are a couple of possible explanations, One of which is that most cell phones etc operate on ONE cell LiPo or Li-Ion batteries. If there is only one cell, there is no chance of imbalance between cells causing problems. In addition, Most of these devices use a relatively gentle charge and discharge curve where we DO tend to push the batteries in our planes to and beyond the limits of the technology. The more likely explanation is that LiPo fires relative to RC equipment tend to be over-reported, and other types of incidents involving the batteries tend to be ignored. There HAVE been occasional reports of cell phone batteries having problems >Can someone please tell me why we never have a problem with cell phone >batteries that are lipos or liions but there is such a problem with the [quoted text clipped - 3 lines] > >Thanks!! > Can someone please tell me why we never have a problem with cell phone > batteries that are lipos or liions but there is such a problem with the [quoted text clipped - 3 lines] > > Thanks!! Largely because the charge/discharge is electronically controlled to stay within limits which are far more conservative than those used flying a plane. Those of us whop never use LIPOS at more than about 65% of ratings are rewarded with long service life and zero fires. A F1 engine lasts about 800 miles before its toast, too..their tyres do at best about 100 miles. I have 53000 miles on a Diesel Landrover..the engine is barely run in and I have just put new tyres on the front wheels..the first ever. Go figure. Simply because of all the protective circuitry built into those units. An example of just how much was shown in Model Aviation a few months ago. Cheers -- \_________Lyman Slack________/ \_______Flying Gators R/C___/ \_____AMA 6430 LM____ / \___Gainesville FL_____/ Visit my Web Site at www.LymanSlack.com > Can someone please tell me why we never have a problem with cell phone > batteries that are lipos or liions but there is such a problem with the [quoted text clipped - 3 lines] > > Thanks!! >Simply because of all the protective circuitry built into those units. An >example of just how much was shown in Model Aviation a few months ago. Yep, I think you are on to one of the best reasons, Lyman. Besides having the charge protective circuitry built into the battery packs (where they can't be bypassed due to neglect or intentionally), the chargers are single-purpose and matched to the specific packs. No user controls subject to human error. That's the other best reason they have fewer accidents. Abel >Can someone please tell me why we never have a problem with cell phone >batteries that are lipos or liions but there is such a problem with the >use of those batteries in our planes?? IE, why do they never explode in >cell phones or in the charging process but we lose so many batteries >due to fires while charging them for r/c aplications?? When we start souping up our cell phones so they put out 30 amps, and re-charge in 60 minutes, we will see more cell phone fires. Hey, maybe I'm on to something. :) SignatureBob >>Can someone please tell me why we never have a problem with cell phone >>batteries that are lipos or liions but there is such a problem with the [quoted text clipped - 5 lines] >re-charge in 60 minutes, we will see more cell phone fires. Hey, maybe I'm >on to something. :) Hi Bob, long time no see! Dunno about hot rodding cell phones. If I could by doing so make one that could fry the ear hairs of the idiot driving 30 mph in the fast lane 'cause he won't shut and drive, I would. Maybe you ARE onto sumtin.' Not here yet for blaster cell phones, but souped up power tools with LiIon packs providing the energy are, and they operate at the kind of industrial strength levels of which you speak. LiPos developed for them may be our next generation of motivation - but DeWalt and Milwalkee et al are gobbling up all the production right now. Abel I'm presently testing samples of 2300 mAh packs from A123 Systems, flying them in a 4S2P configuration in a Telemaster Electro w/ AXI 2826-12 swinging APC 13 X 6.5. If these things come anywhere close to the 1000 cycle life they are advertising, they will bring a whole new era to electric flight. For information see http://www.a123systems.com/html/home.html SignatureRed S. Red's R/C Battery Clinic http://www.rcbatteryclinic.com Check us out for "revolting" information. > Not here yet for blaster cell phones, but souped up power tools with > LiIon packs providing the energy are, and they operate at the kind of [quoted text clipped - 3 lines] > > Abel >I'm presently testing samples of 2300 mAh packs from A123 Systems, flying >them in a 4S2P configuration in a Telemaster Electro w/ AXI 2826-12 swinging >APC 13 X 6.5. If these things come anywhere close to the 1000 cycle life >they are advertising, they will bring a whole new era to electric flight. > >For information see http://www.a123systems.com/html/home.html Glad you're looking at them, Red. Looking forward to your report. Abel I cannot find any dimensions on their site. Anyone? >>I'm presently testing samples of 2300 mAh packs from A123 Systems, flying >>them in a 4S2P configuration in a Telemaster Electro w/ AXI 2826-12 [quoted text clipped - 7 lines] > > Abel > I cannot find any dimensions on their site. > Anyone? [quoted text clipped - 9 lines] >> >> Abel http://www.a123systems.com/html/products/ANR26650M1specs.pdf 65mm X 26mm 70grams 70amp discharge continuous Red, what are you using to charge them? I have two developer packs also. You told me a normal lipoly charger can't be used. Is it the voltage issue? I'd like to DO something with the cells I have! Jim > I'm presently testing samples of 2300 mAh packs from A123 Systems, flying > them in a 4S2P configuration in a Telemaster Electro w/ AXI 2826-12 [quoted text clipped - 11 lines] >> >> Abel | >When we start souping up our cell phones so they put out 30 amps, and | >re-charge in 60 minutes, we will see more cell phone fires. Hey, maybe I'm | >on to something. :) Actually, my cell phone charges in a little over an hour. It's not quite 1C, but close. ... of course, people are now charging LiPos at 2-4C now. Personally, I'll stick to 1C for a while. | Not here yet for blaster cell phones, but souped up power tools with | LiIon packs providing the energy are, and they operate at the kind of | industrial strength levels of which you speak. They also weigh more ... | LiPos developed for them may be our next generation of motivation - | but DeWalt and Milwalkee et al are gobbling up all the production | right now. ... and we're gobbling them up. People are buying the Milwalkee 7s packs for about $105 on Ebay and pulling out the cells. It's about 1/2 to 1/3rd the cost of equivilent R/C packs, and can do 15-20C or so. They do weigh a bit more, but not too much. SignatureDoug McLaren, dougmc@frenzied.us "They say that absence makes the heart grow fungus." - the BareNaked Ladies |
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