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Old Aug 11, 2004, 03:55 PM
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Tom,

Your pack isn't all that big - assuming rated capacity and substantally full charge, about 8 watt hours.

Drop it in a bucket of salt water out in the back yard for a day or two.

Assuming it could start out discharging at a 5c rate (I doubt it could do even that through salt water) - that's only 40 watts. It's not going to hurt anything out in your back yard.

- RD
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Old Aug 11, 2004, 05:14 PM
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Quote;There is risk with every power source. LiPo's have some as well as others.

I have never heard of a LiPo accident where there wasn,t operator error, maybe there is , butI haven't heard it.
I dont know about you all but I make mistakes (though rarely) and I would hate to lose my house, field privleges, or Life. too a fire . you cant with a honest out look compare the dangers of Lipos to Nicads or Nimh cells. and as your Lipos get older more damaged and fall in the hands of some ones Kid brother .these are going to bite us in the AS#. Cheers Mike B.
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Old Aug 11, 2004, 05:34 PM
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Wingman33;

Lot of smart guys out there sell their
well used old packs still in working condition
very cheap.
Others, even more generous, just give them away.
These people know what they are doing, they get
rid of the problem before the "you know what"

Folks, be warned, do not buy well used Lipos, you
buy problem then. Old lipos are prone to troubles.
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Old Aug 11, 2004, 05:54 PM
kit
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It's just amazing that anyone with an IQ higher than a sump pump would think that a solution of salt water is a short or "dead short", when the resistance of salt in water is in the 100's to 1000's of ohms and will never draw a 5C rate from a pack....and Yes, a pack of lipos will sink to the Bottom of a container of salt water. How people come up this nonsense is unreal.
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Old Aug 11, 2004, 06:10 PM
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I hooked up a 10V 25w tail lite bulb to a 1020 2s1p and got one cell to 0V overnite, the other cell was at 1.5v .
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Old Aug 11, 2004, 06:16 PM
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I got a used TP 1320 10c pack only 3 weeks old for $20. The only problem was a loose battery lead and broken tab, repairable. Fixed, flies like any other brand new 1320 TP LIPO. The previous owner was pulling too hard on the battery lead and did not know how to fix it or maybe too lazy.
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Old Aug 11, 2004, 07:51 PM
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Sunnyvale Ca
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what happens when you go on vacation????

LiPoly users,

I go on vacation for 1.5 weeks and the battery world falls apart. Just what is going on here?

FREEFLYER: just so I can be sure: the ballooned pack was under salt water for about 30 seconds before you saw flame (what color?) coming out of the pack? And the black/gray soot came out also and rose to the surface?

I am really amazed. I think there is like 1-2 grams of Li in the 3S1P pack and would be amazed if .5 gram of it were pure Li if it got plated out of the LiCo mixture. This really sounds like an experiment I will have to attempt to replicated (which Mr. Murphy will almost assuredly guarentee that I will not be able to reproduce). I know that Li burns in the presence of O2, but would it burn under water? Maybe there is enough O2 in the electrolyte to complete the reaction.

By the way, I think you did all the right things. I would have used sand instead of H20, but water is far more preferrable to nothing at all. And your quick thinking to put all that together in the short time is really commendable. Most of the flyers I know what be thinking: "How can I save those expensive Dean's Ultra plugs before the pack goes?" Just imagine what that would have looked like if you have a 6S3C pack on your hands.

SO HERE IS THE EXPERIMENT:
I will find a 3S1P pack and put it in a ziplock bag. I will RTV the test leads to the sack and get as much air out of the sack as possible (otherwise I will be charging under water). I will weight the pack down to be sure it will go into at least 6" of water. I will use an old fish tank (with fish removed) to hold the water. I will do my usual "overvoltage" setup to cause it to go thermal. I think I will overcharge it outside the water to get the pack hot (like 80 deg C), then I will put it in the H20. I fear the water will cool the reaction and stop thermal runaway, but who knows. It will be very interesting to see if it "burns" underwater. Anyone see any problems with this setup?

RCGUY01:
remember that all pioneers wear "arrow shirts". Those of us who tried Lipoly early are pioneers. Most of us try to use kevlar under those "arrow shirts" to give us some protection from the Indians, but you can never be sure. I don't think that LiPoly is for a first time flyer. I think you have to have at least a year of NiMh under your belt. This helps keep the Lipoly out of early crash situations also. But I think you have to RELIGIOUSLY do the safety things. I get sloppy sometimes and have been lucky. But now I charge in the pyrex pans and am starting to use the metal tubes to separate packs. I am hoping the new chemistry will come to market soon and make this a safer place for all of us. I have only one NiMh any more (for a Zagi) and all the others are LiPoly. I could not fly the little planes if it were not for LiPoly. So it is a question of risks and rewards. And I really like the rewards.

SHARKSTOOTH:
most of the problems are "pilot error", but there are cases where the LiPoly have "gone south" all by themselves. So even more care must be taken. When I was a kid, I used to take my father's 30-06 shells apart to make rocket fuel.....every once in a while, the bullet would go off while I was removing the slug.....you have to say out of the projected path! The same is true for LiPoly: hope for the best, plan for the worst. Get those sand bags beside your charging station. Charge only a few at a time. Always feel for heat or something strange every 10-15 minutes. Don't leave the area but for a few seconds at a time. Transport in safe containers. I am willing to go through all these constraints to get the rewards.

THOMASJOEHNK:
could you please describe how long each cell "burned" before the next cell in the pack went thermal? We have had one case here of a large pack go up and I am trying to estimate how long the entire pack can make a "fireball" that puts everything around it in danger. Please describe everything you can about the pack and its changes before the first outbreak of fire. Thanks.

GENERAL:
I am "gravitating" towards the direction advocated by RD Blakeslee. We need to charge parallel and reconnect serial. This seems to have the least problems....aside from having big connection blocks to put the batteries back together in the xSyP configuration. But at a minimum, I think checking the individual cell balance every 5-10 charges is the "right thing to do". I am making up a pair of multimeter clip leads to do this now. very sharp pins soldered to aligator clips seem like the right way to go. I will let you know how this works over the long term.

I would say that cell imbalance because of overdischarge will turn out to be the "Lord Valdemore"(Harry Potter reference) of the problems with Lipoly swelling.

I took a MSW and a SMK-like EPP plane with me in my motorhome while on vacation. I flew in Portland and Seattle on my trip. I used my Triton to charge my Lipoly while I was driving. I charged inside my big metal tube with a nomex sock over the end. It sat on the driver's console while charging and I could feel it every 5 minutes to see if it were hot. I kept thinking about how I would "eject" it if it went thermal. My best solution was to grab the tube, yank the banana plugs free from the Triton, and chuck the assembly out the driver's window. Can you imagine the look on the semi-truck driver's face to see a flaming Lipoly firmly attached to his radiator as he whizes past me? OK, so I will have to do a "hook shot" and chuck the assembly over the motorhome onto the passenger's side. It would be the "environmentally friendly" thing to do.
Crazy Ted -- living up to his name
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Old Aug 11, 2004, 07:54 PM
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Quote:
Originally Posted by kit
....and Yes, a pack of lipos will sink to the Bottom of a container of salt water. How people come up this nonsense is unreal.
Actually, Kit, if it's puffed up, it may not.

If the density of the puffed pack is less than the density of an equal volume of saltwater, the pack will float.

- RD
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Old Aug 11, 2004, 08:10 PM
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Quote:but there are cases where the LiPoly have "gone south" all by themselves. So even more care must be taken. When I was a kid, I used to take my father's 30-06 shells apart to make rocket fuel.....every once in a while, the bullet would go off while I was removing the slug.....you have to say out of the projected path! The same is true for LiPoly: hope for the best, plan for the worst. )) This stuff is great put a grin on me. but you know what Im getting at your wife is going to sell one of your old packs in 5 years in her garage sale to the 10 year old kid down the street,hes going to plug it into his big brothers old Astro charger Burn his house down and his Uncle the crack Lawyer is going to sue your ass off and win Cheers mike B.
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Old Aug 11, 2004, 08:23 PM
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Quote:
Originally Posted by kit

and Yes, a pack of lipos will sink to the Bottom of a container of salt water. How people come up this nonsense is unreal.
hmmmmm, does that include ballooned packs?
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Old Aug 11, 2004, 08:50 PM
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Quote:
Originally Posted by kit
Yes, a pack of lipos will sink to the Bottom of a container of salt water. How people come up this nonsense is unreal.
So you've replicated the incident and can say without any doubt that there's no chance that a catastrophically failing pack might come to the surface, perhaps in a ballooned state as RD and Hoppy suggest, or perhaps due to superheated water currents?
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Old Aug 11, 2004, 09:24 PM
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It's VERY possible a puffed pack could come to the surface! I'm not saying that it's a guarantee, but I do have a hypothesis as to why this may take place if it indeed does. The gas that is produced in a puffed Lithium polymer pack is Hydrogen. A hydrogen filled polymer balloon could very well make it to the surface if there were sufficient hydrogen to overcome the weight of the 'wafer' in there.

As far as "who comes up with this stuff", I believe the guy that had the incident did! Maybe he just made all that up...yeah, that's it...rrrrrright. Ever heard of a thing called BUOYANCY kit?!?
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Old Aug 11, 2004, 09:50 PM
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Wingman33 :

Come on over to the field at Schiller Park sometime and fly, I am the safety officer there.

We fly every day, weather permitting. I agree sooner or later these batteries are going to be featured on 60 minutes. All it takes is a few bad accidents and someone to report on it.

I pledge to make sure mine are disposed of properly. I will burn them in the fire pit up at the farm , under a close watch.

An inadvertant use by an uninitiated or informed person who happens upon them could be quite tragic. We need to be so careful.

Someone should publish pictures of a Pyrex Sand setup and make it mandatory handout with every LiPo sale. Or something to that effect. I have a stack of warnings that came with my Triton and additional handouts from Troy at Bishop Power Products, and I also have the AMA LiPo warning. Pictures of the Pyrex Sand setup would have fit right in.
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Old Aug 11, 2004, 09:56 PM
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Still no answer to my question of how to dispose of this 3 cell pack of mine with the wires cut off at the covering. Too short to hook anything to to discharge, although they were only on the charger for 10 minutes before I felt the heat in the pack so I doubt they have very much in them. How about some help here. Tom
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Old Aug 11, 2004, 10:02 PM
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Quote:
Originally Posted by Tom Smith
Still no answer to my question of how to dispose of this 3 cell pack of mine with the wires cut off at the covering. Too short to hook anything to to discharge, although they were only on the charger for 10 minutes before I felt the heat in the pack so I doubt they have very much in them. How about some help here. Tom
Just drop the pack into some water to which you have added some salt and leave it there for several hours. The salt will raise the conductivity enough to slowly and completely discharge the pack.
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