Espritmodel.com Telemetry Radio
Reply
Thread Tools
Old Aug 10, 2004, 11:47 AM
Registered User
Walled Lake, MI, USA
Joined Feb 2000
11,182 Posts
Quote:
Originally Posted by raptor22
I was arguing could happen that a while back. Elemental lithium burns like hell (hotter than magnesium), and burns alot faster under water. But everyone says "no, its only a lithium compound". Well, why does it burn white then? The anion is Li!
There are no deep, dark secrets here. Manufacturers are required by law to state exactly what chemicals are included in cells sold to the public. All Li-poly manufacturers are consistent in showing no Li metal in the cells.
Dave Hederich is offline Find More Posts by Dave Hederich
Reply With Quote
Sign up now
to remove ads between posts
Old Aug 10, 2004, 04:49 PM
kit
Registered User
USA
Joined Oct 2001
695 Posts
Quote:
Originally Posted by Dave Hederich
There are no deep, dark secrets here. Manufacturers are required by law to state exactly what chemicals are included in cells sold to the public. All Li-poly manufacturers are consistent in showing no Li metal in the cells.
Dave, are you a lipo chemistry expert? Do you know about all the chemical reactions that take place inside a lipo? If you aren't, and you don't, then those reactions are "deep, dark secrets" for you, aren't they? However, if you are a lipo chemistry expert, then please explain to us what happens inside the lipo cell in the case of an overcharge condition.

Since you also seem to be an expert as to what "manufacturers are required by law" to state about their cells, are they only required to state the chemicals in the cells at the time of manufacture or are they also required to state any chemicals that may occur from unusual reactions inside the cell that may be present due to conditions such as overcharge, where elemental Li may be plated out?

Again, if you are an expert in MSDS statements, then please let us all know what exactly needs to be included by the manufacturer.
kit is offline Find More Posts by kit
Reply With Quote
Old Aug 10, 2004, 05:27 PM
one game away...
PerfectStranger's Avatar
Willoughby, Ohio
Joined Apr 2004
3,891 Posts
wow....i feel the heat, and it's not from the runaway lipo pack!!!!
PerfectStranger is offline Find More Posts by PerfectStranger
Reply With Quote
Old Aug 10, 2004, 05:53 PM
Registered User
United States, SC, Irmo
Joined Jul 2004
2,102 Posts
That was a better location to have a fire than a 17 year old Cleveland Oh girl had about 2 weeks ago. Her hip pocket. The pictures of what was left of the cell phone weren't pretty. The phone is history. The reporter noted that there was nothing left of the battery. She got off with only light burns, the "Treated and Released" type. Any battery is safe until abused. Some battery chemistry is more fragile than others. Don't get complacent.
50+AirYears is offline Find More Posts by 50+AirYears
Reply With Quote
Old Aug 10, 2004, 06:15 PM
Permanently Banned
San Jose Ca / RSA flyer
Joined May 2003
8,030 Posts
Kit

Check out www.bayrc.com battery forum Ted Cooper knows about LIPO chemistry down to the last atom, I think, he is a battery junkie, blows them up on a regular basis for destructive testing id IS TJ COOPER
hall woo is offline Find More Posts by hall woo
Reply With Quote
Old Aug 10, 2004, 06:51 PM
Registered User
Deer Park, Tx, USA
Joined Feb 2001
422 Posts
Well, I was close to jumping into the LiPo club until saw this thread. Every time I start thinking about converting to LiPo, see another instance of disaster(s) caused by a hobby. I guess will continue to live with the old fashioned nimh ( or even nicd ). I know can still set house on fire with those, but evidently not quite as easily. One mistake resulting in half the house burning down is too severe consequence for sake of a hobby.

As an aside, I saw something recently about Lithium Phosphate technology that evidently isn't as dangerous as LiPo. Guess I'll try my best to wait.
Russell2 is offline Find More Posts by Russell2
Reply With Quote
Old Aug 10, 2004, 07:01 PM
Permanently Banned
San Jose Ca / RSA flyer
Joined May 2003
8,030 Posts
Russell

Get a Tiger Moth that can run 45 minutes on a 2 cell LI-ION pack with qualcomm charger. This a safe system because there is a safety circuit built-in the cells.

You won't find anything about fires with this system
hall woo is offline Find More Posts by hall woo
Reply With Quote
Old Aug 10, 2004, 07:14 PM
Registered User
Illinois
Joined Mar 2004
372 Posts
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.

Usually there is a condition caused by the user that sets off the chain reaction of events leading up to an accident. Crash and dent or puncture....(I crashed my Tiger Moth 400 with a homemade cell from Chopped-D here on the forum , crunched the 3 cell pack like an accordian and it is OK) , Overcharge or discharge. Abuse.

But anything can happen, like the girl and her cell phone..

LiPo's are great power sources for our hobby and have contributed greatly to the boom our hobby is seeing. I won't give them up, I will be a little more dilligent.

I was told by a sponsored seller here that LiPo's were being deliberatly not marketed to the R/C car market for safety reasons, it seems there was concern that the abuse that the E-car racers have a history of abusing their batteries, and the manu's wanted to steer clear of them. Go figure. I found out about them while building a Brushless RC Car and stumbled across their use in aircraft. Now I am hooked. The sponsored seller was concerned that I was a "Car Guy" and wanted to be sure I understood them before he sold them to me. I appreciate his concern now. He told me horror stories of Kids at a local car track that got them, got hurt, and the track wa almost shut down, and LiPo's were banned.

Just be careful and treat them right. And just go fly.
VBSuperMaxx is offline Find More Posts by VBSuperMaxx
Reply With Quote
Old Aug 10, 2004, 07:28 PM
Permanently Banned
Joined Apr 2003
3,171 Posts
Russell,

We are in the same boat.

Many times, I tried to jump the bandwagon, means
getting the Lipos. Then I read these kinds of thread
and changed my mind, went back to Nimh. Hey,
the new generation of nimh provides excellent
performance, of course for a short time.
I ask myself what do I want and I
self-answer "I want to have fun, not fear."
So, there goes the lipo. I guess, I will never
get into Lipo unless the Lipo plague reduced
greatly. Folks, good luck with your Lipo investment.
rcguy01 is offline Find More Posts by rcguy01
Reply With Quote
Old Aug 10, 2004, 07:42 PM
Registered User
Walled Lake, MI, USA
Joined Feb 2000
11,182 Posts
Kit, I've yet to meet anyone who doesn't make mistakes -- even experts. However, it is possible to arrive at reasonably accurate conclusions by doing a lot of research and homework. I'm far from an expert, but I have probably done more reading on the subject than most in this forum. The only reference I've found to lithium metal existing in Li-poly or Li-ion cells is the possibility of a slight plating out of lithium metal due to overcharging a cell. This would normally be less than a gram, which could provide an ignition source, but in itself would not cause a large conflagration.

If you have better information, please feel free to share it.
Dave Hederich is offline Find More Posts by Dave Hederich
Reply With Quote
Old Aug 10, 2004, 08:31 PM
Striving to Rip the Bring
raptor22's Avatar
San Diego, socal, USA, North America, Earth, Solar System, the Orion arm, Milky way, Universe
Joined Apr 2003
6,320 Posts
My question still exists: it burns white. Elemental Li burns white when ignited. Li compounds tint flames deep crimson red if they burn. Why is the flame not red?

--Alex
raptor22 is offline Find More Posts by raptor22
Reply With Quote
Old Aug 10, 2004, 08:56 PM
Aerobatic Extremist
SharksTooth's Avatar
United States of America For Which We Stand!
Joined Jan 2004
1,346 Posts
Quote:
Originally Posted by VBSuperMaxx
I should clarify , my friend whose house was damaged , and had 2 years experience with Lipos....got complacent. He never had any problems, not one. Except the big one.

He got complacent, lazy, careless. period. He admits it.

I've asked him over and over "didn't you see the start screen? Was it normal? " He just said it all looked fine...unitl 45 minutes later.

Fortunatly this is a rare occurence. I for one, learned from it, and will continue to use Lipo's , albeit with quite a bit more respect.

Thankyou for letting us know about that VB. It takes a real man to admit that he was wrong. It also helps others to not the same mistakes. If it wasn't for the quality of people in this hobby, it would not be what it is today. People are honest, and they are giving and helpful so that all can learn. Even when we tend to stray off and get aggravated sometimes, I think it's really because people mean well and want to help. This is a definite lesson for those that may be thinking of dropping their guard. You cannot make mistakes with these. You have to be very methodical, and check and recheck everything...every time. You cannot ever go without checking the charger when charging one of these. They MUST be supervised...especially during the critical 'ramp up' phase, and the 'charge termination' phase. At NO point during the charge cycle can these batteries be left unattended. Your freind could have very easily died for making such a grave mistake.

Folks, for those of you who read this and are new...

WE ARE NOT KIDDING when we preach this stuff. These things are not a game. They are serious batteries for serious power and they demand respect at all times! Treat them with respect and you will get 'respect' back from them. Get complacent and they'll burn you and your wallet. These people have had the ourage to report these things so that others will understand that directions and warnings MUST be followed to the letter. In fact, you *should* have them memorized. If you do not have them memorized, do not use them until you do. The reason all of us are so serious about this is because we do not want any more incidents. These things are for fun, and they make electric flying even more fun, but like anything else, there are risks, and it's our responsibility to make sure we manage that risk so that we do not get hurt or endanger anyone else.

I love my Li-Po's and wouldn't run anything else on my electrics, and I understand what they are capable of should I not follow directions. I have those warnings and directions memorized...and I follow them. That is why I will never have to witness one of these horror stories first hand. I can say without a doubt that you won't see my name ever being associated with one of these incidents. It's my goal to make sure of that every single time i mess with them. When I am not using them, they stay in the ammo can where they belong. If you are new and wondering "Do I really have to do that?" the answer is yes, or don't even purchase them.
SharksTooth is offline Find More Posts by SharksTooth
Reply With Quote
Old Aug 10, 2004, 08:57 PM
Space Coast USA
hoppy's Avatar
Space Coast
Joined Oct 2000
20,837 Posts
Raptor
Here is the typical composition of a LiPo cell - Since you seem to know chemistry, how about calculating the total amount of Li in a battery that weighs 100g.
Approximate percent of total weight
Lithium Cobalt Oxide 25 35%
Carbon, various forms 10-30%
Polymer 0.1 1 %
Copper 0.1-1%
Aluminum 0.1-1%
Biphenyl 0.1 0.3
Organic Carbonates 5-20%
Lithium Salts 1- 6%
Steel, nickel and inert components - balance
hoppy is offline Find More Posts by hoppy
Reply With Quote
Old Aug 10, 2004, 09:20 PM
...still seeking PyrE
Long Island's North Shore
Joined Aug 2003
176 Posts
To answer some questions:
That - severely past tense - pack, as well as the 3-others purchased at the same time were never in a crash, and were always brought down before LVC - set at 8.3v; no visible damage was noticed. The charger had been checked 5-minutes before and the charge rate was still at 1.0A - always charge at less than 1C, the voltage was about 12.4, but fluctuating as it always does, and the pack was ever so slightly above ambient temp. but the significance of that did not register at the time; in retrospect, not good!
The water depth was about 10-inches, and I'm fairly sure the pack went to the bottom, but the cloudiness of the salt made it impossible to be completely sure.
Wish I could say that those items were at hand, but were gathered at light speed while the pack sat in the Pyrex tray - about 3-minutes, on the workbench - hardened Masonite top, and away from combustible material.

I surely would like to understand the precise reason why this pack puffed, but charging other packs tonight does not show any problem with the '109. The charging now is being done on the cement driveway however, and I suppose will stay that way for now.
Again, some hard lessons learned and others reiterated, but not considering going back.
Stew
FreeFlier is offline Find More Posts by FreeFlier
Reply With Quote
Old Aug 10, 2004, 09:42 PM
Aerobatic Extremist
SharksTooth's Avatar
United States of America For Which We Stand!
Joined Jan 2004
1,346 Posts
Quote:
Originally Posted by rcguy01
Russell,

We are in the same boat.

Many times, I tried to jump the bandwagon, means
getting the Lipos. Then I read these kinds of thread
and changed my mind, went back to Nimh. Hey,
the new generation of nimh provides excellent
performance, of course for a short time.
I ask myself what do I want and I
self-answer "I want to have fun, not fear."
So, there goes the lipo. I guess, I will never
get into Lipo unless the Lipo plague reduced
greatly. Folks, good luck with your Lipo investment.
Sorry, but there is no "plague", only user error. It's not the batteries fault that a user does not follow directions. If there was a case where a battery "self-destructed" I can assure you that we would have heard about it. It simply doesn't happen. There is not one single incident documented that was not result of user error or negligence. They are just like guns. A gun doesn't just decide it's going to go off all by itself, it takes somebody pulling the trigger to make that happen. Li-Po's are exactly the same in that respect...they are as safe as anything until a negligent user goes and causes them to go off. The only reason to fear Li-po's would be if you were planning on not following directions, or just plain paranoia. In either of those two cases, it's better to stick with obsolete technology.
SharksTooth is offline Find More Posts by SharksTooth
Reply With Quote
Reply


Thread Tools

Similar Threads
Category Thread Thread Starter Forum Replies Last Post
Discussion Lipo loss caused by spark 2lakea Batteries and Chargers 8 Apr 29, 2006 05:16 PM