HalH

My Feedback: (12)

Last night the business establishment ( Mr. NICAD --Batteries America ) was destroyed by fire. Have not heard what the cause might have been.

c/f

My Feedback: (1)

747,

So if short circuit is only way to set off ignition what causes the big instantaneous fireball? heat or atmospheric exposure? Seems quite rapid for heat from short circuit or is it a spark?

I dont know like I said read and hear allot of urban legends with Lipos. I seen a video in which a swelled pack was shot with a BB gun and it went boom.

It does seem strange that the OEM seems to not regard swelled packs as a timebomb as much as I fear them..............Lends more truth to your statements......

Tom Antlfinger

My Feedback: (24)

Marc:

You are absolutely right.........damaging the pack, which is very easy with the shrink wrapped lipos, and charging without a cell balancer I believe are the two culprits behind the fires most of the time, with shorts circuits right there in the mix as well......just tie-wrapping a pack can deform it sufficiently to cause an internal short to show up........lotsa comments appeared on various websites a couple of years ago when several computer and cell phone manufacturers like Compaq and Motorola were faced with big lawsuits when their packs lit off, often inside cars and on airplanes.....most of it was traced to repeated charging without proper cell balancing circuits....they thought just by reducing the max charge to about 90% they would be home free, but that did not solve the imbalance problem....

I don't mind putting a soft pack lipo on a cheapo parkflyer to save every last oz of weight, but in any jet I own currently, and in my 10X tranny, I only use the 18650 hardcans like Duralites.....and then I never charge the Liths in the house or in the car......

I think Duralite is making a definite safety advance by packaging their Silver and Gold LiPo's in 1mm C/F shells and using cell balancers in-line for charging......

Tom

drvcrash

Ive had two differnet TP packs swell due to overdischarge and heat. WE stuck then both with a long metal rod at the field and nothing happened other than the swelling went down and some gas escaping. These were both gen 2 tp packs.

I have a Kokam 2000 pack that got bent into a perfect 90 degree bend during my trex crashing. I bent the pack back and it still works fine.

Now I try to not charge packs in my car. I have laid on on my front Metal bumper before to charge at an away event but thats about it. I 've beaten up some packs pretty good and still havnet had one bust or flameup

Toro1

My Feedback: (2)

Red, once that baby got cookin' it was a mad scramble to move vehicles, ez-ups, and whatever combustibles were near. What you dont see is the fact behind me were 15 vehicles in dis-aray after moving them. This was in a "heli" area of a club that was mildly populated. The lithiums/charge procedure were the cause of this, as I questioned the owner as I rendered medical aid to him. he said he had a Heli charging in the back and thats where the origin was.

EASYTIGER

My Feedback: (119)

He got HURT, too? Man, that IS a bad day!

Did he also get mugged?


Puffed cells from overdischarging, I have not personally seen any hazard from them, I have three sitting on the bench right now, I don't believe they are a time bomb of any sort. But if anybody knows better, chime in.

c/f

My Feedback: (1)

DRV,

Now thats some ballsy moves IMHO, Now I got even more URBAN LEGENDS on LIPO use/care.................

I am most convinced fire/exlposion potential is 99% related to being hooked up to a charger, but there are many legends of how/what when wrong when everything was supposedly right..............

Jason Shulman burnt up a large model and exterior of trailer, and swears everthing was checked double checked other than he did not remove them from the model for charging...............

EASYTIGER

My Feedback: (119)

Therein lies the problem. We don't know all. Maybe he DID have everything plugged in right. Maybe not. Either way, you DO here these stories, real or imagined, about "I was just standin' there and all of the sudden it went POOF!"
Which is why you DO NOT CHARGE IT IN THE AIRPLANE. Especially in an aiplane in a trailer. Or on the front seat of the car.


How many times is this going to happen? How many people are going to burn their cars down? How many houses? How long until somebody gets killed? Nasty way to die, in a fire.

mr_matt

My Feedback: (10)

All of this to save a couple of ounces in a 30 lb jet?

EASYTIGER

My Feedback: (119)

I think this guy who had the fire did not have them in a jet...
I do think there are uses for lipolys in jets...lighter is better...but if you are not willing to go through the proper procedures, namely...taking the battery out of the plane for charging...then you should not go near these things.

DocYates

My Feedback: (102)

Matt,
The biggest advantage I have seen in using them with the jets is the fact that you can get a few more flights in compared to the NiCd or NiMh batteries, and I am no expert on them so others may have a different POV. For instance on my J600R I can get about 6-7 flights on my 4800 Li-ion battery before I really need to think about recharging it. That can mean a whole day of flying. Before my 7.2 volt NiCd pack needed recharging after 2 flights.
I feel pretty comfortable with the Li-ion pack I have but it gets a lot more respect from me than the other packs I own, it never gets hot but takes a while to charge. I won't charge it in my plane nor my trailer/vehicle, nor unattended. I am happy with it and it was big decision on my part to buy it considering all the stuff I had read and herad on here about them.
Tommy

Gordon Mc

My Feedback: (11)

...but if you have to take the battery out of the model to recharge it, then you could just as easily take the Nicad battery out and replace it with another, already charged one.

DocYates

My Feedback: (102)

Also true....but if I fly all day with it and do not have to recharge until I get home, I don't have to go thru removing the batteries at the field.

We all know there is more than one way to skin a cat, and we all have different ways of doing things, right or wrong, that work for us. I think most everyone knows how dangerous these batteries are and treat them with respect. Just seeing this thread has made me think twice and even has made me regret that I bought them, but now that I have them I am going to use them, with even more caution than before.
Tommy

EASYTIGER

My Feedback: (119)

Yes you can.
But the lipoly will be lighter.
Does it matter on YOUR particular model?
Maybe, maybe not. Saving six ounces...or three pounds?
Your pays your money and you takes your chances, as my old buddy Popeye used to say.
For most turbine or ICDF situations, I doubt if the savings are worth it. For EDF or electric prop models, the difference between nicads and lipolys is...in a word...staggering. It changes EVERYTHING. I am an absolute convert to lipoly, I'm not giving them up. But they are not needed for all applications.
Something like a FC Mig 29, go weigh all the batteries in that plane, you could probably save four pounds or more going lipoly. But then you will have to remove and charge(at c/10) five different packs or something like that.

lov2flyrc

My Feedback: (24)

No denying the added stability factor of the LiIon over the LiPo technology. I have been using the Duralite LiIon packs for well over 2 years now, always charged in my planes, using both the Duralite charger and a Chameleon. No problems ever experienced with them. I do not recall one report of a Duralite LiIon pack lighting off during charge or after a crash. This technology is perfectly safe for our usage with all the benifits Li provide. LiPo on the other hand are volatile, fickle batteries that have their place in the hobby industry but must be used with great caution and guarded during the charge process. Having nearly burned down my house and watched another pack swell during an accurately set charge, I have learned to have great respect for the dangers inherent with this battery technology. For our usage, in turbine aircraft, there is just no need to run LiPo when LiIon provides the same benifits (light weight, high capacity) without the danger factor.
Todd

Tom Antlfinger

My Feedback: (24)

Matt:

It's not just weight, but pack volume as well......My new KC has one of Bennie's new Pegasus HPAS's on it....it ships with a 10 cell, 600maH AA-size Nicad Pack which fits perfectly under the radio board secured to the aft bulkhead....only problem it is only good for 1 flight......I would like to have a 2000-2400maH ECU pack......but have you seen the size and weight of a 10 cell..2400maH sub-C Nicad pack??.....you can start a small car with it!!......that would require me to totally redesign my install, cramming batteries way in the back where they are totally unreachable for pre-flight inspection.......I would have to disasemble the entire 3-tank assembly just to get a look at it....and add another pound.....I fly off grass.....every pound counts on somewhat bumpy takeoffs at just under 40 lbs wet......you asphalt and desert hardpan guys don't have to contend with flex plate-cracking worm bumps......

So instead, jump to 21st century techno.......a 4S1P-2400maH 18650 Li Ion pack actually is smaller and within an oz or two of the 600- 10 cell Nicad pack and fits perfectly in the original battery location.....

That said, I still use SR 5-cell Nicads without regulators on my RX as weight and volume are not an issue with 1800-2200maH packs....

Tom

e-sailpilot86

I hope these urban legends about lipos go away one of these days... [:@]

Anyway, one other thing I'd like to add. Someone said that elemental lithium will explode when it comes in contact with oxygen... I presume that means normal outside air without a spark... not true. HS chemstry labs have big globs of lithium, sodium, and potassium metal stored in jars with a plastic around the metal. Back in HS my chemistry teacher walked around with it to show how it looks, how easy it was to cut, how it oxidized, etc. It does react with the oxygen, but I have to dispell the exploding part. It just oxidizes, after a fresh cut, it looks shiny like metal should look, then it gradually turns white colored in minutes... Lithium oxide. When you need to be concerned, is when you put a small amount of regular water on pure lithium. Heat is released from the debonding of H20 and bonding of the Lithium oxide (wording not quite right with heat release, but reaction is correct), releasing H2 into the air, and with enough heat, it'll react with the oxygen in the air, making an explosion. Most of the time, the reaction is so miniscule, it'll just bubble. It can possibly start a fire, but I'd be much more concerned about potassium and water... She didn't walk around with that one! This just about elementary lithium, not lithium polymer packs. From what I read the actual chemistry is like lithium cobalt oxide or something like that... So, if anyone comes out with a potassium polymer battery pack, unless you're sure it's got stable chemistry and more than just pure potassium, stay away from it! [X(]

mr_matt

My Feedback: (10)

Whooo....peace brothers!!!! I learned a long time ago to never get in the way of a technological solution looking for a problem!!

There are a hundred things to make sure are right in a turbine model, seems like one of the biggest causes of failures (batteries) can just be taken out of the equation with NiCads.

Funny, imagine if Li Pos or Ions or whatever they are called were out first, and someone developed NiCads later. I can see the ad campaign for the "newfangled" NiCads now.......

"Recharge a dead battery to full charge in 15 minutes...imagine....while you are returning your flag, filling the retract air tank, filling the brake air tank, filling the starting gas tank, filling the kerosenes tanks, and getting your flag back, you battery is charged and you are ready to fly again!"

"No need to remove the batteries from the plane while charging!"

"No need to watch over the batteries in a fireproof crock pot with a fire extinguisher handy while charging...heck you can leave them charging OVERNIGHT in your house, get some sleep, and not worry about burning down the neighborhood in the process!"

Oh well, just leave this Luddite out of it, have fun!

......10 cell ECU pack?????



EDIT: added a heap of obligatory smilies so I do not get flamed

e-sailpilot86

lolollol!!

Gordon Mc

My Feedback: (11)

I was kinda thinking the same thing - I guess that's the 21st century for ya ... (Sorry Tom - just couldn't resist that opening, no matter how hard I tried)

There again, if you can save a little bit of weight on a flammable battery pack, that lets you run the world's heaviest miniature turbine brand (I own an AMT too, before anyone starts getting too upset ... though if it takes 10 cells for electric start I think I'll just keep the scuba tank).

Of course, if you run one of those cool turbines that is designed to permit the optional use of an external battery to supplement the ECU battery, and only uses a 4 or 5 cell pack to boot, then I guess there's not much weight savings to be had with them thar lighter-than-air-coz-they're-filled-with-hydrogen batteries

Gordon

Tom Antlfinger

My Feedback: (24)

Gordon:

Just say "12 volts" rather than 10 cells......somehow sounds smaller that way.....

As far as Scuba vs Autostart, I was skeptical about the new Version II ECU....I was ready to re-program the ECU for air-start if the the autostart did not work well....but now with 6 starts while mounted on my new KC, I have found it to be very well behaved with smooth as silk, cool starts.....Bennie has done his homework on this latest iteration of the Pegasus......

Hope to maiden the new Peggy Cat this weekend.......

Tom

warren52nz

I've always heard to charge at 1C. I charge my 2100 at 2 amps... no problems. Actually that's not quite true.... one guy in our club says he studied Li-Po's as an engineer for awhile and you can charge them at 3C until they're at about 80% then taper off to below 1C for the rest to top it up. Says he's done that for years with no problems.

Considering the expense of these things and my requirements, I'm sticking just below 1C. I've got a spare battery to bridge the gap while I'm waiting.

Something else to know.... cold Li-Po's don't work very well so if you're living in less than, say 10°C, you should warm them up a bit before flying. That's about 50°F for you 20th century types. 8^P

TommyWatson

My Feedback: (1)

How true.

I won't use them on my jet models for Radio or ECU power. Apart from the "Possible" danger of fire, the need to remove them to charge, there is also the fact that they go open cct when faulty. Thats not what I want in my models.
I don't need to save weight that bad.

Nicads usually go short cct, but with a five cell pack you just may have enough power to land the thing.
I have used and will continue to use Lipos in my small electric models and thats all.

Nicads for me!!!.

erbroens

Some graphic examples:

http://video.search.yahoo.com/video/...=9.2MB&dur=107

http://video.search.yahoo.com/video/...e=4.5MB&dur=23

RCWorks

Has the driver of that SUV returned to the flight line?

I know the driver but have not seen him in a while, hope he is still not a guest of the sherrif.