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Old Apr 05, 2005, 11:38 AM
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Experimental Ignition of a Large LiPo Pack in a Vented Ammo Box

A 4S3P 6000 mah LiPo pack was placed in a .50 cal. ammo box vented with a 3” steel flex pipe, and charged @ 15amps, with a 29-volt limit. The pack was triple-wrapped in fibreglass cloth, about 12 layers, altogether.

The purpose was to test whether the apparatus would contain a large LiPo pack ignition and direct the effluent outside through the pipe.

Details of the apparatus (window closure, pipe installation, etc.) are moot. The ignition blew the ammo box lid open and a three-foot diameter fireball erupted.

The “last gasp” of the fireball was captured in the first picture. The remains of the pack can be seen continuing to burn in the second, looking down into the open box.

It was intended that a progression of tests would ensue, working up to a 5S4P 8000 mah pack. Those tests will be abandoned.

I am now personally convinced there is no safe way to “contain” a large LiPo pack ignition with apparatus widely available at a reasonable price. If I were to fly such packs, I would charge them in an open area where they could simply burn without undue risk of collateral damage.

Tj cooper has done considerable LiPo ignition testing and has expressed an interest in testing large packs in a sealed ammo can. I would advise against it, since even a generously vented can will not withstand the initial pressure buildup. In my test, that buildup occurred over a timespan I would estimate at about a half-second. There was no supplementary air introduced into the box during the pressure buildup.

This test was possible due to the generosity of Charlie Wang, who donated the four packs. The remaining three are at his disposal.

- RD
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Old Apr 05, 2005, 11:41 AM
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Arlington,VA USA
Joined Jan 2001
1,862 Posts
As always, nice work!

I would have loved to seen that on video!
Where did you do your tests?
We are going to have to get you setup with a video system the next time I'm up your way! Let me know if your interested and what your budget is and I can start looking if you like.

I'm discoraged by the results.
Look at it this way, at least you got to complete your tests with a bang!

Next project that needs to be done:
side-by-side comparisons of simular brushless motors.
Same amp (or watt) comparisons with different loads (RPMs), charting RPM differences. Is anybody interested?

Pullin'

PS: Final edit....promiss!
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Last edited by pullin-gs; Apr 05, 2005 at 11:55 AM.
Old Apr 05, 2005, 11:47 AM
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Budget for photographing any more burning LiPos: zero.

- RD
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Old Apr 05, 2005, 11:48 AM
Giz
Tony Rogers
Giz's Avatar
Bath, UK
Joined Sep 2003
2,194 Posts
Nice test RD. The result is a real shame though. I have bought a couple of ammo boxes for transporting lipos but now I am wondering if this will make them more rather than less dangerous.
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Old Apr 05, 2005, 11:54 AM
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Giz, I can't speculate on that.

I can say that I think ignition of a large pack in a vehicle would be disastrous, packaged or not.

- RD
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Old Apr 05, 2005, 12:04 PM
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IA-Flyer's Avatar
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Wow,
Do you have any pictures of the latch assembly showing how it was ripped apart in the explosion?
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Old Apr 05, 2005, 12:04 PM
It's been a while.
Daniel G's Avatar
Irvine, CA
Joined Jan 2005
2,690 Posts
Maybe you should try a more realistic test such as charging the packs at 3 volts more than they should be, or charging them at 2c. That way you would get a more realistic failure. Maybe it wouldn't be as violent of an explosion.
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Old Apr 05, 2005, 12:08 PM
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Bellingham WA
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Hello RD,

WOW!!! That is a real eye opener.

Tom
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Old Apr 05, 2005, 12:38 PM
Flying motor mount master
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San Jose, California, United States
Joined Oct 2004
8,745 Posts
Hate to say it but..

I told you guys so...

if you challenge me I'll find the threads!!!

*itchy search finger ready*
fb

p.s. great grenade possibilities though!!!
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Old Apr 05, 2005, 12:43 PM
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1A-F, The latch didn't break. As with the Brinks box, the pressure apparently bulged the sides outwardly and popped the latch open.

D Z, Voltage at the outset is immaterial, since current controls. The voltage has to be allowed to climb high enough for ignition - a little over 5 volts/cell in series. Current was ~ 2.5C, not much above the current you speculate would be "more realistic".

S.F., yes, it was.

- RD
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Old Apr 05, 2005, 12:50 PM
It's been a while.
Daniel G's Avatar
Irvine, CA
Joined Jan 2005
2,690 Posts
Well if that was the case then I better not be buying any of those big packs until I find a sure way not to slip on the amp or volt rating with my triton.
Great test.
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Old Apr 05, 2005, 12:57 PM
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Nice test RD, thanks!
Amazing!
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Old Apr 05, 2005, 01:22 PM
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Hurst, Texas USA
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706 Posts
Thank you for doing this !
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Old Apr 05, 2005, 05:32 PM
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You're welcome, guys. Be safe.

- RD
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Old Apr 05, 2005, 07:22 PM
Build'em and Crash'em
Ken Lapointe's Avatar
Narragansett, RI
Joined Oct 2000
3,209 Posts
RD,

Thanks for doing the testing.

Charlie thanks for provideing the packs for the testing.

Now I have to figure out how to take care of these packs before I go and buy 2 4S2P packs for my new EDF.

Maybe one of those little plastic sheds out in the back yard would be the way to go. Sure beats chargeing in the house or garage.

- Ken
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