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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.



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