A fascinating educational video on LiPo safety was sent in by a website member.
LiPo batteries are in widespread use in consumer devices. In particular, they are used to power laptop computers. With widespread laptop use in commercial airliner flights, the FAA conducted a series of experiments.
The experiments shown in the video explore the causes of LiPo fires and the effectiveness of various methods for extinguishing them. Yes, the “burning fire” border is distracting and does not add anything to the video. Just ignore it. The video is well worth watching.
I am sure all of us have watched LiPo fire videos before. Heck, I have even seen a couple of them in person. This video is a bit different. These are professionals conducting experiments under controlled conditions. Some of the experiments are very interesting, with surprising results.
The first section of the video looks like amateur footage at the Los Angeles International airport. It looks to me like a laptop was being charged up before a flight. You can see white smoke slowly coming out of it. All of a sudden, it explodes. A fire starts, and there is a lot of commotion at the airport. As the different cells in the battery pack ignite, the fire reignites. My understanding is that the thick white smoke from a LiPo fire is very toxic. Stay away from it.
The next part of the video explains that LiPo batteries become dangerous when their internal temperature reaches 350 F (175 C). A key point is made here: a LiPo explosion can be triggered just by external heating. For example, if the wiring connecting the battery pack to the speed control is too thin and overheats, that is enough to start a LiPo fire.
To underscore the point, next a LiPo battery is shown being slowly warmed up over a hot plate. The battery is not connected to anything at the time. The explosion is quite violent.
The emergency response needs to have two goals. First, to extinguish the fire. Second, to cool the remaining cells so they do not reach the thermal runaway point.
The most effective option is plain water. It kills the fire and cools the battery. If plain water is not available, any soda can or juice drink can be substituted. No, do not use alcoholic drinks.
A halon fire extinguisher can be used to kill the fire. But then you have to follow it up with water to cool the battery. A halon fire extinguisher by itself will not prevent additional cells from igniting.
Very interestingly, they strongly recommend against using ice or other smothering substances like sand. They act like an insulator, actually speeding up the thermal runaway of the remaining battery cells.
- Do not try to pick up or move the battery pack. When a cell explodes, it does so without warning. Serious burns and other injuries can result.
- Stay away. The smoke is toxic. Explosions can be very violent.
- If water is available, douse the battery pack to prevent additional cells from exploding.