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| Deliberate Lithium cell overcharging |
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| Rerouter:
also to keep the water flowing well after the main event has settled down (can be low flow rate, water is very efficient at soaking up heat, and if its slow you may be able to see the steam if its about to reflare), when the batteries burst in to flame, generally there internal structure has been damaged enough to short out, so you initially extinguish the light show by cooling it down, but you need to maintain that cooling until every part of the pack is discharged, Once the fire is out, you want to remove it from the vehicle, and Ideally leave it in a puddle of fresh water or similar to make sure its cold, you ideally would also want something like jumper leads with a bulb to discharge the pack reasonably slowly, When the battery is at 0V on all cells, then and only then can you turn your back on it and call it safe. In a pinch Co2 extinguishers can chill packs quite quickly (dropping pressure on a gas causes a sub ambient cooling effect) however this is more for gaining time if your waiting on the water sources to come out. the main thing I would say to avoid at all costs is ABE/ABC style extinguishers, the active components are salts, so if you combine that with a recently hosed down wet pack you end up with pockets of highly corrosive brine which will happily eat through most battery casings over a few weeks / months, possibly causing later issues if not all of the pack was drained. |
| Yansi:
--- Quote from: Rerouter on May 11, 2019, 02:44:26 pm ---In a pinch Co2 extinguishers can chill packs quite quickly (dropping pressure on a gas causes a sub ambient cooling effect) however this is more for gaining time if your waiting on the water sources to come out. --- End quote --- In my personal experience, from an environment where rather large 5+ kWh packs were built, CO2 extinguishers are of not much use. Maybe only for small packs, but their cooling effect is very subtle and short-durating, compared to a full bucket of water. DO NOT rely on CO2 extinguishers when handling large battery assemblies! |
| amyk:
--- Quote from: Siwastaja on May 11, 2019, 02:21:25 pm ---Physical nail penetration might be the best, if it needs to demonstrate a typical cause. --- End quote --- Even then, you might not get a fire. I can't find it now but there's a video on YouTube of someone driving a nail through a fully-charged 18650, and all it did was bubble electrolyte out, melt the wrapper, and then cool down boringly. I guess you need temperatures high enough to ignite the electrolyte in order to get anything more interesting to happen. |
| ogden:
Better train your firefighters properly. Internet search gave many hits regarding EV fire training. Just one: https://www.nfpa.org/Training-and-Events/By-topic/Alternative-Fuel-Vehicle-Safety-Training |
| Marco:
I don't see how reproducing the exact way it catches fire is important for extinguishing it, as long as it only burns on its own accord when you start. Wrap a cell in some magnesium ribbon to kick off the festivities? |
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