On 2 August 2018 at 17:39, James Cameron wrote: > http://www.abc.net.au/news/2018-08-02/electric-scooter- > explodes-while-charging-in-china/10066416 > Battery begins to vent. Operator disconnects charger. Venting > increases by orders of magnitude. Operator evacuates. Vented gas > ignites. > I rough count: 3 seconds from dog startle to 1st smoke. another 3 seconds to plug pulled out. Under 10 seconds total to "all go". Very commendable action by the user - although arguably the BEST response would be to evacuate the child and then return to the problem if inclination and escalation allowed. What has interested me is; > > - only ten seconds before "flames", > > Yes. MUCH faster than most of seen (in videos only). Some batteries have developed a hard metallic internal short. In a vehicle like this there is liable to be 0.5 - 2 kWh capacity. Could be more. IF say 10% of this can be liberated in 10 seconds, for 1 kWh that's 1000 Wh x 3600 s/hr x 10% /10 seconds =3D 36 kW for 10 seconds. Even a small fraction of that could cause the results seen. > - did the venting increase because of charger being turned off? > > I'd not expect so. Charging a say 1 kWh battery would use at most a 1 kW charger and I'd expect rates more like 100 - 200 Watt max. Whereas the energy available on a full internal battery short could be (see above) tens of kW. (eg say 36V battery at 1000 A ... ! :-) :-( ) The charger probably helped the battery into a fault condition but, once started, the battery needed no help. Russell. --=20 http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist .