The arc can happen only if there is large voltage difference between empty battery and donor car battery. (mechanics.stackexchange.com)
Therefore, fast charging is mainly suitable to quickly charge an almost empty battery so you can go some additional hours with power. (makezens.com)
There's even scope for a more powerful 22kW charger to be fitted to the next Formula E safety car - Qualcomm says a 22kW charger could fill an i8's empty battery in as little 15 minutes, and perhaps more impressively, it could even fill the much larger battery of the all - electric i3 in less than an hour. (evo.co.uk)