I can tell you that it’s illegal in China to park e-bikes inside anymore after entire buildings went up in flames because everyone piled their e-bikes next to each other and when one caught on fire they all caught on fire.

When you walk into most Chinese apartment buildings, there’s a flyer or placard with a picture of a apartment building on fire and a public notice not to bring your ebike or ebike battery inside under penalty of prosecution.

I would also wager that the lacking BMS has quite a bit to do with it.