A lot of them will be fine but some of them are cheap knockoffs and they have unsafe wiring. It's not actually the batteries themselves as they'll probably be the same batteries it's the way the batteries are connected up that makes them more likely to explode.
Unless you are Samsung in which case it 100% was the batteries at fault not the wiring.
Lithium batteries have a very high energy density. When that's released all at once with a short circuit or very high current draw resulting in thermal runaway, that's when these fires start. The great news is, they're self fuelling fires too!
But, most reputable manufacturers, create charging/protection circuits that protect the batteries against such situations. Making them far less likely (but still possible) to happen.
The problem you're going to get is when there's disreputable companies, operating in countries with less stringent safety laws that are operating the production, processing and shipping entirely outside of the sight of countries with safety rules. Well, then you get a product with a fake FCC/CE sticker on it, that is very dangerous indeed.
I will not buy electronics from those sites for this very reason. Batteries, chargers and power supplies are usually very shoddy from these companies.
It's not to say don't buy stuff made by country X. Because there's plenty of stuff I have bought made in, these countries but sold by companies that DO make sure there's some testing done, and they're not fake stickering everything. But, we all know the companies I'm talking about I think. Also, ebay (because private sellers buy in bulk from these places and then resell them) is something to be careful of too.
It can also be due to unsafe charging (over-voltage) or unsafe discharging (over-current, generating too much heat). The actual fire doesn’t necessarily happen immediately during charging/discharging.
I keep my scooter at the farthest point from the apartment exit just to be on the safe side. I also haven't heard many bad things about this particular model (Ninebot G30 Max).
Honestly, don't bother with an extinguisher. The best solution is to put it in a bucket of sand on a concrete floor or something. It's probably safer to just let it burn out than to try to fight the fire.
Yes. These are extremely rare. Some models, like iirc a galaxy note and MacBook Pro have been singled out. The surface and airflow also matter. A laptop kept on a desk spends very little time charging at a time and any heat is dissipated efficiently. All devices are designed with the best thermal performance they can have.
There was actually a house fire a while ago not too far from where I live that forensics said was started by a device in a charger at night. For some units and some uses, they still fail.
Anyway. I think the better safe than sorry is warranted.
My favorite thing about my current phone is that I can set an alarm a couple of hours after I should wake, and the phone (trying not to fully charge until the alarm time) never charges overnight above 80% minimizing the chance of a thermal runaway if it happened to be like the note 7, as well as making the battery have a longer life