lots of sophisticated English here.
I charge my batteries at my house. has very relable HVC -high voltage cut off.
the thing is what kind of battery do you use on your bike.
Lithium Polymer is famous for fires not just on ebikes also RC hobby.
I would worry more about my car sitting in the garage with even half tank of gasoline which has much more energy than my ebike battery.
As like others wrote above buy from reputable seller brand name ebike 2000 dollars plus and you will be safe.
If you paranoid just charge in the fireplace .