Most of the fires caused by e-bike batteries are those inexpensive bikes imported from China, and which are the main workhorse of the food delivery workers in NYC. If you look on YouTube, you’ll see lots of security and elevator cameras catching these bikes spontaneously combusting, sometimes with fatal results. When I walk around NYC, I notice that these delivery bikes are usually locked up outdoors. I wouldn’t keep one indoors. Requiring batteries pass UL standards is an idea, but UL labels and CE labels can be bought in bulk and put on anything.