In 2007, the FAA issued rules about lithium batteries writing, "In general, lithium ion batteries are significantly more susceptible to internal failures that can result in self-sustaining increases in temperature and pressure. ... The metallic lithium can ignite, resulting in a self-sustaining fire or explosion."
Hans Weber said it's possible there was a problem with one of the lithium ion batteries on the Dreamliner in Boston, but he added, "If this was a problem with the lithium ion batteries, that would be a first."
Boeing said it traced the fire to a battery in the planes auxiliary power unit.
But planes are attended unlike bots in houses. Some have Halon fire suppression systems. As long as appliance batteries are from premium brands, computer companies etc., chances are low, but all risks to houses are low. Already we're advised not to use off brand batteries in laptops and phones. There are tornados here every year, but will your house be the single one they take? It's just a special case, houses.
Lets here what Kobold says. Germans also push auto technology with no speed limit autobahns everyone likes -- maybe just their style. Everything has risks of some sort, so could be over blown. There just seem to be perfectly good Nickel batteries for vacuums, so why bother? Or always be at home when using LiOn (or have the staff at home; the buttler can handle it between wine decantings).
Oh, and forgot: no need to pile this on top of poor charger contact melting plastic. There's enough to handle already.