I'm actually seeing a TV commercial that claims faulty smoke alarms are a cause of many fires. I'm shocked! I never knew that smoke alarms caused fires. They are there to alert you to a fire. Anyone want to explain to me how they cause fires?
You're probably seeing an ambulance chaser ad. Not something based on reality.
I can't find any record of fires caused by Smoke Detectors when I search Google.
If they did? It would be due to really poor installation. (Bad wiring). Which is more of a house issue - not a smoke detector issue.
A nine volt battery is not enough to start a fire. The old type that runs off one source were known to not activate when their wires burned from the fire. Today's smoke alarms are not going to do that.