Invention of the Day
Battery-driven bicycle lights come in three forms;
1. Cheapo ones with limited light output and therefore with limited safety value. The only pro is that they are not worth stealing.
2. Expensive ones with batteries that are also very bright and are the best with respect to times between having to do something, like change the batteries. Which is an expensive process.
3. Expensive ones with rechargeable batteries that are also very bright but have a shorter period between having to do something such as removing the battery and charging it.
Both categories two and three suffer from the threat of theft, of either the whole light or in the case of category three, also the expensive rechargeable battery.
Some batteries have odd screws to help prevent theft, leaving them vulnerable to never being able to be removed without a hacksaw, if the odd screwdriver is lost.
The solution is sort of obvious. A light with a built in combination lock as part of the fixing mechanism. Screws if required for adjustment of the diameter of the fixing element would hidden when affixed or not useful in helping remove the device.
This way, say a rechargeable light could be easily removed for USB charging but very hard to steal. The battery itself could be permanently sealed in the thing, all iPhone like.
It’s one of my better ideas.
While I’m at it, I’d like to see a low battery LED indicator on the lights to prevent the annoying situation of cycling without lights.

Can you cost effectively integrate a motion scavenging device to recharge the battery ?