I'm not sure if it is a good idea to use this device with your rechargeable batteries...
Jokes aside, while the technology and the "why did nobody think of this before" is certainly impressive, if this gets any market traction it will cause more landfill by hurting rechargeable adoption than it will prevent by slowing the disposable battery replacement cycle.
If the chip is very clever, then it'll detect that it's working on a rechargable (from voltage curves?), and stop discharging after a certain point. But the specifics there depend on the exact chemistry used, so it'd be difficult to get it right.
So actually, it would be better if everybody switched to rechargable batteries?
I probably change the batteries every month or so, which is usually about 40 hours of riding. Probably too often, but whatever. The light cost $15, I think.
(Actually I'm retiring this light today and switching to a dynamo-based lighting system. No more recharging ever. Looking forward to that.)