I'm not sure why this is an issue. Any bike light that is rechargeable can be charged while still mounted on the bike but really why does that matter. (?) To me recharging while on the bike is usually more difficult. Of course that all depends on the type of connector being used, the type of charger and the various extensions you might need to get the job done ( on the bike ). If your lamp is "Quick release", it's no big deal to slide the lamp off, walk over to the charger and charge ( assuming a self-contained lamp ) . Now if you have a battery mounted to the bike then the issues changes a bit depending on how you have the battery set-up on the bike. One of my bikes has a battery inside a frame bag. On that bike I use an extension and charge the battery while still in the bag. Otherwise batteries are generally easy as hell to remove if just Velcro'd to the frame.

Anyway, Raveman CR500 is black ( with self-contained battery ) and makes for a decent road lamp ( and yes you can charge it on the bike with a phone charger or slide it off the quick release and walk it over to the charger....whatever makes your day )