If you are looking for a lightweight lights for your bike and would rather not go through huge amounts of batteries riding back and fore to work each day. These tiny Flea 2.0 USB bike lights might well be worth a look.
Designed and created by Blackburn Designs these tiny cycle lights will provide 40 lumens of light from the front set of 4 super-bright white LEDs, that will run for 3 hours on steady or up to 5 hours flashing on a single charge. With the rear red lights will provide 6 hours steady and up to 12 hours flashing on a single charge.
Once flat the lights can simply be plugged into any USB port to fully charge again and comes with a solar charger if required. The Flea 2.0 lights weigh 17 grams and are available to buy for $30 directly from Blackburn Designs.