In fact, the package of our headlight and SLA battery pack makes for a really great bike headlight system - plenty of light, excellent durability, very cheap running costs and an up-front price that's well under many premium bike lighting systems.

Or if you wish, you can place the SLA battery in a shoulder or belt pack and use it as a very powerful and light hand-held floodlight.

The design

So what makes this design so effective?

Firstly, the light beam is tightly focused by a convex glass lens. But isn't this expensive?

Well, no - not when you use a magnifying glass! The lens used in our bike headlight is a 70mm diameter magnifying glass. And it is actually glass, rather than being made from plastic. Using such a large lens works very well in focusing the beam which is produced by an incandescent bulb and its dedicated reflector.

Secondly, the design uses a good quality multi-faceted reflector. It's from an Eveready torch - model E250K (and it appears that the Eveready E220, E250 and E251 torches are very similar).

This is a two 'D' cell torch with a reflector that's 45mm in diameter. It costs about four dollars so it's certainly not expensive. We'd expect that any torch with a decent quality reflector would be able to be used in this application.

Finally, the bulb is matched very carefully to the battery so as to give a very good output while having appropriate durability.