Lights

The Exposure spark uses CR123 or RCR123.The former are usually available at petrol stations. You can also buy a set of 4 RCR 123 li ion and a charger for about £20, which you can charge any time you like, so I always have two fully charged batteries in the light and two more stashed as a spare, and I have never needed the spare set even after 3 hour rides.

What sort of battery life have you got out of your spark? I'm using the RCRs in mine but haven't done a ride long enough to burn it out in low power. I'm guessing high power would use the juice up pretty fast.