I've built a home-brew lighting system for my bike based around a pair of cheap lights (the ones that run on two dry-cell batteries) and a 7.2volt rechargeable battery for a RC car. The original plan was to fit a water bottle cage to the bike, and store the battery inside a bottle to keep it away from the rain/road water. However, I'm thinking I'll probably need an actual water bottle once I start commuting, so I need alternative ideas.
I'll soon have a luggage rack I could fix the battery to in some sort of container, but ideally it needs to be removeable to recharge. Is there a way to add a second water bottle cage to a frame with only one set of mounts?
Any other ideas appreciated