I purchased a 700C Mini Motor 200W kit and created the battery myself. The battery consists of two 18.4 volt 5ah lipos wired in series, giving a nominal 36.8 volts, but delivers 42 volts at full charge. I have been involved heavily with lipos for the last 4 years flying model aircraft and have dedicated high current lipo chargers. Soldering these batteries is not for the inexperienced. The batteries are model aircraft type from HobbyKing and cost about $43 each, so it makes for a very cheap 5ah pack. For long rides I can take another 4 spare batteries (two packs) in my bike bag and change them when needed. The 3 packs should give me a great range. On my first test with my first battery pack I got 53K out of it! It was a fairly flat ride but I used the motor on any rise in the road. Today I did another ride of 35K with quite a few hills and used 3,500 mah out of 4,600 and that was carrying the extra weight of two spare battery packs. These batteries are rated at 15C and will take a current of 75 amps continuous, so at the 15 amp current limit of the controller, they are having an easy life. The batteries just fit snugly into the tube, which is 65mm plastic downpipe from Bunnings. The battery tube holder is also made from 65mm downpipe and holds the battery tube very snugly but can be easily removed. The end caps are made from 65mm downpipe fittings. The removable top cap is fitted with a switch and a 25amp fuse. The holder is secured to the bike with four 5mm nutserts. The battery tube is painted white to keep the temperature of the batteries down. I started off with it painted black but in testing I found that in direct late summer sun the tube heated to over 45 deg C instead of 25 deg for the white. Both my wife and I are deeply in love with it!