Hi my names Darren From Manchester. Im in the process of converting a mountain bike for my partner to commute to work on. Ive bought a 36v 500w Voilamart motor from eblag...i mean ebay. Im lookin to buy a battery for it. Ive found one that is a 36v 15.5ah 561w. Can i confirm that this will be ok for this motor. Her commute is 6 miles on a very very very slight down hill slope and very very very slight uphill back home. The bike is on road tyres with a kevlar belt and higher pressures to help against rolling resistance. Have i got this about right atall??. Thanks in advance for your input