Hi
Better to buy Li-Ion/LiFePO4 Prismatic Steel Shell Battery Cells
Check this link
http://www.bmsbattery.com/index.php?cPath=1&osCsid=d7ca4090e2e083d7d5da89e5788b4989
These battery mush better and less cost..
I have BL36 all original gears 36V 12 A/h acid battery on 26" bike
My body weight 250lbs / he he / plus weight of bike.
I try to keep 1 way 10km max and back to home. In any weather conditions I have extra 4-5 km to ride, so total average 24km. I think with lifepo4 12a/h I can have extra...