Many "experts" cite 20 - 30 wh per mile at 20 mph. My 36V, 10 ah (360 wh) conversion has provided about 14 miles @ 20 mph on level ground, no wind, 70F temperature, 215 pounds or so for bike and rider; didn't check to see what may have been left in the battery. Seems as though something is amiss with your system.