I was riding up a hill at the end of a very hilly 23 mile ride with a 500 watt motor with a 10.5 battery. On this last hill the motor quit with one bar of voltage showing. I turned off the motor and kept pedaling up the hill with great difficulty. After a while I tried the motor with level 1 assist and it worked! I got home and charged the battery and the bike worked fine. Was it too hot or too low voltage?