E-bike battery capacity is measured in Watt-Hours or Wh. This is the size of the “fuel tank” on the e-bike. Like a car, some motors guzzle fuel, others sip. To calculate the capacity, multiply the voltage (V) used on the bike by the Ampere-Hour (Ah) rating. The OnTime "Breeze" battery capacity is 624wh. The Ontime "Phantom" battery capacity is 672wh.