The rechargeable battery that comes with your SwiftPaws will last for about 10 minutes of motor run-time (or about 5 play sessions). It takes about 3-4 hours to fully charge with the included charger and should not be put on the charger if the battery is too hot or cold.
CAUTION: The battery should always be allowed to come to room-temperature before charging. Charging the battery in extreme heat or cold might delay charging or damage the battery/charger. For best results, try to charge the battery at temperatures between 50º and 80ºF (10º-30ºC).