The 4.5 lbs battery pack life varies greatly depending on conditions and use. Jetson's battery assists you with paddling and prevents drifting in currents from the take off point. The more you paddle, the longer the battery will last. The pack has been designed to cover one good surf session, with a good number of waves. Under normal surfing conditions battery should last approximately 90 minutes in the water. Once depleted, it can be replaced with a charged battery pack. If you are one of those water people who wants to surf another session you can purchase an additional battery pack.