Power-up and play your Bose S1 Pro system for up to 6 hours using the add-on rechargeable S1 battery pack. This lithium-ion battery installs easily into the dedicated compartment on your S1 Pro for secure and reliable use. Use the Quick Charge feature to recharge your S1 battery pack in a hurry. Up to 6 hours of charge time when used at high-output levels for performance use you can count on. Lithium-ion battery technology provides high-energy density and full-output use of your S1 Pro system without compromising volume level. Dual charge modes allow the S1 battery pack to be trickle-charged while the S1 Pro system is in use with AC power, or when not being used for play, the switchable Quick Charge mode can be used for rapid charging. Permanently install the battery inside the S1 Pro system for safe and easy charging.