The rechargeable lithium ion XL-B3 is a replacement battery pack for Sound Devices 7-Series Audio Recorders and PIX Video Recorders. The 7.2 V, 6600 mAh battery pack can be used as the primary source for the recorder or as an onboard backup supply. It is charged by the 7-Series' charging circuitry or the XL-CHARGE battery charger.

You can recharge a lithium ion battery pack whenever it is convenient. Unlike Ni-Cad and NiMh batteries, the XL-B3 does not have to be fully discharged before charging. However, as the battery pack will naturally discharge itself over time, it is best to charge it the same day you plan to use it, or the day before. In addition, there is the possibility of damage to the battery pack and reduced usage time if fully discharged or charged batteries are stored for a period of months. The ideal charge capacity for storing a lithium ion battery is about 40%.