What is Shure's estimate on how many times a SB900 battery pack can be recharged?
An accurate estimate is elusive as it depends upon multiple variables, such as storage temperature, storage capacity, actual usage, etc. Shure estimates that a single SB900 may have a maximum of up to 500 pro-rated cycles.
One full cycle is the complete discharge of the SB900, followed by complete charge to "full." As an example: the SB900 has a "expected battery life cycle" of about 12 hours. If the SB900 is used for 4 hours, then charged charged to "full" after each 4 hour use, it would take 3 usages to equal a 1 full cycle. "4 hours" times "3 uses" = 12.
A Shure customer reports using the SB900 for 170 hours of operation and the battery indicates a health rating of 97%.