I've had a python{2,3} script for, like, years, collecting advanced details using ioreg.

Sample output:

    ~> ~/Workspace/toolbelt/battery 
    Temperature = 2967
    CycleCount = 384
    DesignCapacity = 6600
    MaxCapacity = 6362
    WearRatio = 96%
    CurrentCapacity = 5886
    ChargeRatio = 92%
    Voltage = 12162
    Amperage = -1061
    InstantAmperage = 64286
    InstantTimeToEmpty = 8:34
    TimeRemaining = 5:33
    AvgTimeToEmpty = 5:33
    FullToEmptyTime = 5:59

https://github.com/lloeki/toolbelt/blob/master/battery