curr data format:

    YYYYMMDD HHMMSS DATA: LLLLL HHHHH NN LLLLL HHHHH NN LLLLL HHHHH NN LLLLL HHHHH NN
                          |              |              |              |
                          Channel 1       Channel 2       Channel 3       Channel 4

    where YYYYMMDD = Date as year, month, day
          HHMMSS   = Time as hour, minute, second
          "DATA:"  = Data identifier
          LLLLL    = Low  cycle total count, units = 2 usec / NN
          HHHHH    = High cycle total count, units = 2 usec / NN
          NN       = Number of counts in total

    Current calculation:
        Let I = Current in amps
            L = Low cycle total count (LLLLL from above)
            H = High cycle total count (HHHHH from above)

        Then I = 22 x [ H / ( H + L ) - 0.5 ]

    Channel 1 = Solar Panel Current
    Channel 2 = Battery Current, negative = charging battery
    Channel 3 = Buoy Current
    Channel 4 = Underwater Hub Current