GET BATTERY STATE
Read the device's current battery state.
Free. The device must have a battery (bit 7 in byte 0 of POWER_STATE must be
|Data||Battery state (9 bytes)|
|0||Battery load (in %)|
|1-2||Battery voltage (in 0.01 volts)|
|3-4||Battery temperature (in 0.01 degree)|
|5-6||Battery accumulator (raw value)|
|7-8||Battery current (signed, discharging if negative. Raw value)|
A battery is considered as new if the accumulator value is below 0x8000.