The Arduino _board_ is not designed for running of batteries and is inefficient. The AVR _microprocessor_ is very efficient; that article links to http://www.gammon.com.au/forum/?id=11497 which documents a draw of 360uA in sleep mode. Even the 15ma of "fully on" is equivalent to a single LED.
The main power consumer in the GSM case is of course the GSM transmitter, so it's no suprise that he can improve power consumption by turning it off.
Generally on more powerful machines you take for granted the operating system, firmware and their many conveniences, but often there will be bugs or poor design decisions that increase power consumption by quite a lot.
The main power consumer in the GSM case is of course the GSM transmitter, so it's no suprise that he can improve power consumption by turning it off.
Generally on more powerful machines you take for granted the operating system, firmware and their many conveniences, but often there will be bugs or poor design decisions that increase power consumption by quite a lot.