tenohfive wrote:You don't need to remove the SIM if you don't want to - if you go into settings you can turn off mobile data and even the generic phone signal I think (it's the data that seems to give the biggest hit mind.)
I agree, you do not have to remove the Sim card BUT you have to switch off the generic phone signal as well. Even with data switched off, the phone will try to find a network signal which reduces battery life significantly when there is only poor network strength or no network at all.
So removing the Sim card is the safest option.
A different solution might work as well: Airplane mode!
I just tested this on my Moto G. The phone signal is turned off completely but the GPS still works.