Parastic drain and sleepmode.
 

Guys, my battery is draining within a day and have identied its a result of rear fuses 42, 43, 44 or 45 as if they are unplugged, the battery doesnt drain. I have got myself a multimeter and the next step is to find the offending fuse. Trouble is, how do I get the car into sleep mode? And stay in sleep mode as currently with a the fuses pulled I am still getting .7 draw, so guess the car is still awake.

All advice welcome.

I, too, lost my 1st battery early (though not within a day). I now make it a habit to turn everything off (radio, heater/ac, lights) before turning off the ignition. Now I've only changed the battery at my normal 4-5 yr interval. It does draw a lot of juice as the computer is always on and even the cigarette lighters are with power when the ignition is off (which means you can charge your phone over night or at the movies)

Ok, I have left the car unlocked for a while, but wont the car wake up when I open the boot/disconnect the battery/connect multimeter or does starting the car wake up the car,

Yer read your earlier post, but if thats the case, everytime you create the circuit with the multimeter, you would have to wait another 45mins or so, meaning testing several fuses could be a rather lengthy process.

It may not be necessary to wait for sleep mode. Try measuring the draw with the key off and then removing one fuse at a time to see if amp draw reduces. 42 is vanity mirrors, 43 and 45 are instrument cluster and 44 is airbag control module. If removing a fuse one at a time does not locate the draw it may be that it is not going into sleep mode at all. It should go into sleep mode in about 16 minutes. If it does the amber light for gearshift position will go out. It may also be worthwhile to check for error codes.

What year X5 do you have? Would be best to add year and engine to your signature, almost always needed to help.

Even in early E53 models it goes out. I have read owners of almost all E53 years that say it stays on and others that say it goes off. Since other BMW models of earlier years go off my conclusion is it should go off regardless of the E53 year. If so, it should go out in 16 minutes. It can come back on or never go off if something is wrong.

With the fuses OP mentioned removed it should go into sleep mode unless something else like FSR is bad which is not an uncommon fail that causes battery drain.

We need to know year of OP's X5.

I would check for fault codes ASAP.