Background apps are they needed

Have an Asus transformer T100taf that is having battery problems. After a full charge and doing a shutdown, the battery is drained overnight. Battery usage info does not show a problem with the biggest user being the screen.(turns off with shutdown) After chasing this problem for several weeks, found a solution. I have turned off all background apps and leave them off. I see no apparent loss of function or performance. I assume they are in the background so as to give a faster start up of a particular app? I "think" that what might be happening is that wifi is still on?? updates are checking/installing, scans etc. I further assumed that when you did a shutdown, it meant just that?? Since I did this ~2 weeks ago, battery might loose 1-2% overnight. What am I missing that MS thinks these apps need to be turned on?

I simply went down the list of Background Apps, around 55 in all, and switched them all Off.
I switched On - Mail, People, Settings, Weather and that's all.
Mail and Weather I have Live Tiles so obviously they need to be On.

It's entirely your choice, what you don't want/use obviously Off.

Being Off won't stop you using any of those Apps, just stops pointless junk running in the background.