Default Drain battery only on 3g

Hi all,

from few days I have this problem: under wifi my M7 (all stock, sense version, no root) consumes 2-3%/hour in standby, but under 3g increases to 12-13% (according to Gsam Battery Monitor Pro)

I really don't understand why: settings of previous battery drain problems (particular apps, mediaserver process, gnow, google location ecc) are ok and, however, why under wifi all is ok?

While I use the phone, usage drops to normal: the problem occurs only in standby, with screen locked.

I will root to analyze deeper wakelocks but is there something that I haven't checked?