iPhone WiFi data usage / battery drain

i leave iphone overnight maybe 10 hours, when in morning usage time goes 5 hours! resulting in 25% battery drain.

drain / usage seems happen when i'm @ home within range of wifi network. @ work loose 5% battery, , minutes of usage.

no apps running (i have done re-boot sure)
have icloud, yahoo , gmail accounts , not have push email enabled , fetch manual.
location services system items turned off.
have no data in calendar, cannot generating reminders.
wifi sync not used, , imac turned off @ night.
siri off, bluetooth off, photostream off, personal hotspot off.

when check using data usage app, wifi data counter has gone several mb.

can causing this?

 

my icloud backup happens every night shortly after 10 pm. check see time yours happening.

 

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