iPhone 5s works 29 minutes by itself on 1h13 min stand-by???

[Racineur]

Hello, my 5s battery acts strangely. Some times, when full charged (charged at 15% power left), I disconnect the charger and leave the phone on my desk as I did today. One hour later, I need to use it and Battery stats show there has been a 29 minutes usage on a 1 hours 13 minutes stand by time thugh Battery is at 100%. What's the iPhone doing? I'n not using it. My photo stream is turned on, so is Bluetooth, but no background app refresh. So what has been doing the iPhone during those 29 minutes it was supposedly sleeping on its stand? Can somebody give me a hint or a course of action?
Thanks a lot

 

[Mlrollin91]

When the phone is asleep it's not dormant. It's searching for cellular signal, the processor is running in the background and so on. It's no different than a computer. It's just idle but not off.

 

[Racineur]

Hi and thanks for the hint but my 5s keeps surprising me. After another ull recharge battery at 100%, immobile on its stand for evening and the night, next morning at first use, I notice 4 hours 12 seconds of usage with 12 hours 3 minutes of stand by time. I can understand it's not dormant but what the hell can the phone be doing for 4 hours during the night? Add to this that battery was at 80% in the morning. Really 20% drain in 12 hours?

 

[e93to]

Certain apps do drain battery in the background - receiving emails, message notifications, news alerts, etc. However, some apps can have bugs that cause battery drain.

For example, I noticed that YouTube app can drain battery if the phone is locked/shut-off in the middle of video (or if the phone's display is locked after the video ends). These are bugs, so if you find the apps responsible for battery drain, please report to the developers.

 

[house1999]

Try turning off iCloud Keychain. I had a problem with high usage and battery drain with both an iPhone 6s Plus and iPad Air. After hours or troubleshooting and searching online and using Xcode instruments to confirm, keychain seems to be the culprit.