Lumia 435 standby battery life - Microsoft Community

i purchased lumia 435 couple months ago , i've never been able more 3 days of standby time vs advertised 21 days, when don't use phone @ all.  about week ago, restored phone factory condition, updated phone 8.1, update 2, followed of suggestions here:

https://support.microsoft.com/en-us/help/11546/windows-phone-battery-making-it-last

i turned off or disallowed apps run in background except phone , text i'm still getting 3 days when don't touch phone.  how increase standby time?  even half of advertised 21 days enough.

answer never battery advertised time ridiculous if getting 3 days on standby it's not best not worst either have resign fact that's

Mobile Devices / Microsoft Lumia and Nokia Lumia / Settings / 400-series