How to disable the Persistent Wi-Fi feature in iOS4

A day after the iOS 4 was released I upgraded my iPhone 3Gs to benefit from all the new features. I was delighted with the new Cellular Data switch – it allowed my iphone to be a real phone and last for days not merely hours, all due to the GPRS/3G not abusing the battery.

Unfortunately one of the “features” in iOS4 turned out to be an even worse battery abuser – the persistent Wi-Fi. While I was at home or in the office – about 20 hours of my average day – the phone was constantly connected to the Wi-Fi and the battery lasted for 15-16 hours tops, with no more than an hour of actual usage!

So far there is no “Persistent Wi-Fi” switch, so I set on finding out what caused this behavior, and here is what you need to do to get it off:

1. Disable notifications (yes, no more knowing when someone wrote on your Faceboko wall or mentioned you on twitter)
2. Disable any Push e-mail, from the list of e-mails (Exchange, GMail, Yahoo, etc.), not just the Push switch in Settings -> Mail -> Fetch New Data!

If you are using Exchange (or Gmail/Google Apps) you’ll also need to disable your calendar and contacts unfortunately. In other words you have to switch to IMAP/POP e-mails.

This feature, unfortunately, makes you chose between having Push e-mail and notifications or manually turning on and off the Wi-Fi every time you need it, just like those nasty Symbian phones, the iPhone claims to be superior to!

UPDATE: after ten days I have to admit – I was wrong. Probably one of those nasty background-running apps was keeping the Wi-Fi connected at all times. Now I close most of my apps after I’m done with them and battery indeed lasts for 2 days and about 3 hours of use! Cheers!