The iPhone.org - iPhone 4, iPhone 3Gs smart phone fans page. Descriptions, apps, wallpapers,ringtones.

There were complaints about battery life with iPhone OS 2.1, but many on the various internet channels seemed to think OS 2.2 fixed that up rather nicely. Reports since iPhone OS 2.2.1 have varied more widely. Some seem to think it’s fine while others, keep saying they’re getting worse battery life since the last update.

What’s happening with your iPhone? The same? Better? Worse? Can you make it through a day? And what’s with the up and down between firmware? Is Apple playing some high-stakes balancing game between battery life and signal reception?

This is the most common complaint I've heard from the lucky folks who have the 3G iPhone: with some usage, by the end of the day, their battery is almost dead or dead. And, there's no way to swap the battery with a fresh one to fix this problem.
So what's going on? Why did my previous iPhone get such great battery life and my brand spankin' new iPhone gets lousy battery life? The answer is quite simple, and I might add, it's just as it should be: 3G sucks power.

* 3G is faster but at the price of higher power consumption
* 3G gave about 25% less battery life compared to edge in standard web browsing
* Wifi gave the best battery life compared to 3G and Edge
* Leaving 3G enabled during talk time had the biggest impact: a 52% reduction on battery life

How can I get better life from my iPhone 3G battery?

I'm going to let you in on a secret. Well it's not really a secret. All you need to do is turn off 3G when you're not using it. Simple.

Go to Settings > General > Network > Enable 3G and set this to OFF.

You can also try changing your settings for Fetch New Data and Push as well. I did a few unscientific tests but found this worked best for long life during the day. Previously if I ran the iPhone with 3G on and push mail from my exchange server and fetch set to manual by the end of the work day (5pm) my battery was at 25% with very light usage. If I turned off 3G and only used it when I surfed the net then my battery usage was at 75% by the end of my work day.

Okay I've done this but I still need more power! What can I do?

Well the folks at Apple still haven't made the iPhone's battery replaceable and until they do you are stuck with either carrying around the charger or getting yourself a backup charging source!