iPhone 3G/3GS battery life

An interesting thought came to me the other day which is: how long will the iPhone battery last before it needs to be replaced?

I decided to check the Apple site and whilst it has very good information on how much usage you'll get from a charged iPhone, lots of information on care of the battery, a statement the battery has a limited number of cycles, the glaring omission to me is: how many times the battery can be fully recharged, or cycles as they call it.

How many cycles before the battery needs to be replaced. I would have thought that figure should be clearly stated. Replacing a battery probably represents more than 10% of the cost of a phone, so the battery is a fairly expensive consumable.

The other question I have is: if the number of cycles is limited, then if I use the iPhone direct off the power whilst surfing the web using wireless, will that extend the battery life? The answer I think should be yes, but it would be good to confirm.

I've not yet found information from an authoritative source, but one site did indicate a figure of 400 cycles for the iPhone. That's probably a fair figure because if you are a heavy user of the iPhone, meaning the iPhone has to fully recharged each day, then the battery would need replacing in a little over a year. That would be expected based on the information I've read.

If we use the figure of 400 recharge cycles, and then the amount of usage time when using different features of the iPhone, you can get a good idea of how long a battery should last for you.

The battery usage information for the Apple iPhone 3GS is the following. (Credit for information: Apple web site.)

Talk time:
Up to 5 hours on 3G;
up to 12 hours on 2G

Standby time:
Up to 300 hours

Internet use:
Up to 5 hours on 3G;
up to 9 hours on Wi-Fi

Audio playback:
Up to 30 hours

Video playback:
Up to 10 hours

Whilst I haven't done any timing tests, I do find with my current limited use of the iPhone (it isn't my main phone at the moment), that I have to recharge every couple of days. My main usage is internet usage which could be a 1-2 hours a day spread over the day. Given the battery usage information, and that I do use the iPhone for internet usage, I should probably expect to replace the battery every 1-2 years. Most of my wireless internet usage is around the home, so if having the iPhone running off mains power extends the battery life as I expect it should, then I could probably extend the life of the battery to 2-3 years, which would be pretty good.

Interestingly for those looking at a second-hand iPhone, if it is more than 12 months old, they should probably budget for a replacement battery on top of their purchase cost. Those upgrading to new models and selling off their existing iPhone which isn't very old, might indicate they tend to be a power user.

The 3G battery information indicates shorter usage time by possibly 30%, which would result in a significantly shorter battery life. Out of curiosity I decided to check the recent iTouch models and they provide up to 6 hours of playback, which is shorter again. In my recent article on the iPhone versus the iTouch I gave my reasons for going for the iPhone. The battery life could be added as another reason.

It took a while to gather this information, but now having learnt what I need to know, I'm in a better position to know how I can extend the life of the battery, and possibly even avoid the need to purchase a replacement battery.

- Kelvin Eldridge

Tags: iphone 3g battery life, iphone battery pack, iphone external battery, iphone backup battery, iphone battery extender, change iphone battery