Inaccurate battery indicator on your iPhone 3G?
Have you ever wondered about the accuracy of the battery indicator and the 20% and 10% warnings on your iPhone 3G? After a couple of months or in some cases after an iPhone OS update the battery indicator may need some re-calibration.
Re-calibration of the battery indicator on iPhone 3G
However, if you experience a strange behavior of the battery indicator e.g. 20% and 10% warnings coming very soon but operation sustains for a relatively long time afterwards, then you might consider re-calibrating your iPhone’s battery indicator manually.
This can be done in 3 easy steps. You won’t loose any data and this procedure will not destroy your battery though it will add another cycle to the counter (So does every regular charging cycle).
- Reset your iPhone by holding down the sleep/wake button and the Home button simultaneously until your iPhone resets. Ignore any pop-up messages and keep holding down both buttons until the screen turns black and the Apple logo appears. Now it’s ready to learn new values for the capacity of its battery.
- Discharge your iPhone until it turns off automatically. The battery has reached a minimum level and the iPhone won’t turn on again. It shows you an emtpy battery icon and indicates to recharge. You don’t have to force a full discharge, you can just use it as usual until it turns itself off. To deplete your battery faster turn on 3G, Wi-Fi, Bluetooth, GPS (Location Services) and turn up the brightness to max. Then run a video or just start Skype which is an excellent app to drain your battery quickly even without doing anything.
- Fully charge your iPhone. That’s it, just charge it to the max and your iPhone learned the lowest and highest capacity levels of its battery.
Now the battery indicator should show you an accurate level of its charge and decrease more linear during operation.
Should I be worried or bring my iPhone to service?
There’s nothing to worry about, this is a normal behavior for any device using rechargeable batteries as a power source. Most batteries have a limited life span and will lose some capacity over time. Especially the full capacity of a lithium type battery will decrease over time (after increasing a bit during the first couple of cycles) and should be replaced after 2-3 years. In most cases even older lithium batteries will allow you to operate your device but with a dramatically reduced operating time.
This is neither a new trick nor is it a hack. I found this in the Apple support forums a long time ago and just wanted to post this as a reminder. I just got a new iPhone 3G from Apple after the knob of the ring/silent switch came off from my old one. It was a bit loose and the guy in the Apple Store completely broke it off during inspection. He instantly gave me a new iPhone 3G and deleted all data from my old one. Then I went home, put the new iPhone into the dock and restored it from my last backup that morning. 1h later I had all my data back and all my apps running. I didn’t lose anything, even my call logs and text messages were back.
Operating time on my new iPhone 3G is still a bit weak (1 day with 3G/Wi-Fi/GPS on and moderate usage) but increasing after a few charging cycles. My old iPhone 3G did stand 3 (sometimes 4) days with 3G/Wi-Fi on and Bluetooth/GPS off when used sparsely.
Great service from Apple! Thanks.