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iPhone battery meter is a liar!

J

jellybean

macrumors regular
Original poster
Jun 27, 2006
223
15
I've never quite understood this and I can't seem to find an exact explanation anywhere. If I charge my iPhone up to 100% and take it off charge shortly after it's reached 100%, the battery will drop much faster than if I were to leave it on charge for a few hours after it's reached 100%.

For example, if my iPhone's been on charge all night, in the morning when I start using it the battery meter will remain at 100% for a couple of hours before dropping to 99%.

But if I charge it during the day and take it off charge shortly after it's at 100%, it'll drop to 99% within ten minutes of use.

So in both instances the battery meter reads 100%, but one will last a heck of a lot longer than the other, even though they both start from 100%. What gives?
 
Have you tried running it down until it powers off and then charging it all the way? It may just need to be calibrated.
 
This may sound obvious, but your battery will deplete more quickly depending on what you're using the iPhone for, and what features are enabled.

Five minutes of playing Angry Birds is not equal to five minutes of checking e-mail. Having your Bluetooth enabled will drain the battery more quickly than having it disabled. Screen brightness is also a factor.
 
Batt Problems

Get batt plus, free app. It will tell you how much time you have left for each type of use. Also you let it go to 20% left before you charge and turn on batt pluss. It will fully charge your phone. Do it once a month. It keeps charging for awhile after it says 100% to get a full charge.
 
You may be possibly running apps in the background during the day, when you charge your iPhone. Ensure that once you have fully charged your phone then double-click the home button and delete all the apps that are in the multi-task bar.

Try this and see if it makes any difference. ;)
 
No way of measuring battery accurately so what you see is not surprising. What matters is they will both drain to 0% with same amount of time
 
Easy solution for you:

Setting, General, Usage ,Battery Percentage set to Off. Problem solved.

There is no battery meter that will have the accuracy that you are demanding, because no battery has that kind of accuracy.

If that is your only problem your phone must be doing just great!! :cool:
 
There is a trickle charge. Getting to 100% means it was a fast charge. You need to give it more time to consider it a full charge. Try not to use the phone when charging. Agree with the earlier poster and turn off the battery %. My phone on occasion can be stuck on a certain % for a longer time and drain faster after that. As long as you are getting close to the same usage. Right now, my usage is lying to me. I check to see 2 hrs and 50 min, put it down for 15 min without using, and then states 3 hrs and 5 min. It creeps up. This is suppose to happen to standby, not usage. Just turn off the %. Measuring things by 1% is not accurate and makes people OCD. And if you had the phone for over a year, batt life on any phone is bound to get worse as time goes by and you keep charging it.
 
Wirelessly posted (Mozilla/5.0 (iPhone; U; CPU iPhone OS 4_3_3 like Mac OS X; en-us) AppleWebKit/533.17.9 (KHTML, like Gecko) Version/5.0.2 Mobile/8J2 Safari/6533.18.5)

I agree with Savor.

Apple used to list Fast Charge and Full Charge under the tech specs, they claimed 2 hrs was a fast charge (80%, though it would register as 100%) and 4 hrs for a Full charge (100%).

I don't see it listed anymore but they still list it under the iPod nano tech specs (1.5 hrs fast charge, 3 hrs full charge)
 
I agree with turning it off. 100% charged is 100% charged no matter how you got there, but that doesn't mean the % shown is correct.

From http://www.apple.com/batteries/:

Standard Charging

Most lithium-ion polymer batteries use a fast charge to charge your device to 80% battery capacity, then switch to trickle charging. That’s about two hours of charge time to power an iPod to 80% capacity, then another two hours to fully charge it, if you are not using the iPod while charging.
 
forcetactic said:
No way of measuring battery accurately so what you see is not surprising. What matters is they will both drain to 0% with same amount of time
Click to expand...

^this
There are simply too many variables effecting battery life and performance to provide the user with more than a rough estimation(+-5% best case). With this in mind I feel that the percentage view of battery life only serves to clutter the status bar. The battery icon serves as a more realistic indication of how much information the OS really has on battery life.
Don't get hung up on the percentage shown. Instead focus on the actual battery life.
 
Last edited:
mikelegacy said:
Your battery is starting to gain a memory. You need to do more full cycle charges. (less than 10% to 100% charge)
Click to expand...

NOT with lithium batteries, only the older ni-cad ones.

http://batteryuniversity.com/learn/article/how_to_prolong_lithium_based_batteries

Similar to a mechanical device that wears out faster with heavy use, so also does the depth of discharge (DoD) determine the cycle count. The smaller the depth of discharge, the longer the battery will last. If at all possible, avoid frequent full discharges and charge more often between uses. If full discharges cannot be avoided, try utilizing a larger battery. Partial discharge on Li-ion is fine; there is no memory and the battery does not need periodic full discharge cycles other than to calibrate the fuel gauge on a smart battery.
Click to expand...
 
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