iPhone 4 Battery

[dmize31287]

My battery hasn't been drained yet, I get down to about 20% then I charge it. Last night I went from 100% to 46% in heavy active use (from 6pm to 1am). But I fell asleep on the phone with my girlfriend last night, and instead of being 100% when I woke up, I was at 92% and it seemed to stop charging there.

Any recommendations? Should I drain the battery?

 

[Abarth1200]

Lithium ion batteries don't suffer like old cell technology, nickel cadmium (NiCd) suffered from memory and they needed to be drained empty to be able to take a full charge. Lithium batteries are best kept topped up and draining them empty too often is actually worse than topping them up at 20%.
As for the situation you have had, you were sleeping you might have hit a few buttons and made a few calls or surfed the web preventing a full charge or it just didn't have enough time to fully charge, mine takes a little longer to get from 95 to 100 than it does to get from 90 to 95%

 

[dmize31287]

So far i've been on the phone for about an hour and half (wifi), and i'm down to 56%. Should I just kill the battery and let it reset?

 

[telarmago]

It's worth a shot. You're not alone in having battery problems - I'm still losing 20% per night in standby with airplane mode, no exchange or email accounts, etc.

 

[insidmal]

lithium ion batteries generally charge in 3 stages.

STAGE 1
The maximum current is applied to charge the battery until the cell voltage limit is reached

STAGE 2
Charge current decreases as full charge is approached

STAGE 3
Topping charge, minimum current is applied until full charge is reached.

So as you see that first 70% usually flies up in the first hour and then after that the charge speed decreases over time to prevent overcharging. Usually the last 3-7% of a battery is not charged or can take twice as long as the first 70%. Overcharging on a lithium ion cell , the lithium becomes unstable and can begin to plate or leak out of the battery, thus the battery and charges are designed to do everything possible to prevent the battery from overcharging. This is why the more full the battery becomes, the slower the remaining percentage will be.

Thankfuly lithium ion batteries do not have a 'memory' or anything like that which previous traditional nickel cadium batteries had so it doesn't matter how full or how empty the cell is when charged, however fully emptying the cell can reset the circuitry that is used to display estimates of battery life. However just how over-charging it is damaging to the unit and unsafe, so is over-draining it and most lithium ion batteries are circuited to cut off power in the last 3-7% of battery life, this why a lot of times when your battery dies you can still turn your device on, all be it briefly.

Charging it in your wall vs usb can tend to be slower, but also safer since it uses a lower voltage to charge the battery and more preventative of over-charging, though the way the battery is designed you shouldn't ever have any issues by charging it usb-only.

Your battery will ALWAYS drain no matter what you are or are not doing, even with the device turned off, again it is a safety feature of the chemicals in the battery, this is actually something that does help keep the battery working longer. If you have not used your device for a long period of time (several days) without powering it on, it is better to let it discharge before you charge the cell as shunts may begin to form inside the cell which can cause extreme heat and instability when charged.

 

[CashDude]

Is it good to always leave my phone plugged in when I'm home?

I have a 6 foot cable in my room, so I just always plug it in.

It is only unplugged when I go to work or to run errands and such.

Is this good, or should I let it run low occasionally? Will plugging it in all the time cause the battery to wear out and drain faster when I unplug it?

Thanks for any insight.

 

[roland.g]

I actually called AppleCare this morning to get a case number. My phone was 100% this morning at 6:30. 4 hours later at 10:30 it was at 88%, down over 10% in 4 hours, on pace for 40 hours of use. Rated at 300 hours standby.

Now I had not made any calls, nor listened to music or anything of that sort. I sent 1 email today. That's somewhat disturbing for standby. My screen was off and I always lock it when done so as to save battery.

Yes my WiFi is on and logged in at work and at home. Yes my 3G is on. Yes my GPS is on. Yes my Notifications are on. And NO my Bluetooth is off. I have Push turned on for my mail. But the most important factor is that this is inferior performance to my 2 year old 3G that I just replaced, which has all the same things turned on/off. So I am comparing apples to apples. 🙂

I am currently running a video test to see how much battery drains in 1 hour of movie watching. Should be approx. 10% if it is rated at 10 hours, but could be slightly higher with my settings taken into consideration. However, if it is much greater, I will be worried.

I would expect that a brand new iPhone 4, even with my settings and light call usage, and light other usage would still go 2 full days on a single charge.

On another note, Abarth1200, I was unaware that it was better to charge from half full and keep topping than to charge from 10 or 20%.

 

[fossil7379]

I've had no issues with my iPhone 4 battery. I left it unplugged at 100% over night to see how it would do and when I woke up it was at 99%. I have 3G, wifi, location, and push on. No bluetooth at all. I normally just loose 1 or 2 percent over sleeping and I use the phone for my alarm clock.

I have noticed that when you open the default mail app that when it updates the mailbox it will keep looking for updates nonstop till you restart the phone. I had this happen on my 3G a few times. It would just hang on updating and thinking if I exit the program it would stop but I would then feel the back of the phone get hot and notice I've lost like 20% of my battery in just half an hour even tho it was locked and on stand by. I'm sure that was the cause because I always lock the phone after I'm done with to save battery life and those few times it did, checking my mail was the last thing I did.

I'm not sure if other progams do the same thing causing your phone to hang but I've only noticed it with the mail app in particular.

 

[roland.g]

I've had no issues with my iPhone 4 battery. I left it unplugged at 100% over night to see how it would do and when I woke up it was at 99%. I have 3G, wifi, location, and push on. No bluetooth at all. I normally just loose 1 or 2 percent over sleeping and I use the phone for my alarm clock.

I have noticed that when you open the default mail app that when it updates the mailbox it will keep looking for updates nonstop till you restart the phone. I had this happen on my 3G a few times. It would just hang on updating and thinking if I exit the program it would stop but I would then feel the back of the phone get hot and notice I've lost like 20% of my battery in just half an hour even tho it was locked and on stand by. I'm sure that was the cause because I always lock the phone after I'm done with to save battery life and those few times it did, checking my mail was the last thing I did.

I'm not sure if other progams do the same thing causing your phone to hang but I've only noticed it with the mail app in particular.

Mail can certainly be the problem. IDK. I do like that with 4.0 you can easily kill apps in multitasking, and maybe the answer will be to turn mail push off. But I'm fairly sure I had better battery performance on my 2 year old 3G last week.

On the video note, 10 hours (600 minutes) of battery life is 60 minutes per 10% or 1% battery life per 6 minutes of video. I played a movie and it stuck to that timeframe. 30 minutes took 5%, 1 hour took 10%.

 

[Abarth1200]

It's probably much and such the same really, no harm either way in general use

 

[insidmal]

Is it good to always leave my phone plugged in when I'm home?

I have a 6 foot cable in my room, so I just always plug it in.

It is only unplugged when I go to work or to run errands and such.

Is this good, or should I let it run low occasionally? Will plugging it in all the time cause the battery to wear out and drain faster when I unplug it?

Thanks for any insight.

if it's the factory cable then that isn't a problem, both the factory cable and your battery are designed to reduce current as the battery fills, in fact most times the battery will never 100% charge because the battery and charger will cut current lower and lower as it gets more and more full that it usually never reaches a cut off point, this is built into the battery so really you should be fine with an aftermarket charger too but I would use the factory one to be double-protected.