Apple Event: May 7th at 7 am PT
Is it harmful to allow my iPhone to charge overnight while I sleep? Or will that cause longterm battery damage? Or is it okay?
iPhone 4, iOS 4.2, Brand New
If anyone need further detail how to prolong your cellular battery can read this article.
http://batteryuniversity.com/learn/article/how_to_prolong_lithium_based_batterie s
actually what he says is partly true. modern laptops (having better battery circuitry) have something called "battery care" (for example sony vaios). what it does it stop charging your battery at a preset level, much below 100% (say 50% or 75%). This reduces the juice for that single charge, (since its charged less), but increases overall battery life (by about a year or two).
I wish there was a inbuilt mechanism in the iphone to specify a level at which to stop charging. The 100% everyday charging is not the best way. Ideally, Li-ions should always be kept around 40-50%.
Of course, you have no way of knowing what the state of charge on the iPhone battery is when it says "100%". It could easily be 70%. The fact that iPhone batteries rarely fail over the useful life of the phone would tend to suggest that Apple takes very good care of the battery.
I've had 3 iPhones. The first I kept for 3 years, charging it overnight, every night. I then passed it on, and the 2nd owner got another year out of it before passing it along. My 3GS is still going strong after 2 years with the same treatment.
The point is that you don't have to do anything special to take care of the battery.
Some numbers
Charging Lithium Polymer has two phases.
First phase, High current until 0~ 80% of battery capacity.
Second phase, Constant voltage with decreasing current, we call top up, charging from 80% tp 100%. This phase typically takes ~ 1,5 hours to reach 100%. This phase that causes degradation of the battery.
I did a quick measurement with my Ipad2, it took about 1 hours 40 minutes in this second phase.(80% to 100%). You may repeat this with your phones.
It may indicate Apple is targeting maximum use of battery capacity in Ipad2 as from consumer perspective translate in hours of use.
Quick note,
When you plot the chart capacity x time you see the change of slope of the curve when the charging circuit move from first to second phase. So you can see from the lope that the charging algorithm is trying o reach 100% battery capacity in this second phase.
My Ipad2 it stays in this second phase 1h and 40 minutes.
FYI,
Apple declare the standard expected life for IPhone, 400 cycles.
By this information we can not expect any special charging algorithm inside IPhone.
What probably the users are seem is the life spam due partial discharge.
From the article I sent, charging from 50% to 100% the expected life spam is 1200~1500 cycles, about 3,6 years charging everyday.
From 0% to 100% the expected life spam is 400 cycles.
Charge Cycles
A properly maintained iPhone battery is designed to retain up to 80% of its original capacity at 400 full charge and discharge cycles. You may choose to replace your battery when it no longer holds sufficient charge to meet your needs.
I hope you really enjoy obsessing over the the useful life of the iPhone battery. The rest of us will just charge it and enjoy the phone instead. You have have far to much time on your hands wasting it developing a solution that has no problem.
That was the obsession of Steve Jobs, innovation which made available IPhone, IPad, etc to the world.
Yes, Apple can change now that Steve is not within us and think it is waste of time and there is no problem, the history will tell.
YES! I've had my phone since January and I used to charge it overnight, just cause it was handy. Two weeks ago I was charging it and it showed me false battery percentage, like it would have been on the charger for hours and say 13%, and wouldn't change all day. Then it kept dying and restarting, keep in mind nothing else was wrong with it. It then died and would not turn on, or even charge, if I did out it on the charger the apple logo would flash and nothing else would happen. I took it into apple and they said it was due to the over charging had damaged the battery and you should not charge it for more than 2-3 hours, one new iPhone later and everything's fine. Even contact Apple, it does damage it.
I think that's a confused Apple employee. The 3GS that I have charged overnight, every night for 3 years is perfectly happy. As is the 4S that I've charged overnight, every night for 18 months.
NO! That was definitely a confused Apple employee. You can leave your iPhone on charge for as long as you like with no measurable damage. You can and should charge as often and as long as possible... deep discharges are hard on lithium batteries. Normal mobile use will result in the one charge cycle/month that Apple recommends.
Probably there was a defect in charging circuit or freeze in charging algorithm during charge that caused overcharge of the battery.
Most cells charge to 4.20V/cell with a tolerance of +/–50mV/cell. Higher voltages could increase the capacity, but the resulting cell oxidation would reduce service life. More important is the safety concern if charging beyond 4.20V/cell.
Lithium-ion operates safely within the designated operating voltages; however, the battery becomes unstable if inadvertently charged to a higher than specified voltage. Prolonged charging above 4.30V forms plating of metallic lithium on the anode, while the cathode material becomes an oxidizing agent, loses stability and produces carbon dioxide (CO2). The cell pressure rises, and if charging is allowed to continue the current interrupt device (CID) responsible for cell safety disconnects the current.
I think it's more relevant using original Apple charger, if you use non-Apple chargers that you talk about can occur..
Overnight Charging.
