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Bernie-Mac

macrumors 65816
Original poster
Jul 30, 2007
1,035
1
Sin City, NV
Hey, I heard that if you keep a cell phone on the charger all night that it messes up the battery and although i have been doing that for my all my phones since i got my first one, a $600 iPhone isnt like any other phone ive had and i was wondering, say i put my iphone on the charger at like 10 pm but its fully charged by like 2 am, will it hurt the battery or anything if its just sitting on the charger fully charged for the rest of the night until i wake up in the morning?
 

Joshua8o8

macrumors 6502
Jul 2, 2007
372
0
Honolulu, Hawai'i
Whats up again Bernie-Mac. Haha.

No i dont think leaving the iphone plugged in over night will hurt the battery. I think from like 3/4 way it starts to trickle charge just for that reason. I also think this is why people dont always get a full charge and theres that little space at the end of the big battery icon and the lightning bolt s still on the screen. It only takes about four hours at the most to charge your battery, and when it is plugged in for longer then that it stops accepting charge and starts to run on its battery again. I used to plug it in over night and wake up to it not fully charged. Now i charge it during the day and check it once in a while and i always get full charges, and i have had great battery life. Well thats my theory...
 

unity

macrumors 6502a
Sep 30, 2005
926
0
Green Bay, WI
Its no big deal, the charger electronics know when to quit and cut power to the battery. Now if it was lead acid or something of the sort - bad, but with these modern batteries and chargers its not going to harm it.
 

vrillusions

macrumors regular
Jul 8, 2007
227
2
Cleveland, Ohio, US
iPhones, as well as every other Apple product that uses a battery has smart circuitry built into them. The way a battery is considered full depends on the chemical.

For example when charging a NiMH battery when it gets full there's a drop in the amount of voltage it uses. That's how battery chargers know when to stop charging them. Now if you take that battery out and then immediately put it back in, you could risk that voltage spike never showing since it's already fully charged, and you could then overcharge the battery.

LIon batteries that all the i* products use aren't as smart as that, which is actually good. I honestly don't remember how you tell when one is fully charged. iPods and now iPhones are known for their battery circuitry being too smart for it's own good. That's why you'll see the battery at 50%, plug it in and it immediately jumps to 75%, unplug it and it's at 60%, etc. It's trying to guess how much power you have left. Although you don't have to "re-cycle" a LIon battery for charging, you do have to go through a full discharge/recharge cycle in order for the charging circuitry to learn how the battery charges and to get an accurate guess at how much power is left.

I appeared to have horrible battery life until I tought the iphone. Basically I used it until it was at least 50% or so, then I would charge it over night. In the morning I leave it plugged into the power, turn it off and back on, and let it stay plugged in until it said it was fully charged again. Did this a few times and now the battery meter seems to be pretty accurate and doesn't jump around as much.

...yeah, getting back to the original question. Nope, you shouldn't have to worry about overcharging it. But I wouldn't keep it "topped off" all the time. It's good for the battery if you actually use it. My typical daily routine is leave it plugged in at work. I then don't bother charging it overnight and then plug it in at work the next day. Basically, only charge it once in a 24 hour period. Don't charge it at work, then plug into charger in car, then plug into charger at home all evening.
 
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