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Can I safely charge my iPhone 4 overnight on a regular basis?

Is leaving the phone on the charger overnight really really bad for your iPhone?


Nah. Electricity is PULLED to devices that use it, not PUSHED from the plug. The phone is smart enough to stop pulling when its battery is full.

EDIT: However, an adapter can provide incorrect voltage for a device. Don't take what I said there and wire your iphone power adapter to a 220 source, for instance. You can OVERDRIVE a device with too many volts, but you can't send it "too much" of the right voltage, because the amperage is a function of the device's draw. I know I just said that assuming that you understand the difference between volts and amps, but there it is; they're different.


No, leaving it charging overnight will not have any adverse effects. All you need to do with the iPhone's lithium battery is be sure to drain it once a month for longevity.

Read Apple's iPhone Battery page.

[Similar answer for Apple's lithium laptop batteries, iPad batteries, etc.]

Also see Apple's Lithium-Ion Batteries page for more info.


The answer is it's just like an laptop: If it's left plugged in all the time, then the battery WILL eventually die. So the answer is yes, it's OK to leave it plugged in, but not all the time.

  • 2
    This is not correct. If you leave a laptop plugged in, it is not continually charging the battery - if it was, it would explode! Once the battery is charged, the charging circuit will cut out (or at least cut to a drastically lower voltage). One of the worst things to do to a lithium battery is to continually discharge/charge it, keeping it topped up at 100% will keep it working longer. (For the longest life, discharge it to about 40%, and store it in a cold place)
    – ZoFreX
    Dec 2 '10 at 16:19
  • Tip 8. But then again, I have been known to misunderstand answers. cl.ly/3Tq4
    – jrg
    Dec 2 '10 at 16:31
  • Tip 8 is correct ("Do not leave a charged battery dormant for long periods of time."). My comment wasn't totally clear: if you are using the battery, then you should be keeping it charged. If you are not using the battery, you should drain it to 40%. You should try to avoid draining it completely as much as possible.
    – ZoFreX
    Dec 3 '10 at 9:29
  • Alright. Sorry about being a stickler about this, but I just want to have clear answers here. :)
    – jrg
    Dec 3 '10 at 11:49

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