General Question

sferik's avatar

When I connect my iPhone to a power source, after the battery has drained, why does it take 10 minutes before booting up?

Asked by sferik (6074 points ) March 14th, 2010

When my iPhone’s battery runs out of juice (yes, I’m aware it’s not actually filled with juice) it powers itself down, as do all my other rechargeable-battery-powered electronics. However, unlike the other devices, when I plug-in the iPhone (even if I do so immediately) it remains unusable for about 10 minutes, displaying this frustrating screen: http://twitpic.com/18orwe.

What about an iPhone is different from, say, a notebook computer, which can start booting up as soon as it’s connected to a power source?

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21 Answers

DeanV's avatar

I’m pretty sure it needs a certain amount of battery to boot (for recovery/memory) issues, and it takes about 10 minutes for that amount to be reached.
My iPod classic does that too.

sferik's avatar

@dverhey right, but what is that not the case for laptops or other electronics? What exactly about the technology causes this difference?

As far as I can tell, they all use the same kind of batteries. Is the difference related to the type of bootable drive (solid-state vs. hard disk)? Do laptops with SSD have the same behavior as iPhones? (I don’t think so.)

TLRobinson's avatar

Can’t offer you an answer; but I will say, mine does that too! Ugh…

DeanV's avatar

@sferik I really have no idea. I would guess it would be because other devices have other forms of recovery plans.

timtrueman's avatar

I can’t find anything to back this up but my understanding is lithium-ion batteries can be permanently damaged if discharged to too low of a voltage (3V if I recall, 4.2V is fully charged). So for the long term safety and life of your battery it lets it get out of the (near) danger zone before you start drawing significant power from it (They kind of have to consider the case where your computer is booting and say the power goes out and you cannot shut the computer off safely in time I would imagine).

ShiningToast's avatar

@sferik Maybe because iPhones use flash memory vs. the physical hard disks of a laptop? That would be my guess.

EDIT: Whoops, just read your other post now. Yeah you and I seem to be thinking the same thing…

timtrueman's avatar

It has nothing to do with drives.

ShiningToast's avatar

@timtrueman What, then? I’m curious too.

timtrueman's avatar

@ShiningToast Read my first answer.

ShiningToast's avatar

@timtrueman I did. Doesn’t explain the immediate availability of a laptop (unless I’m not comprehending this correctly, which is possible).

timtrueman's avatar

Ahh I see the disconnect. I have seen the exact same issue on Apple’s laptops (many times, it was not a fluke—just ask @andrew). There is no difference between iPhones and MacBooks in this behavior. It’s an Apple safety decision I believe. Other manufacturers probably do it as well.

ShiningToast's avatar

@timtrueman Ok makes sense. What I think happens is that Macbooks go into “hibernation” before their batteries are completely drained past that point, so when you plug them back in they snap back because there is some residual power conserved on purpose. iPhones just go dead.

timtrueman's avatar

Yeah hibernation stores the contents of your memory to disk and essentially shuts down entirely which means the battery will maintain its current state. If you put it to sleep at 10% for too long you would see this behavior or if you didn’t have enough free space to save the contents of memory to disk. I’m guessing the main difference is just the software for managing it is different and the iPhone’s storage isn’t fast enough to do hibernation.

Also interesting to know is if you wanted to store a battery that would be unused for a while don’t leave it fully charged. It will lose less of its lifespan if you store it at 60% in the coldest possible place in your home. And definitely make sure it’s disconnected so nothing is drawing even a milliwatt from it.

ShiningToast's avatar

@timtrueman Thanks for clearing this up, you seem like a knowledgeable fellow. :)

timtrueman's avatar

I worked with lithium-polymer batteries (the slightly higher energy-density brother of lithium-ions) in college. We used a high-capacity (greater than five kilowatt-hour), high-voltage (~200 volts if I remember correctly) custom battery pack for our solar car.

JeffVader's avatar

Perhaps it’s trying to teach you a lesson!

breedmitch's avatar

After reading this last night, I let my iPhoine battery die completely. I connected it to a cord, got the same (similar) screen as you, Erik, and waited. In two (exactly two) minutes it vibrated and was ready for use again. Was your wait time of 10 minutes hyperbole or does my phone take less time because it is the newest model? Anybody know?

timtrueman's avatar

@breedmitch My guess would be it totally depends on how low the voltage on your battery was…it probably has a minimum safe threshold that until it hits you cannot start it up. If you had let it die completely then wait an hour or two it would have needed longer I suspect.

breedmitch's avatar

I’ll try that next time.

bob_'s avatar

To give you enough time to think “why didn’t I get a BlackBerry?”

DeanV's avatar

@_bob Because they suck. Didn’t take me ten minutes.

…even though I know you’re joking.

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