Why doesn't the iPhone turn on when you plug it in?

slapple

macrumors 6502
Original poster
Jul 25, 2008
442
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I've noticed that if the iPhone 4S battery is completely empty and the phone won't turn on, then even if I plug it in to the charger, it still won't turn on for a few minutes. Shouldn't it be able to turn on immediately once I plug it in?
 

Mac'nCheese

Suspended
Feb 9, 2010
3,753
5,097
I've noticed that if the iPhone 4S battery is completely empty and the phone won't turn on, then even if I plug it in to the charger, it still won't turn on for a few minutes. Shouldn't it be able to turn on immediately once I plug it in?
Nope. Not enough power to even run the os. It takes a few minutes to get enough charge to barely work...
 

chambone

macrumors 6502a
Dec 24, 2011
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Netherlands
I've noticed that if the iPhone 4S battery is completely empty and the phone won't turn on, then even if I plug it in to the charger, it still won't turn on for a few minutes. Shouldn't it be able to turn on immediately once I plug it in?
It should. But for some reason it doesn't. I don't buy the not enough power argument. Even half an amp from a regular usb port should be enough to run the phone, and charge the battery. Let alone the wall charger.
 

Small White Car

macrumors G4
Aug 29, 2006
10,901
1,163
Washington DC
Because if the power just shuts off during boot up it could really bork up your phone.

Of the millions of iPhones out there certainly some people will be dumb enough to just unplug the phone the instant they see the boot-up logo. Since that phone (in that universe) was running off the wall, it just instantly dies again during the boot up process. This is bad.

So Apple decided to not let the phone boot up until the battery has enough charge to do the entire boot up from battery power and, if it needs to, a proper shut down by battery as well.

So, basically, you have to wait for the battery to charge about 4 or 5% before the phone will turn on. It's just safer that way.
 
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slapple

macrumors 6502
Original poster
Jul 25, 2008
442
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It should. But for some reason it doesn't. I don't buy the not enough power argument. Even half an amp from a regular usb port should be enough to run the phone, and charge the battery. Let alone the wall charger.
I agree. Let's say you plugged an iMac into the wall. You wouldn't need to wait a few minutes before you can turn it on, right?
 

JediMeister

macrumors 68040
Oct 9, 2008
3,263
3
I agree. Let's say you plugged an iMac into the wall. You wouldn't need to wait a few minutes before you can turn it on, right?
That's not quite a valid comparison because the iMac doesn't have a battery it runs off of.
 

slapple

macrumors 6502
Original poster
Jul 25, 2008
442
13
That's not quite a valid comparison because the iMac doesn't have a battery it runs off of.
Yeah and I don't think it'd be a disaster if the iMac were to lose power in the middle of the OS booting up.

But what about an MBP with an empty battery? Does it need to wait a few minutes after being plugged in before you can turn it on?
 

Small White Car

macrumors G4
Aug 29, 2006
10,901
1,163
Washington DC
Yeah and I don't think it'd be a disaster if the iMac were to lose power in the middle of the OS booting up.

But what about an MBP with an empty battery? Does it need to wait a few minutes after being plugged in before you can turn it on?
Well, the alternative here is to just have the iPhone die and shut off earlier. (I think that's the Macbook's solution.)

Is that what you'd prefer? To have the phone just die sooner? I wouldn't care for that solution. When I'm away from a plug I'm more concerned with how much time I can get out of my phone than I am with how fast it will turn on once I get home.
 

slapple

macrumors 6502
Original poster
Jul 25, 2008
442
13
Well, the alternative here is to just have the iPhone die and shut off earlier. (I think that's the Macbook's solution.)

Is that what you'd prefer? To have the phone just die sooner? I wouldn't care for that solution. When I'm away from a plug I'm more concerned with how much time I can get out of my phone than I am with how fast it will turn on once I get home.
I think we can have the iPhone use as much battery as possible before it dies, but then it can start up immediately when someone plugs it in. You seem to be concerned about someone plugging in their dead iPhone and then immediately unplugging it once it turns on. Not sure why anyone would do that - if they are dumb enough to do that, let them live with the consequences (which I don't think would be that bad anyway).
 

Small White Car

macrumors G4
Aug 29, 2006
10,901
1,163
Washington DC
if they are dumb enough to do that, let them live with the consequences (which I don't think would be that bad anyway).
You and I are not designing the iPhone. We're not here talking about how to build this thing. It's already been done. No, we are trying to guess what reason Apple has for doing things the way they did.

I like my hypothesis. If you disagree with it you need to come up with another guess. For what reason do YOU think Apple has made the phone work this way?

If you have a better guess I'll consider it. But right now you're disliking my reason and in its place the only thing you have is "I don't know."

Until you have a better guess I'm gonna stick with mine.
 

slapple

macrumors 6502
Original poster
Jul 25, 2008
442
13
I'm not saying your explanation is wrong, it is probably right. I'm just saying I don't know why Apple would design it that way. If OS corruption due to a loss of power is the reason, then I don't think it's a big deal if the power were to get cut off during bootup. It could happen to an iMac, but I don't think an iMac would become a doorstop if it were to happen. Apple could improve the design for the iPhone 5. :)
 

SurferMan

macrumors 65816
May 14, 2010
1,267
51
South FL
I don't think any phone will just turn on after plugging in right after being empty. My GSII doesn't either, it goes right to the battery charging screen if empty.
 

tekno

macrumors 6502a
Oct 15, 2011
842
4
I've noticed that if the iPhone 4S battery is completely empty and the phone won't turn on, then even if I plug it in to the charger, it still won't turn on for a few minutes. Shouldn't it be able to turn on immediately once I plug it in?
This was one of the reasons I switched away from the iPhone. I would regularly need to use my phone but would have to wait 10mins for it to decide it was ready to be switched on.

----------

I don't think any phone will just turn on after plugging in right after being empty. My GSII doesn't either, it goes right to the battery charging screen if empty.
Mine does.
 

chambone

macrumors 6502a
Dec 24, 2011
969
25
Netherlands
If you have a better guess I'll consider it. But right now you're disliking my reason and in its place the only thing you have is "I don't know."
Well, firstly let me admit that I don't have more than an 'I don't know' either, but frankly, your explanation doesn't seem all that plausible to me. After all, is booting up anything more than loading stuff into memory? It's not like data on the SSD gets corrupted or changed if that process were to be interrupted.
 
Last edited:

Netherscourge

macrumors 6502
Oct 11, 2011
329
0
The phone runs DIRECTLY off the battery at all times.

There is no pass-through with a direct wired power connection.

Therefore, the iPhone won't power up until the battery itself has enough charge in it to start up the phone - even if it's plugged into the wall or a USB wire.
 

AlphaVictor87

macrumors 6502a
Sep 7, 2011
797
27
Saint Louis, MO
The phone runs DIRECTLY off the battery at all times.

There is no pass-through with a direct wired power connection.

Therefore, the iPhone won't power up until the battery itself has enough charge in it to start up the phone - even if it's plugged into the wall or a USB wire.
i thought that once it hits 100% it runs directly off the connection so it doesn't harm the battery?
 

isoft7

macrumors 6502a
Oct 3, 2011
757
15
It has anything to do with fear of people unplugging and dying during boot, the phone would not be permanently harmed in that any ways.

Instead it's all about power available... the usb connection, even from AC adapter is not capable of providing the hardware with enough energy to run at full speed, which is what is taking place during the boot process.

Because of this, and because the phone is incapable of bypassing the battery to pull directly from the adapter, it has to wait for enough charge to build up for this process to complete with depleting the battery completely.
 

mrochester

macrumors 68000
Feb 8, 2009
1,965
399
The phone runs DIRECTLY off the battery at all times.

There is no pass-through with a direct wired power connection.

Therefore, the iPhone won't power up until the battery itself has enough charge in it to start up the phone - even if it's plugged into the wall or a USB wire.
This sounds like the most plausable explanation. There's no point in designing and implementing a pass through power system on a device that's primarily going to be used on batter power. It would probably take up space needlessly.
 

Kyotoma

macrumors 68000
Nov 11, 2010
1,996
46
Carnegie and Ontario
i thought that once it hits 100% it runs directly off the connection so it doesn't harm the battery?
No. It stops charging the battery altogether and lets it run down a bit before topping the charge off again. This is why sometimes you'll see that your percentage drops a little quicker than normal when you unplug your iPhone.
 

PNutts

macrumors 601
Jul 24, 2008
4,839
347
Pacific Northwest, US
I think we can have the iPhone use as much battery as possible before it dies, but then it can start up immediately when someone plugs it in.
http://www.apple.com/feedback/

This was one of the reasons I switched away from the iPhone. I would regularly need to use my phone but would have to wait 10mins for it to decide it was ready to be switched on.
If running the phone to empty and the couple of minutes after plugging in are a burden then you were correct to change phones. But it is a choice to let it run down that far and there are battery extenders.
 
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