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Battery completely discharged down from 37% to 0% whist switched off and on charge.

deano1972

deano1972

macrumors 6502a
Original poster
So, last night when I went to bed I put my iPhone 12 on charge as usual.

The battery was on 37% when I plugged it into the genuine Apple plug charger. I turned the phone off, went to bed and left it charging.

I got up 8 hours later and the phone was completely dead and wouldn’t switch on. At first I thought it was hardware failure but decided to try plugging it back into the charger and attempt to switch it on again. It then displayed the empty battery display on the screen. After around 10 minutes it switched itself on and showed 2% battery.

I left it switched on charging and it charged up without any problems and the battery has been performing as normal throughout the rest of today.

Any ideas What could have caused the battery to discharge from 37% down to Empty whist switched off and connected to the charger?

The battery is just 6 months old and was replaced at an Apple Store. Battery health/capacity was at 100% until it drained completely whist on charge last night. It’s now showing 99% capacity.

Any advice would be appreciated.

Cheers.
 
First guess is, despite what you thought, either the plug wasn't properly seated or there wasn't any power, and the battery drained. No idea how this could be. Maybe you did something while turning the phone off. No other guesses.

Other thoughts: If the phone wouldn't charge while turned off because of some fault with the phone, then it shouldn't have charged enough to power on when you plugged it back in. That indicates to me that when you plugged it back in you had power (at least then) and you properly seated the connector.

See if the problem repeats.
 
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Thanks for the reply.

Yeah I agree it’s possible the cable wasn’t seated in the bottom of the phone correctly when I went to bed I guess but it doesn’t explain how it drained from 37% to completely flat whist switched off.

Just to add the flat battery symbol didn’t show on the front of the screen until it had been plugged back in a couple of minutes and it took a further 10 minutes roughly until the phone switched on with 2% battery. So I reckon it was completely drained dead flat.

I’m wondering if something was maybe shorting out the contacts in the charging port on the connector causing a bridge between contacts when I plugged it in last night. Could this cause it to drain flat instead of charging?

I’ll give the port a good clean out before plugging it in tonight because I can see some dust built up in there.

Cheers
 
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Good point about it draining that much while turned off. I don't have a guess on that. I doubt there was any kind of short like you are thinking; not saying couldn't be, just doubt it.

Just pay attention for a while so if it happens again you may detect a pattern. Good luck with it.
 
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deano1972 said:
Thanks for the reply.

Yeah I agree it’s possible the cable wasn’t seated in the bottom of the phone correctly when I went to bed I guess but it doesn’t explain how it drained from 37% to completely flat whist switched off.

Just to add the flat battery symbol didn’t show on the front of the screen until it had been plugged back in a couple of minutes and it took a further 10 minutes roughly until the phone switched on with 2% battery. So I reckon it was completely drained dead flat.

I’m wondering if something was maybe shorting out the contacts in the charging port on the connector causing a bridge between contacts when I plugged it in last night. Could this cause it to drain flat instead of charging?

I’ll give the port a good clean out before plugging it in tonight because I can see some dust built up in there.

Cheers
Click to expand...
Has the issue been resolved?

Has your iPhone been exposed to liquid, water, or dust in any way ?

Did you use a MFi-certified Lightning cable or MagSafe charger?

What wattage is your power adapter? My MagSafe dock uses a 30-40 watt adapter.
 
goldmac2006 said:
Has the issue been resolved?

Has your iPhone been exposed to liquid, water, or dust in any way ?

Did you use a MFi-certified Lightning cable or MagSafe charger?

What wattage is your power adapter? My MagSafe dock uses a 30-40 watt adapter.
Click to expand...


The iPhone hadn’t been exposed to any water but there was quite a bit of dust inside the charging port.

It’s a standard Genuine Apple 5w USB charger and cable that used to be supplied with Apple phones about 10 years ago.

I’ve given the port a good clean out since and it’s charged as normal over night every night since it happened on Saturday night.

Strange though how it drained from 37% to completely empty whist switched off and plugged in over night.
 
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deano1972 said:
[. . .]

Strange though how it drained from 37% to completely empty whist switched off and plugged in over night.
Click to expand...
About that. The simplest answer seems to be that the phone wasn't really turned off. I'm not sure of the chain of events, but if it is working fine now, and the battery seems fine, then I can't see how it went dead while turned off. That is, phone not really off, and not really plugged in. How it ended up there I've no idea.

Anyway, I'm pleased to hear it is ok.
 
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deano1972 said:
The iPhone hadn’t been exposed to any water but there was quite a bit of dust inside the charging port.

It’s a standard Genuine Apple 5w USB charger and cable that used to be supplied with Apple phones about 10 years ago.

I’ve given the port a good clean out since and it’s charged as normal over night every night since it happened on Saturday night.

Strange though how it drained from 37% to completely empty whist switched off and plugged in over night.
Click to expand...
It appears that the issue has been resolved after you cleaned the port, right?

This is a common problem for iPhone users because pocket lint can build in the port . I personally encountered a friend who had this issue with his iPhone 17PM, which he had purchased on launch day. He was close to returning it to AT&T, but he couldn’t because it was past the return date. I managed to save him from a trip to the Genius Bar by cleaning the USB-C port with my AirPods port cleaning pen. He was experiencing intermittent charging problems.
 
aihpcfl said:
About that. The simplest answer seems to be that the phone wasn't really turned off. I'm not sure of the chain of events, but if it is working fine now, and the battery seems fine, then I can't see how it went dead while turned off. That is, phone not really off, and not really plugged in. How it ended up there I've no idea.

Anyway, I'm pleased to hear it is ok.
Click to expand...

I connected the charger which was definitely switched on at the wall because it had just charged another phone up before I went to bed.

I switched off the iPhone 12 after connecting the charger. Let’s suppose for a moment that I didn’t plug the connector in fully and that you are correct and it didn’t switch off on this occasion either. Draining 37% over 8 hours whist the screen is off and not being used is not normal behaviour for it.

I’m more inclined to lean towards something shorting out the port somehow and causing it to drain.

Yes luckily it’s been fine all week since. I have given the port a good clean out though and paid extra attention when connecting the charger and switching it off when going to bed at night.
 
Yes… the problem seems to be gone since cleaning the port. I can only assume that the dust somehow shorted out the connection when it was on charge and drained the battery over night instead of charging it.
Click to expand...
Which explains why the lightning cable pins wouldn’t meet ends and charge your iPhone. That causes the intermittent charging behaviour my friend described too.

If you frequently work in dirty environments like machine shops or gardening/landscaping I recommend getting the Pelican cases or Rokform iPhone cases they have plug covers on them. I recommended my friend to do the same with his 17 pro max
 
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Conutz said:
I’d book a service appointment at the Apple Store and get them to test it.
Click to expand...
Correct 👍 only if the issue comes back and it doesn’t improve after the port’s cleaned up. The Genius can try it one more time to clean it, test cables and determine if a lightning port swap is needed
 
I've had the same lint issue on my iPhone 17 pro with USB-C, so apparently it's not just a lightning thing. If it weren't for that EU common charger directive mandating USB-C charging, I'd be advocating for Apple to use a MagSafe 3 port for both charging and data like my MacBook Pro does.
 
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Bichon said:
I've had the same lint issue on my iPhone 17 pro with USB-C, so apparently it's not just a lightning thing. If it weren't for that EU common charger directive mandating USB-C charging, I'd be advocating for Apple to use a MagSafe 3 port for both charging and data like my MacBook Pro does.
Click to expand...
I would agree. However, lightning ports and MagSafe proprietary ports require MFi certification from Apple, which results in higher prices for these cables compared to universal USB-C cables, in my opinion.
 
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