iPad iPad Pro 9.7 charging issue

[zhaoxin]

After installing iPadOS 13.3 beta and overnight, I couldn't charging my iPad Pro any more. With Mi 20000 mAh mobile power bank, there was no thunder mark on iPad. The same was with ZMI charger and iMac 5K. The only somewhat working was with the Apple original 12W charger, but there was no thunder mark either, it said "no charge" before the battery icon. However, the percentage did go up, with very slow speed. Actually, it charged from 10% to 43% in around 5 hours.

Since the iPad Pro 9.7 was out of warranty, I had to go to a third party to fix it. With about USD43 I had my iPad Pro replaced the lighting bottom insert. The fixer told me to take my charges and lighting cables when I picked up my iPad so I could test it there. I had three original Apple lighting cables and I took two of them. I had two chargers and took both of them. I didn't take the power bank.

After testing, I surprisingly found that both of my chargers and lighting cables can't charge the fixed iPad. The fixer was surprised too. He said quickly that he did replace the lighting pack insert and the iPad could charge with their charger. He showed it to me and it was true. But I didn't what to believe that both of my charger were broken together as they could charge my iPhone and their iPhone. Finally I had to accept the fact that I have to buy another charger. I did that and I went home.


---------after home-----------

I tested the new charger, it was a Pisen USD5 charger 5V/2A. It could charge my iPad Pro. However, only with one of the three cables I usually used. I didn't know what's wrong with the other two lighting cables as I said they both worked with my iPhone. I ti ed each of them a knot and put both aside.

I looked my accessories up and find two other lighting cables. One was ZMI with the power bank, and the other was original Apple cable which skin was broken so I decided to stop using it years ago. The good surprise was that both of them were working with the new charger.

I restored the iPad Pro with iPadOS 13.2.2. Now it can charge with the Pisen charger and iMac 5K. However, it still doesn't work any more with the power bank.

I bought another two Anker MFI cables and will see the result.

My question is, if a charger and a cable works with iPhone, why is there no response with the iPad Pro 9.7?


---------updated for Anker cables-----------

Now I have got the two Anker MFI certificated cables. Here are the interesting facts.

1. Only one works with the iPad Pro. The other doesn't work with the iPad Pro, but like my other lighting cables, it works with my iPhone.
2. More interestingly, the working cable can works with all my previous chargers and even the MI power bank.

So now I have cables that behave in three ways:

1. All works with iPhone.
2. Some work with the iPad Pro but only through the Pisen charger.
3. One the Anker MFI cable works with all chargers, Pisen, Apple 12W, ZMI 18w, and the MI power bank.

Even though I am a software engineer, I am speechless and doesn't know this is a software issue or a hardware issue.🐒

 

[cynics]

Without testing equipment we are only guessing here. However I have a USB voltage tester that I can demonstrate what is going on. Too long, didn't read is at the bottom....

The iPad especially the iPad Pro 9.7 and newer/larger have higher power requirements for usage and charging than a standard mobile devices. That is why you can charge an iPhone but not an iPad with the same charger and cable.

As you experienced 'not charging' doesn't actually mean its 'not charging', its using all or nearly all the power from the charger for usage. You are at the point the iPad is capable of consuming more energy then the charger is supplying. That is your variable btw. Software is using hardware that is using power and depending on what the iPad is doing (indexing spotlight for example, figuring out faces in photos, etc etc) it could be outside your control. Using extremes for an easy example, in air plane mode with the iPad locked it might actually be charging. However screen full brightness exporting a video it might be consuming more energy then its charging thus using the battery and 'not charging'.

MacBooks are similar in that regard. Under a heavy load you can exceed the power adapters output which will be supplemented by the battery. During this time the it will report to you that the power adapter is plugged in however the battery is not charging.



The battery icon is solid with a lightning bolt quickly indicating both are being used. When you remove the application causing a heavy hardware load the battery icon becomes hollow indicating its not being used and its charging again. Also 'not charging' will be replaced with time remaining.




I don't know where that 'charging/not charging' threshold is with iPadOS or how quickly it updates. But if your power coming in is too low, the load on the device is too high or both then it will not be able to charge. Again those are variables that can quickly change which is why few MacBook users notice this. In theory a heavy load that last long enough can kill the battery even if its plugged in. Although it might start to throttle because the step after that is a system crash due to inadequate power supply.

The reason this is even a thing is because you can use different chargers with USB-C PD (and the iPad).

The main thing with an iPad though is to use high quality charging equipment that exceeds minimum requirements. I would guess you have a bottleneck somewhere and just can't see it. Here is some examples over bottlenecks and charging overhead...

This is my iPad Air 2 plugged into a USB charging station that is capable of 5v/2.4amp output and I'm using a 6" lightning cable. In theory this is capable of (5 volt x 2.4 amp =) 12 watts.



11.391 watt is the actual output from the charging station (4.86volt x 2.344amp = 11.391watt). That is adequate to charge your iPad Pro 9.7.

Charging bricks/stations/etc have limitations with their voltage regulators as well. The more expensive and larger chargers have more capacity, which is why a 5 watt charging brick is smaller than a 12 watt. The more energy they output the harder its working. If you use a USB load testing device you can keep increasing the power consumption until the charge shuts off on over current/short circuit protection.

A charger needs to maintain the 5 volt DC output at its rated amperage. A very high quality charger will just shut off prior the voltage dropping too much. OEM chargers will do this. If voltage starts dropping the current will be reduced. If minimum requirement is 10watt, using a 10 watt charger is not optimal.

If I plug into a generic battery power bank using the same 6" cable that CLAIMS 2amp (5volt x 2amp = 10watt) I get....



4.709 watt (4.89 volt x .963amp = 4.709 watt). That is what will give your iPad Pro a 'not charging' indicator. The above limitation could be due to voltage drop or just a cheap product that is a rip off.

Battery power banks also have even more limitations than wall chargers because the internal battery has output current limitations inherent to the build quality plus it needs to step the voltage up from 3.7 - 4.2 volts to 5 volts out. Like wall chargers exceeding the rated current SHOULD causes a protection circuit to activate and shut off the unit.

This is a power bank rated at 2.4amp but I'm exceeding it with a 2.665amp load, the voltage is dropping severely from the required 5vdc. This is likely the power banks internal battery not being capable of higher amps. If an iOS device was capable of pulling that much current it would step back to 1amp due to the voltage drop.



I mentioned I'm using a 6" cable for the iPad. This is important because the wire that runs between your iPad Pro and the charger has electrical resistance. A short and/or high quality cable will have minimal electrical resistance due to it using high quality copper conductors that are the correct gauge (wire diameter).

This is the same charging station as before except instead of using a 6 inch lightning cable I'm using a 3 foot MFi cable that has been floating around for a while...



9.640 watt, this is a loss of 1.75 watts. This cable is bottlenecking performance but its still charging. Without this USB tester I would be under the impression my 12watt charging station was delivering 12watt not 20% less.

Cables that are breaking near where the cable meets the plug or if the contacts black/brown/green should be discarded asap. A faulty cable can "work" but can cause the device to charge 2-3x slower.

Ironically Apple caught a lot of flak for MFi Lightning cables w/ lock out chips. Yes, money is a big motivator for that decision however just as importantly the cable needs to be tested by Apple and meet their minimum specs because it far exceeded common USB charging capacity specs at the time of launch. This is a NEW USB 2.0 cable that came with a Sony product I bought, pulling lightning cable rated current through it causes the voltage to drop to 4.09 which is well outside the required spec.



While not as big of an issue anymore with USB-C and different types of fast charging standard, Apples motives for a faster charging standard out of a normal USB-A plug were YEARS ahead of the competition. This is why a standard USB port on a PC couldn't charge an iPad 1 and why the first Android tablets used proprietary chargers (barrel plugs) similar to laptops. I had a Motorola Xoom that used a barrel plug, and a Galaxy Nexus Tablet that used micro USB cable that was integrated into the charger.

Finally, as Lithium Ion batteries get old their internal resistance increases. This causes them to become harder to charge, a lot of energy is wasted in the form of heat. This is why old batteries get hot when they charge (new batteries can get warm too). This also causes them to die faster since their capacity is reduced. So the charger has to work twice as hard. You may have used a battery in a device once that had to stay plugged in or it would die immediately....thats just the extreme.

TL;DR : The reasons for this stuff are explained above but....

I would use a minimum of 5v/24amp chargers that actually produce it. Better bet would be USB chargers (18w+) with quality USB-C to lightning. USB-C cables typically do a good job because they were designed with charging at higher voltages and current in mind.

If you have a USB-C to lightning (and your Mac has USB-C), plug it into your Mac and goto About This Mac > System Report > USB > iPad and look for the amp draw (not sure how accurate that is but worth a peek).

You might just have a defective cable. It happens, Anker is good however they aren't without fault.

Battery might need to be replaced due to age.

Without tools to test this stuff there isn't a good way of knowing. The USB tester, load simulator, and lightning to USBC adapters I used above can all be found on Amazon. I work on electronics by trade so I obviously have an interested in this stuff....