Battery percentage, how accurate?

[Peter Franks]

I presume this is probably quite common, but wondered anyway....

I had it with the 5S and assumed it was an age thing, because the phone was old, but the new 8 does the same, If I take it off a charge a few percent prior to 100%, and turn it off before bed, it will always show 100 when switched on the next day. Is there a reason for that jump, or just one of those things. Makes you wonder about the accuracy of readings.

 

[Minho]

Those readings are given directly by the battery. Modern batteries have gas gauge IC's and circuitry built-in. The numbers they will give you are as good you can get. All of those apps and software solutions are just reading what the battery "publishes", there is no interpretation.

The other thing to consider is that batteries are a chemical process. It's quite possible that the battery is rebounding or adjusting to charge, in a manner of speaking. The fact that you shut down the phone forces the gas gauge circuitry to re-evaluate the battery when you power it back on.

 

[Peter Franks]

Thanks for your reply!

 

[Tresbubu]

so my battery that in 8 hours of airplane mode loses 4% is to be considered a battery defect ?!

 

[Mlrollin91]

so my battery that in 8 hours of airplane mode loses 4% is to be considered a battery defect ?!

No, batteries discharge based on dozens, if not hundreds of variables.
[doublepost=1536615553][/doublepost]

I presume this is probably quite common, but wondered anyway....

I had it with the 5S and assumed it was an age thing, because the phone was old, but the new 8 does the same, If I take it off a charge a few percent prior to 100%, and turn it off before bed, it will always show 100 when switched on the next day. Is there a reason for that jump, or just one of those things. Makes you wonder about the accuracy of readings.

Check out this post, this is how iOS reads batteries.

https://forums.macrumors.com/threads/battery-health.2132141/#post-26342835


"As to your 100% for 30+ minutes. Thats because the battery meter is not linear for the first 5%. The battery meter will not start moving until the phone's battery is actually at 95%. It works like this:

100% Reported = 95-100% actual.
50% Reported = 47.5% actual.
10% Reported = 9.5% actual.
1% Reported = 1% actual.

The reason it does this is because the phone stops charging once the battery itself hits 100% (not the meter). It will then discharge until it hits 97% (actual, not meter) and will then begin to recharge. By making the phone meter not move until it hits 95% actual, it prevents consumers from freaking out why their phone is discharging while its plugged in. Its just easier to use the above "formula"."

 

[Resist]

You also should be calibrating the battery monthly and after every iOS update.

 

[Peter Franks]

If you’re talking to me, I’ve only just got the ‘8’, and it’s saying 100 when it’s charged to 97. But with this type of battery I keep reading that Apple says that type of battery doesn’t need calibrating.