If you have an old phone and an old battery, is it possible to perform a factory reset so that Settings -> Battery -> iPhone Battery Health shows 100%?
The background/original question text is below this line. Additionally, here is a link to a more detailed question about a treasure trove of advanced data I discovered, as well as a more general electronics question about how to measure cellphone battery charge and health.
This is another very important background for the iPhone 11. It may indicate that the factory reset trick triggers iOS 14 and later (mine is 16) to recalibrate battery health, which takes “a few weeks” while showing health as 100% with an asterisk footnote, It means the real value will come in a few weeks.
In my shopping mecca of South America, there are
countless iPhones for sale in many stores. They have a certain grade, new in a sealed box, then used, then used. Large collection of original scratch free phones.
But someone was clearly playing a prank. On the surface, Apple iOS 16 should tell us when a non-genuine part replacement has occurred, but there’s a way around it, isn’t there?
Especially the battery life issue. So they sell 100% iPhone batteries and claim these batteries are replacement batteries, but they say the batteries are original from the US, not from China. The whole theme of “China” vs. “America” is important here.
I’m not an Apple iPhone user, but I want to make my girlfriend happy. So I tried to navigate the cliff. Checked there were no non-genuine warnings there, checked the serial number (had returned one to the store and the serial number said “returned”. So now I have one with a clear serial number – not covered by warranty of course).
But I’m doing a battery test. Just check YouTube on the website to see how quickly 100% battery drains. And it goes a little too fast for my taste. After about 2 hours, the battery reached 40%.
When I looked more closely at the 100% battery health information, I read the fine print telling me that it was recalibrating and that it would take weeks instead of days to actually get results. So that tells me they’re playing a trick on me I’m now figuring out how simple this trick is. It looks like every time you do a factory reset, the battery history is lost and the battery health message doesn’t say “Unknown” but “100%”.
Have I been cheated? I feel like I could go back to the store, I don’t know if they will refund me or what I will do with the money, buy a phone with 93% battery life? So do they have other scams ?
Anyway, I need some hard facts to prove them wrong. I’m trying to run some deep discharge and charge cycles to get battery health information for some evaluation. Or should I use some app to get a better assessment faster? They told me I had a 40 day warranty and would hopefully have the issue resolved within the next few days to avoid unnecessary travel.
From an electronics perspective, I find it surprising that we don’t just have an amp meter that just integrates the amps over time for charging and discharging and tells us the instantaneous milliamperes of a discharge-charge cycle time value. vs the Chinese statement is wrong. All iPhone batteries are assembled in China from parts produced in other countries in Southeast Asia. [Some production may be moved to India in the future].
The iPhone 11 is 4 years old, so even if it has the original iPhone 11 battery and the new battery has not been used, it is long past its prime. For iPhone 11 battery replacement, it always takes some time to calibrate the new battery in the device since you can’t tell its lifespan in a single “snapshot.” In addition to the phone itself, coconut batteries may give you a “second opinion.”
Here’s some hard data on lithium-ion battery life – Battery University – BU-808: How to Extend Lithium-Ion Batteries It’s aimed at the laptop market, but the exact same degradation occurs in iPhone 11 cell phone batteries.