In-Depth iPhone Battery Experiment Pits Slow Charging Against Fast Charging

[Tsepz]

HTX Studio this week shared the results from a six-month battery test that compared how fast charging and slow charging can affect battery life over time.

Using six iPhone 12 models, the channel set up a system to drain the batteries from five percent and charge them to 100 percent over and over again. Three were fast charged, and three were slow charged.

Another set of iPhones underwent the same test, but with charging initiated at 30 percent and stopped at 80 percent, so the iPhones were always in that range.

Prior to the experiment, the capacity for each phone was tested, and after 500 cycles, the capacity was tested again. The results suggest there is minimal additional battery drain from fast charging, but keeping an iPhone between 30 and 80 percent charge could be minimally beneficial.

HTX Studio concluded that the best way to charge an iPhone is "however you like," without overthinking it and trading mental energy for a tiny bit of battery life. The same video also includes Android tests, and is well worth watching in full for those curious about the effects of fast charging.

Article Link: In-Depth iPhone Battery Experiment Pits Slow Charging Against Fast Charging

“HTX Studio concluded that the best way to charge an ‌iPhone‌ is "however you like," without overthinking it and trading mental energy for a tiny bit of battery life.”
I have been saying something similar for a while now, just not worth it to be so pedantic about charging.

 

[Motionblurrr]

I like how the guy in the video took 2 years to do this experiment and came to the conclusion that it’s a waste of mental energy and time to micromanage charging on smartphones, that had become popular on tech forums (especially this forum). The difference is negligible vs what people had been led to believe. 1-2% difference battery health at the end of the day? Lol.

And then you have some posters here that have never done any test like this, giving their 2 cents like they know better than the guy who did the experiment! “Yeah but it’s heat that kills the battery faster” “he needs more than 500 cycles to blah blah blah”. Lol absolutely ridiculous.

The writing is on the wall. It’s a waste of time. Just plug it in and charge to 100% if you want and need the phone to last you the maximum amount that day. Anything else and it’s just fake tinkering thinking you’re gaining something.

 

[jz0309]

Interesting... though I bet the posters who "baby" their batteries be it an iPhone or MacBook will continue doing what they've been doing, and that is totally fine, to each their own.
I'll continue to charge my devices to 100% on whatever use case u have. Electronics are a tool, and battery is a consumable in my book.
As I said, to each their own...

 

[filchermcurr]

I always find the reactions to this topic to be interesting. So many people dismiss the issue because they are in a position to replace the phone or battery when it becomes an issue. Unfortunately, a lot of people can't just pop into the Apple Store across the street and slap $100 on the counter. Either because they don't have $100, there isn't an Apple Store within a hundred miles, or both.

It's easy to get caught up in our little bubbles without considering that things may not be as easy for some people as they are for us. So if you can coax more life out of your phone by employing simple measures, I'm glad the information and capabilities are available for people who need to do that to be able to.

 

[seinman]

I need more independent tests. These are the recommendations for electric vehicle's (EV) lithium-ion batteries (same as smartphones, laptops, etc):

State of Charge
For daily driving, keep the charge between 20% and 80%. Charge to 100% only when necessary, such as before a long trip. This range reduces chemical stress and degradation on the battery's cells from very high or very low voltages.

Charging Speed
Use slower charging (Level 1 or Level 2) for daily use. Reserve DC fast charging (Level 3) for when you need to charge quickly, such as on a road trip. Slow charging generates less heat, which is a major factor in battery degradation. It is also less stressful on the battery's internal components.

Yeah, because a $50 low voltage battery that fits in your pocket has exactly the same performance and maintenance needs as a $10k high voltage EV pack. 🙄

 

[ikramerica]

My iPhone 13, approaching 4 years old, still has 89% capacity. I try to limit it to 80% charge using notifications, but I'm not religious about it. But even with a somewhat worn battery, 80% is still more than enough to get me through a typical day on this device.

Then why do you care if it’s 89% or 86% after 4 years? And years isn’t meaningful. Charge cycle count is meaningful.

 

[840quadra]

I have a 13Mini that I charged the hell out of and it has 84% battery. I’d consider trading in a device with full capacity to be a missed opportunity.

Okay, but exactly what does that have to do with preserving battery health? You are welcome to your opinion clearly. So maybe it was just that?

My cycle counts tend to be quite high every year, and I tend to do a ton of batch photo edits, and timeline critical 4K video editing on device for my clients. My clients also pay for fast turnaround, so I keep my devices fresh for the speed bumps that make a difference in my workflow. My use case, not yours.

Not that I need further validation for my business expenses, but I also enjoy new devices and often hand them down to family or sell to friends.

Either way, taking care of a device and battery keeps items from the landfill and reduces the need to manufacture new devices or battery cells.

For work (day job), I deal with 1 - 2 megawat blocks of UPS systems with various types of lithium batteries from Samsung, Toshiba and new Zinc technology from others. I am taking as much suggestions from these entities as I do from phone manufacturers on how to maintain battery health and warranty.

I’ll keep doing what I can to keep my cells in good shape.

 

[ikramerica]

Meanwhile, with my 13, I have a smart plug set up so it stops charging at 65% (don't need more that that, and I don't really have to "overthink" it, just plug and wait), same age as yours.. with a lower watt charger and through a cable, is at 94% so... well, it works for me.

Also I wonder if replacing a battery in a store is time consuming? Like how long do you have to be without your phone?

You have a lower cycle count. Cycles are counted by apple and equivalent to a full discharge and recharge. Your point being that you use your phone less and the battery is degraded less.

I drive my car less and my tires last for more years than other people. The solution for everyone who wants their tires to last more time is to drive fewer miles...

 

[ikramerica]

Apple has access to battery construction and design circuitry that we users don’t have. Maybe their battery on Apple Watch wasn’t as good as they claimed to be and they had to push the charging limit insanely hard to reduce warranty replacements?

Bulging bulging bulging

 

[ikramerica]

If you don't typically need more than 80%, it's not crippling, and it could extend the lifetime of the battery by 50% before you have to exchange it. That's not a small amount.

I see no evidence of your 50% longer battery life claim and you presented no evidence to support it.

Nobody is answering the cycle count question with their personal anecdotes.

But what we do know is some people say they keep the phone charging most of the time anyway and use it with a cable a lot at work and that means what? It means they don’t actually use their battery much and it’s why the health remained strong.

 

[LoveToMacRumors]

Dam, HTX Studio, I don’t think you guys know just how popular he is in China

 

[Reason077]

Then why do you care if it’s 89% or 86% after 4 years? And years isn’t meaningful. Charge cycle count is meaningful.

Based on past experience, my previous iPhones were often much worse than 86% after 3-4 years. Often with a failing battery that had a risk of sudden shutdowns when you got below 20% or so.

 

[Reason077]

Total waste of time. Negligible difference that no one will ever care about. Ever.

In my experience it seems to have made a significant difference. My previous iPhones all had terrible batteries at this age.

 

[Reason077]

I need more independent tests. These are the recommendations for electric vehicle's (EV) lithium-ion batteries (same as smartphones, laptops, etc):

Yes, and this isn’t just a third party recommendation. The manufacturers themselves recommend an 80% limit for daily charging. It’s built in to the software to remind you.

But notably this only applies to batteries with NMC and similar chemistry. Lithium Iron Phosphate (LFP) batteries, which are becoming more common in EVs, can be charged to 100% every time without significant degradation.

 

[D_J]

I use 80% limit on my 15. I live in Airplane Mode (no cellular service here and depend on WiFi calling), and get 2+ days of battery life. Have had the phone over 18 months and sitting at 99% battery health (197 charging cycles). I do set charging to 100% when traveling. ¯\_(ツ)_/¯, it works for me.

 

[Reason077]

My ipad 2 (year 2011) still has a month of standby - wifi off, everything off, I only use it as a timer.

Yes, great batteries in the iPad 2. Mine is still doing pretty good too after 14 years!

 

[I7guy]

I needed to go to the emergency room at the hospital one night with my son. Took my iPhone and AirPods off the charger.

Once I got there and my son was admitted, I started calling and texting friends and family.

I quickly noticed that my battery was a bit under 80% on both devices, realising it was the ”optimised charging” in effect keeping my state of charge at 80% ”until I need them”. Turns out the only time all year that I really needed 100% charge, the phone didn’t know I needed a full charge, and that’s because there is no such thing as artificial intelligence. 🤖

That was when I turned that function off forever. I will never trade a fully charged battery against battery health longevity. And you know what? I can’t discern any notable difference in battery health. It’s the same.

And my son was fine in the end. ☺️

Glad everything turned out okay. However in my cars plenty of charging solutions. Small battery pack with the usual assortment of cables and what not.

Yeah, because a $50 low voltage battery that fits in your pocket has exactly the same performance and maintenance needs as a $10k high voltage EV pack. 🙄

Li-ion chemistry as you know behaves the same across applications. They all chemically age. However the ev application has sophisticated management systems to keep the batteries in service as long as possible.

I see no evidence of your 50% longer battery life claim and you presented no evidence to support it.

Nobody is answering the cycle count question with their personal anecdotes.

But what we do know is some people say they keep the phone charging most of the time anyway and use it with a cable a lot at work and that means what? It means they don’t actually use their battery much and it’s why the health remained strong.

Battery health of li-ion degrades chemically with age. Can’t stop it.

 

[klasma]

I see no evidence of your 50% longer battery life claim and you presented no evidence to support it.

Since the wording is ambiguous, let me clarify that I was talking about long-term battery life (battery degradation), for example how long it takes for maximum battery life to drop to 80%. The YouTube video reported on by the MacRumors article shows that after a year and a half, the 30-80% iPhone’s maximum battery capacity dropped only by 8%, compared to the 5-100% iPhone’s maximum battery capacity that dropped by 12%. Extrapolating, this suggests that the 30-80% iPhone would take 50% longer to drop by 12% than the 5-100% iPhone did. Of course, battery degradation isn’t completely linear, so it might be a bit more or a bit less. I’d be happy to see data that brings more precision here.

 

[sleeptodream]

You can limit MacBook using AlDente.

It’s sad we still have to resort to that on MacBooks 🫤

 

[SebCohen]

A thought…if Apple recommends only charging to 80% because 100% degrades the battery too much, they shouldn’t be allowed to advertise the 100% battery level and it’s duration on a full charge as the amount of battery available to charge.

 

[JohannesO]

When an iPhone is turned off, does it charge in the same way as when it is turned on?

 

[DougiePhresh]

I don’t understand when people religiously keep their phone battery between 30% and 80%. They do it under the pretense that it is better for their battery and makes it last longer - but if they are only ever using 50% of their battery anyway … you could cycle a battery 2,000 times before it gets anywhere near 50% capacity. It just makes no sense why people would put so much effort into preserving battery life when they don’t ever even use 1/2 of it anyway

 

[I7guy]

A thought…if Apple recommends only charging to 80% because 100% degrades the battery too much, they shouldn’t be allowed to advertise the 100% battery level and it’s duration on a full charge as the amount of battery available to charge.

But that should be across the board with batteries using the same chemistries. Because all manufacturers that use this battery suffer from the same limitation of potential battery degradation.

 

[I7guy]

I don’t understand when people religiously keep their phone battery between 30% and 80%. They do it under the pretense that it is better for their battery and makes it last longer - but if they are only ever using 50% of their battery anyway … you could cycle a battery 2,000 times before it gets anywhere near 50% capacity. It just makes no sense why people would put so much effort into preserving battery life when they don’t ever even use 1/2 of it anyway

It has to with the documented behaviors of li-ion batteries. It may not make much of a difference with an $89 iPhone battery, but on a $15,000 ev battery it can make a difference.

 

[code-m]

I sell my phone every 2-4 years and offsetting by charging to 80% make the device more financially lucrative for trade-in/resale value without having to take a financial hit.

Been charging my iPhone 16 Pro to 80% since Day 01 with the few instance to charge to 100% due to battery calibration and 14 months later it’s at 100% with low recharge cycles. Using the device without restrictions.

This test jus proves that charging to 80% is offsetting the remaining capacity; big revelation 😒