Apple MacBook (Air/Pro) batteries – The 2021 explanation

Apple always tries to stay ahead of the competition with its battery technology. They were one of the first companies who pushed the cycles from their batteries from 300 to 1000. They also changed from cylindered style cells to block shapes in their laptops. To get more capacity in the same space. The users could now even work longer on their battery. In the last years, Apple has introduced two new features that will lower the battery capacity. What’s going on? 

Laptop batteries are made of many separate rechargeable cells based on lithium-ion technology. Every cell is a small bag with chemicals. Build with carefully formed formulas to put as much energy as possible in the smallest and lightest form. Often bought from the cheapest supplier that meets Apple’s standards. 

When you charge or discharge the cell, the chemicals will do their work. The problem is that they always wear out a little bit. Charging and discharging will put stress on the cells. This stress is the highest when the cell is almost full or almost empty. It isn’t a coincidence that a new device out-of-the-box has a 40 percent charge. This is the most stable charge to keep a battery healthy for a long duration. If you keep your battery between 20 and 80 percent, it will stay healthy for years.   

Apple says its batteries are rated for 1000 cycles before the battery reaches 80 percent capacity. However, the chemicals used in lithium batteries are unstable. The batteries will still lose health over the years. In other words, Even if you don’t use your battery, the slow degradation of the chemicals will cause lower overall capacity over time. 

Doesn’t matter what you do. Each lithium battery will reach a point when it’s completely worn out. This can happen in one year. This also can take ten years. There is a trick by storing the battery in a fridge to extend its lifetime. But in my eyes, that isn’t a viable solution.

Apple’s Health longevity battery mode

In 2020 Apple introduced a new feature with its macOS 10.15.5 (Catalina) update. They wrote this in the changelog : 

Battery Health Management

  •  Battery health management to help maximize battery lifespan for Mac notebooks
  •  Energy Saver preference pane now displays battery condition and recommends if the battery needs to be serviced
  •  Option to disable battery health management

 For more information, please visit https://support.apple.com/kb/HT211094.

I’m using an Intel Macbook Pro 2020 as my daily computer. In the last 17 months, this laptop has completed 76 cycles on its battery. This is one cycle every week. In English: I seldom use this notebook on battery power. It is a no-brainer that I have enabled “manage battery longevity” mode in the Battery preference. Within weeks the health of my battery was brought down from 100 percent to 85 percent. For the last 17 months, the health stayed stable at this number. The cells are healthy. But they won’t be fully charged. Hence, they encounter less stress.

I personally think that the battery longevity mode is a brilliant solution to extend the battery’s life. Why? This is an assumption. I haven’t found a source for this. My hunch is: Every MacBook battery has a small microcontroller that manages the safety and charging of the cells. macOS reprograms the capacity values in the microcontroller. This trick makes it possible that the battery longevity can work independently of the operating system. Even when the notebook is powered off and charging. Or if the user runs another operating system with the help of Bootcamp. I need to test this theory. I need to swap out the battery with another MacBook to see if the battery shows the same numbers.

On Facebook, I was active in a few groups about Apple Macbooks. A couple of times a week, the same question appeared in the groups: “My new MacBook already has a lower battery health.” Apple enables the battery longevity mode by default on new laptops. And the Apple Silicon machines (M1, M1 Pro, and the M1 max) don’t even have the option to disable the battery longevity mode. 

The same kind of reaction was coming back in the comments. “Your MacBook has a failing battery. return to the Apple store”. In most cases, I don’t think the battery is failing. This is Apple moving in mysterious ways. The battery longevity mode is responsible for this lower capacity. 

It was time for an experiment. I want to know the actual capacity of the battery in the MacBook on my desk. And I need to collect information for this blog post. The battery pack was manufactured on Monday, 16 March 2020. Almost 21 months ago.

Battery capacity on Sunday 5 December 2021

Turn off the battery longevity mode in macOS 12 Monterey

Battery capacity on Wednesday 8 December 2021

It took three days to show the actual capacity of my battery. To be sure, I cycle the MacBook through a complete battery recalibration process. The battery capacity was now 96,5 percent. In the 21 months, this battery has lost 3,5 percent of its total capacity. Not bad for the hostile environment where I live. Did I mention that the average temperature in this room is always around 30 degrees Celcius? 

The battery longevity mode can cause some controversy. This function has taken away the only way for an Apple Silicon user to check if their battery is still healthy. How can Apple Silicon users check the capacity of their MacBook battery? They can’t disable the battery longevity mode. If a user sees on his new notebook low battery health. Is this the battery longevity mode at work, or can this mean that the user has a faulty battery? What if customers visit the apple store with a malfunctioning battery. The Apple employee can now claim it is the longevity mode causing the low capacity. But then the battery dies just after the warranty expires. Apple took away the method to check if your batteries are still OK. I think Apple should give the Apple Silicon users the option to disable the battery longevity mode. Do you agree? 

Optimized battery charging

The second feature introduced by Apple to help to reduce the stress on your battery is the “Optimized battery charging” function. First introduced in macOS 11.0 Big Sur. Apple claims that this feature works by predicting when you will use your MacBook on battery power and when you are using your MacBook on battery power? The moment you are using your MacBook on wall power, the battery will not be charged beyond 80 percent. 

If you’re using your MacBook every day from 9:00 till 12:00 on battery power. Around 8:00, the MacBook will charge the last 20 percent to give you a 100 percent full battery at 9:00. My battery stays at 80 percent all the time. This is because I’m hardly using the MacBook on battery power. To be honest. I don’t need Apple to decide when to keep my battery at 80 percent charge. Give me the option to keep my battery always at 80 percent charge. I don’t need machine learning for this. There are third-party tools that can do that work for me. I can even keep my battery at a 40 percent charge. 

What does this mean for my machine? 

The combination of longevity battery mode and Optimized battery charging keeps my battery all the time at a much lower charge. 

  • Design capacity : 5100Mah
  • longevity battery mode: 5100 – 15% = 4335 Mah
  • Optimized battery charging 4335 – 20% = 3470 Mah

It’s too early to have any conclusion about those two features. Maybe in one year, I will write an angry blog post about how the MacBook Pro battery only lasted two years. But at this moment, I’m impressed that I only lost 3,5 percent battery health since July 2020. 

This could save me a lot of trouble in the past

If Apple had introduced those two features years ago. It would have saved me money and a lot of hassle. I wrote on my blog about my previous MacBook Pro batteries. I assume that those batteries got problems because they were kept 24/7 at a 100 percent charge in a warm environment. On regular days, it is around 30 degrees Celcius. On some days, this room can reach temperatures over 35 degrees Celcius.

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