Surprisingly simple way to extend MacBook battery life
A lot of our devices today runs on lithium ion batteries. This, of course, includes the MacBook and therefore the ongoing pursuit to find out how best to extend the MacBook battery life. Most of us now know that its not good to always keep devices with lithium-based batteries to be constantly charged. But what if you use your MacBook like a desktop, especially now when we are mostly working from home?
Why we need to do more to extend the MacBook’s battery life?
Apple actually does a pretty good job at keeping the batteries as healthy as possible when compared to other brands. They even have a guide on how to calibrate the Macbook batteries. Recent MacOS updates has also introduced the optimised charging to improve the MacBook’s battery health. The following bits of information at Battery University explains why.
The worst situation is keeping a fully charged battery at elevated temperatures. Battery packs do not die suddenly, but the runtime gradually shortens as the capacity fadesSource: https://batteryuniversity.com/learn/article/how_to_prolong_lithium_based_batteries
A laptop battery could be prolonged by lowering the charge voltage when connected to the AC grid. To make this feature user-friendly, a device should feature a “Long Life” mode that keeps the battery at 4.05V/cell and offers a SoC of about 80 percent. One hour before traveling, the user requests the “Full Capacity” mode to bring the charge to 4.20V/cell.Source: https://batteryuniversity.com/learn/article/how_to_prolong_lithium_based_batteries
However, I’ve had to replace my few of my MacBooks’s batteries due to bloating. Again, Battery University is a great source on explaining why this is the case.
When overcharged, a battery gases, splitting water in the electrolyte into hydrogen and oxygen.Source: https://batteryuniversity.com/learn/article/bu_803c_loss_of_electrolyte
What can we do to extend the battery lifespan
Battery University continues to be a really good source of information.
Avoid deep cycling. Each cycle wears the battery down by a small amount and a partial discharge is better than a full discharge… Li-ion is maintenance-free and the battery lasts longest when operating between 30 and 80 percent SoC.
Partial charge better than a full chargeSource: https://batteryuniversity.com/learn/article/how_to_charge_when_to_charge_table
Therefore, here are the two simple steps to extend your MacBook battery life.
1. Enable MacOS battery health management
The MacOS settings to enable it to manage battery longevity should be enabled by default. But check it anyway. By the way, if you’re using an M1-based MacBook, you will not be able to find this settings. I suspect that its enabled permanently.
If you use your MacBook mostly mobile, this setting alone is sufficient. But if you are using your MacBook like a desktop like me, then read on to the next step.
2. Limit the MacBook charge to 80% maximum
I use an app called AlDente to do this. You can download the app from the link here. The app works perfectly on macOS Big Sur too. Installation of the app should be straight forward. The app’s readme page at GitHub explains the detailed steps if you need it.
Once you set maximum battery charge at 80%, just click exit. AlDente should already have set the MacBook’s SMC (System Management Controller) to only charge up to the level you’ve set. Reboot your MacBook for the settings to take effect.
If your MacBook had more than 80% of battery life, you will need to drain it below 80% first.
I will be updating this post perhaps in a year or so to see how well this trick works out for me. As I just had the battery replaced not too long ago, this would be a perfect way to test the effectiveness of setting the 80% max charge level.
So, as a record, as of 23 Dec 2020 my MacBook current holds a full charge capacity of 6676mAh. I will come back and test it 6 months ahead and again at the one year mark.
2 years later…
A reader reminded me just the other day that I had not updated this post as I said I would. Better late than never, here is the current state of the battery 1189 days old.
Today, it stands at 94% of its designed capacity. Notice that it only gone through 24 load cycles as its almost constantly plugged in via the eGPU enclosure.
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