After only 3 years and 80 charge cycles, the battery health of my $4,500 MacBook Pro is at 78%. The reason for this degradation is well documented in scientific literature; Lithium-ion (Li-ion) batteries degrade faster at higher cell voltages [1]. This is why vehicle manufacturers recommend keeping EVs stored at a lower percentage and only charging to 100% for longer trips [2]. This approach can allow Li-ion batteries to retain 80% of their original capacity after 15 years [3] – significantly longer than the 3 years it took my battery to degrade the same amount.

Sadly, for portable devices that spend most of their life plugged into a charger (impossible to avoid when using an external monitor), Apple keeps the device at 100% charge which drastically accelerates ageing of the battery.

As a result, batteries often don’t last the life of the device. Many people on certain opinionated forums state that the convenience of always having a fully charged battery outweighs the cost of replacing the battery. But the problem isn’t only financial. It’s also the environmental waste generated by billions of batteries that don’t last the life of the device, not because they can’t, but because the device is designed in such a way that battery longevity is severely sacrificed in favour of maximum short-term capacity, even if the user never requires the full capacity of the battery. And yes, it is waste because batteries are not widely recycled; 95% end up in landfill [4].

Apple offers a feature called Optimised Battery Charging which is designed to somewhat combat this problem by holding the battery at 80% until a full charge is required. However, this feature simply doesn’t work for machines that spend extended periods of time connected to a charger. In my case, only very occasionally have I seen the charge held at 80%. Most of the time the charge is held at 100% despite not once in its entire lifetime has my machine ever required a fully charged battery. My armchair guess is that without a charging routine, the algorithm gets confused and errs on the side of caution by giving the device a full charge. I’ve found Optimised Battery Charging only works with consistent charge/discharge cycles, for example a phone that’s put on charge at the same time every night. Again, this just isn’t possible if you’re using a portable machine like a desktop which is virtually every software engineer I know.

Most laptop manufacturers – as well as many smartphone manufacturers – allow the user to set a maximum charge percentage which the device will not exceed even if left on the charger for extended periods of time. If the user doesn’t need the full capacity of the battery, lowering the maximum charge percentage can drastically improve its life; reducing the maximum charge to 80% results in 2-3x increase in longevity [5]. Apple on the other hand offers no such option, instead opting for Optimised Battery Charging which delays – but doesn’t prevent – the battery from reaching high charge levels and requires extremely specific and consistent user behaviour to function at all.

This is where AlDente comes in. AlDente allows the user to set maximum charge and drift percentages, as well as the ability to discharge and calibrate (which can cycle the battery while plugged in). I’ve been using this app for a few months now and it works great, probably the best $30 I’ve ever spent. My only regret is not purchasing it sooner. When applied to a new device, AlDente should be able to prolong the battery to the point that it outlasts the device. AlDente works on both Intel and Apple silicone Macs.

This post is in no way affiliated with AlDente or AppHouseKitchen – I’m just a happy user of the product.

[1] Battery University. 2021. BU-808b: What Causes Li-ion to Die?. https://batteryuniversity.com/article/bu-808b-what-causes-li-ion-to-die

[2] Autovolt. 2020. How to park your EV for long periods: manufacturer guidance. https://www.autovolt-magazine.com/how-to-park-your-ev-for-long-periods-manufacturer-guidance/

[3] California Air Resources Board. 2021. Advanced Clean Cars (ACC) II Workshop, (slide 79). https://ww2.arb.ca.gov/sites/default/files/2021-05/acc2_workshop_slides_may062021_ac.pdf

[4] Chemical & Engineering News. 2019. It’s time to get serious about recycling lithium-ion batteries. https://cen.acs.org/materials/energy-storage/time-serious-recycling-lithium/97/i28

[5] Battery University. 2021. BU-808: How to Prolong Lithium-based Batteries. https://batteryuniversity.com/article/bu-808-how-to-prolong-lithium-based-batteries