Macbook Air M4 Battery guidance

[madrich]

I previously had a MacBook Air Intel Core early 2015. It’s original battery lasted about 9 years! The way I handled my previous MBA was to let the battery run down to 80%-90%, and sometimes 100%, before recharging. I understand “now” that I should optimize charging and keep the battery limit at 80% and plugged in, as much as possible. However, I use my new Macbook Air M4 secondary to my other Apple devices (just like I did for my early 2015 Intel Core MBA.)

Would I still achieve similar battery longevity unplugged, but keep 80% battery limit?

Thank you for your comments.

 

[GGJstudios]

The best way is to simply run on battery when you need to and plug in when you need to. It will learn your habits and adjust accordingly.

 

[benholt]

9 years on the original cell is honestly not that wild for the 2015 Air — those Intel Airs ran cool and the shallow charge cycles you described aged the battery really gracefully. The good news on Apple Silicon is that the OS does most of that work for you now. Optimized Charging actually watches your routine and parks the charge at 80% until just before you typically need full capacity, even without you toggling the hard 80% cap on. The hard cap really shines when a laptop spends most of its life plugged in at a desk. For a secondary that sees more battery use than wall use, that cap mostly just shaves usable hours without buying you a meaningful lifespan boost. Heat is the bigger long-term killer at this point, so the one habit I'd actually carry over from your old MBA is not running heavy stuff on battery with the machine on a soft surface that blocks the vents.

 

[madrich]

9 years on the original cell is honestly not that wild for the 2015 Air — those Intel Airs ran cool and the shallow charge cycles you described aged the battery really gracefully. The good news on Apple Silicon is that the OS does most of that work for you now. Optimized Charging actually watches your routine and parks the charge at 80% until just before you typically need full capacity, even without you toggling the hard 80% cap on. The hard cap really shines when a laptop spends most of its life plugged in at a desk. For a secondary that sees more battery use than wall use, that cap mostly just shaves usable hours without buying you a meaningful lifespan boost. Heat is the bigger long-term killer at this point, so the one habit I'd actually carry over from your old MBA is not running heavy stuff on battery with the machine on a soft surface that blocks the vents.

Thank you for comment and explanation. When I sold my MBA AIR 2015 the buyer almost could not believe that I did not replace the battery and that the device was never repaired. Now, it’s a little hard to change my battery mindset. One mistake I made when I got my new MBA M4 was that I did not cleanup and delete unnecessary data on my old MBA before I migrated all of it to the new MBA. The migration seem to cause some data reorganization which helped me realize the junk I had on the old MBA. As I re-check my data libraries I am deleting files and recovering dara storage.

 

[triumvirate]

The best way is to simply run on battery when you need to and plug in when you need to. It will learn your habits and adjust accordingly.

Anecdote, but macOS never properly learned my habits and would let my past Macs live at 100% day in & day out. I’m extremely glad they finally added in the charge limits built-in. macOS seemed to “learn” only the most basic and unchanging routines for me. I noticed that if I kept a very strict routine it may have learned it after a week or more, but 1 small change would set everything back to living at 100% all day.

 

[Howard2k]

Anecdote, but macOS never properly learned my habits and would let my past Macs live at 100% day in & day out. I’m extremely glad they finally added in the charge limits built-in. macOS seemed to “learn” only the most basic and unchanging routines for me. I noticed that if I kept a very strict routine it may have learned it after a week or more, but 1 small change would set everything back to living at 100% all day.

My usage habits are not very predictable but it did work well for me and I found it was pretty regularly limiting to 80% with optimized charging. It probably took a couple of months before I started to notice it regularly working.

All the same, with Tahoe I do set the 80% limit to be sure.

 

[Technerd108]

Usage matters more than charging limits.

That bring said it is not a good idea to keep a laptop continuously plugged in over extended periods of time.

You want the battery to discharge to around 20% and to charge around 80%. Occasionally it is good to let the battery completely drain. Then completely recharge it. Maybe ever 6-12 months.

Heat is the other huge factor. You don't want to use fast charging all the time. Trickle charge is better for the battery and heat than fast charge. If you want to destroy a battery fast is fast charging in a hot environment.

So if you are using your MacBook plugged in don't use fast charging and use the lowest wattage and charging speed possible. You don't have to be crazy and if you like fast charging use it. Try to see if your device is getting warmer. If so, try to cool it.

Generally fast charging and leaving laptop plugged in all the time in combination with heat are the two biggest factors in battery degradation.

Apple now has some very nice granular controls to help preserve the battery.

This is a summary of my experience using lithium ion rechargeable batteries over a couple decades. I am no expert and could be wrong but I thought I would share my observations on the subject.