Can someone clarify this about cycles/battery?

[JoeyK]

Hi,
Just to make sure I understand charging/cycles of MBA correctly. Say my computer is at 100%, and I use it down to 90% - do I need to charge it from 90% to 100% 10 times for it to count as one cycle, as it's charging 10% each time?

 

[gnasher729]

Yes, exactly that. Going from 100% to 0% = 1 charge. Going from 100% to 90% = 1 tenth of a charge.

If your laptop is plugged in _all_ the time, the best for battery health is to unplug it and use it down to 0% maybe once a month. Not more often. And the rest of the time leave it plugged in. Of course if you don't use it at a desk, that's fine as well.

 

[flaubert]

I would amend gnasher729's advice to say run it down periodically, but never very close to 0%. Lithium batteries don't recover well from being run down to zero. For instance, my Toyota Camry Hybrid has a lithium battery, and I notice that Toyota's algorithm maintains the battery state of charge between about 25% and 90% at all times.

There is an app that you can use to help manage your battery life called FruitJuice:

FruitJuice — battery maintenance app for Apple Mac laptop computers.

FruitJuice helps you keep your Apple Mac Laptop battery running and lasting longer.

fruitjuiceapp.com

 

[thasan]

Don’t think doing 0% is a good idea. In reality the electrodes ‘breathe in and out’ during charging and discharging. This damages the material structure, leading to a gradual loss in capacity. It is therefore better to keep the charge discharge away from 0%. For 100% the mechanism is slightly different but results in gradual loss of capacity.
im also unsure about 10% being counted as 1/10th of a cycle. I work on battery research and never heard of a metric like that. cycles For battery are typically defined between full charge-discharge.