I'm working 95% of my time with AC power and Thunderbolt Display. Since macbook pro retina's battery are no longer easily switchable I'm concerned about it's life and would like to maximize it. Before macbook retina I used to charge the battery to 50%, then after removing it I used the macbook without battery on AC power. But it's no longer possible.

I googled a little but didn't find a clear guidance about how to use your macbook mainly connected to AC power and not doing damage to your battery.

From what I know :

  • Full discharges should be avoided.
  • Keeping you battery charged to its maximum for too long time is also bad.
  • Try to keep charging cycles as low as possible. It's battery life (macbook pro retina battery is expected to keep 80% of its charge after 1000 charging cycles).

I try to disconnect AC power once a week until battery indicator goes down to approximatively 75% and then I connect back the AC to charge it to 100%. I don't know if it's the best steps to maximize the battery life but I think it's much better then to keep it all the time connected to the AC power.

What do you think. How to preserve battery life working on AC power ?


It's best to follow the guidance of Apple: http://www.apple.com/batteries/notebooks.html

Standard Maintenance

For proper maintenance of a lithium-based battery, it’s important to keep the electrons in it moving occasionally. Apple does not recommend leaving your portable plugged in all the time. An ideal use would be a commuter who uses her notebook on the train, then plugs it in at the office to charge. This keeps the battery juices flowing. If on the other hand, you use a desktop computer at work, and save a notebook for infrequent travel, Apple recommends charging and discharging its battery at least once per month. Need a reminder? Add an event to your desktop’s iCal. When your battery no longer holds sufficient charge to meet your needs, you may choose to replace it. If your notebook came with a built-in battery, you should have the battery replaced only by an Apple Authorized Service Provider.

Long-Term Storage

If you don’t plan on using your notebook for more than six months, Apple recommends that you store the battery with a 50% charge. If you store a battery when it’s fully discharged, it could fall into a deep discharge state, which renders it incapable of holding any charge. Conversely, if you store it fully charged for an extended period of time, the battery may experience some loss of battery capacity, meaning it will have a shorter life. Be sure to store your notebook and battery at the proper temperature. (See “Notebook Temperate Zone.”)

Basically what it says is use your Macbook in whichever way is comfortable to you. If you prefer to use it plugged into AC at all times, just make sure to disconnect it at least once per month and let it discharge to make sure the electrons moving around inside it.

Cycles are based on a cumulative basis. If you choose to let it go down to 50% twice, that's one cycle. If you chose to let it go down to 75% four times, that's still one cycle. The cycles will go with normal usage and you'll be much happier if you don't worry about it too much. The hardware is designed to last much of the life of the unit since the switch from Li-on batteries.

Contrary to your post, Apple DOES NOT recommend running laptops with removable batteries on AC without the battery: http://support.apple.com/kb/HT2332

Please check out this link from a less official, but still helpful source: http://forums.macrumors.com/showpost.php?p=9875442&postcount=23

  • However they don't say if it should be full discharge or just a partial one. – Tomasz Jaskuλa Aug 20 '12 at 20:50
  • 1
    It doesn't matter. Even if you drop it down to 80%, your still moving the electrons around. It's not like an HDD or a tape where not going to full empty will not touch that part of the item: discharging is discharging and it will help keep battery condition even if you run it for 30 minutes. AppleCare support, however, recommends that if you leave your Mac plugged in most of the time, unplug it every 2 or 3 days and run on battery down to somewhere around 50%, then plug it back in. That keeps the electrons moving at the best pace. – hiiambo Aug 20 '12 at 20:52
  • Thanks for your help. Just curious if you have any link to AppleCare support recommnadation about unpluging it every 2 or 3 day ? – Tomasz Jaskuλa Aug 21 '12 at 8:39
  • AppleCare doesn't put support up on the internet (otherwise, there'd be no reason to pay for it). You can certainly call them if you have AppleCare and ask. – hiiambo Aug 21 '12 at 14:43

Apple Says:

Charge your Apple lithium-ion battery whenever you want. There’s no need to let it discharge 100 per cent before recharging. Apple lithium-ion batteries work in charge cycles. You complete one charge cycle when you’ve used (discharged) an amount that equals 100 per cent of your battery’s capacity — but not necessarily all from one charge. For instance, you might use 75 per cent of your battery’s capacity one day, then recharge it fully overnight. If you use 25 per cent the next day, you will have discharged a total of 100 per cent, and the two days will add up to one charge cycle. It could take several days to complete a cycle. The capacity of any type of battery will diminish after a certain amount of recharging. With lithium-ion batteries, the capacity diminishes slightly with each complete charge cycle. Apple lithium-ion batteries are designed to hold at least 80 per cent of their original capacity for a high number of charge cycles, which varies depending on the product.

Compared with traditional battery technology, lithium-ion batteries charge faster, last longer and have a higher power density for more battery life in a lighter package. When you know a little about how they work, they can work that much better for you.

It charges fast for convenience and slow for longevity.

Your Apple lithium-ion battery uses fast charging to quickly reach 80 per cent of its capacity, then switches to slower trickle charging. The amount of time it takes to reach that first 80 per cent will vary depending on your settings and which device you’re charging. This combined process not only lets you get out and about sooner, it also extends the lifespan of your battery.


I asked Apple themselves and they told me that charge the Computer to 100% and then get it down as close as possible to 0% without it shutting down and then charge it back up and dont keep it plugged in, also you can close your laptop hence putting in sleep mode and not needing to shut it down.

  • That's not good for any Li-ion battery. It's an unavoidable feature of the chemistry. – Walf Aug 16 '17 at 0:37

A recent article on Wired suggested that you should unplug the charger once it gets to 80%, then use it until it gets to about 40%, then plug it in again and charge it until 80%, etc.

  • 1
    However, this article is not on Apple notebooks (which can make some difference for the topic discussed). – yurkennis Jul 3 '14 at 19:28

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