Disclaimer
We are not chemists, electrical engineers, or any other form of battery experts. This post is a direct response to requests for information. We’ve researched the questions we most commonly receive about Apple Laptop Batteries and condensed the results into a short post. With that in mind, we lead with our sources, to encourage further research. This information is only applicable to Lithium Ion batteries used in all current and recent Apple laptops.
Sources
Conclusions
Go through at least one discharge cycle per month.
It does not matter if this is one full cycle at one time, or multiple partial cycles spread out throughout the month.
Calibrate the battery once a month.
This will improve the accuracy of the power meter in the menu bar, not the capacity of the battery. Calibration instructions.
Avoid storing batteries that are fully discharged.
If at all possible change to another battery before it is fully discharged.
Avoid storing fully-charged batteries in a hot place.
Leaving a fully charged battery in a hot car will reduce its capacity. This includes a fully charged battery in your computer. Removing the battery from a plugged-in computer is one option, but has severe drawbacks (imagine working on an important file when your mag-safe power adapter is pulled loose). Though not found in the sources, we note that a less extreme option is to raise the minimum speed of your internal fan using SMC Fan Control (Intel-Based Laptops only). This will keep your laptop cooler and should reduce the effect of heat on the maximum capacity of the battery. The effect of this program on the longevity of the internal fan is not known, but it has been running on one of our 17″ MacBookPros for two years.
For long term storage charge the battery to about half charge.
Apple recommends 50%, Cadex recommends 40%. The universal agreement is that storing batteries fully charged or fully depleted is a bad idea. Storage temperatures between room temperature and refrigerator temperature are acceptable. Freezing is not recommended.
Your battery should hold 80% of its original capacity for 300 charge cycles, but will drop quickly thereafter.
The drop in capacity is much faster after 300 cycles than before (capacity vs time is a downward curve). You can find the number of cycles by Apple > About-This-Mac > Power. You can also use Coconut Battery for a more user-friendly readout.
If your battery is dying prematurely Apple may replace it under warranty.
If your capacity is shot and you are not yet to 300 cycles take your computer to the Apple Store and ask if they can replace your battery. According to forum discussions the resulting compensation will vary from nothing to a free on-the-spot replacement.
Li-Ion Batteries have a shelf life regardless of storage method.
Cadex references 3 years as a normal shelf life but confirmation could not be found in other sources.