You do not need to disconnect your MacBook Pro's battery. Your battery will stop charging once it is full. Apple's modern batteries are much smarter than previous designs.
To get the most out of your MacBook Pro's battery, follow the Notebook Battery advice from Apple: unplug and use your battery until empty about once a month, then charge back up to full.
At the time of answering, Apple's advice read:
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 you need help following Apple's advice, use Battery Guardian; it is free and will remind you when to deplete your battery.
Final Conclusion
Given the sources and explanations below. I am officially going to do the following to optimize my battery life:
- Keep my battery as cool as possible.
- Don't worry about whether it's plugged in or not. When it doubt, keep it plugged in so it uses AC power instead of battery, unless getting hot.
It turns out that the two methods I originally posited are largely moot. The only thing that really matters is temperature.
"Temperature was the most significant factor contributing to the cell degradation, with state-of-charge (SOC) and discharge pulse length of secondary importance." (Liaw et al.2)
Furthermore, it turns out that the decay can be accurately mathematically modeled:
(See Ramadass et al.1 for explanation of terms)
However, the dominant model is that of the Arrhenius formula, which generically predicts time-to-failure as a function of temperature.
The figure below shows the capacity at various cycle counts. Just look at the capacity on the x-axis. The top graph is at 25ºC, the bottom at 50ºC.
After 600 cycles, the cooler battery had ~2x the capacity
While I could still find no evidence on the behavior of Mac power circuitry, there was helpful information on the official Dell website. Two items specifically stood out.
Q. When docked or AC adapter is plugged into a wall outlet, am I using my battery charge?
A. No.
http://www.dell.com/content/topics/global.aspx/batteries_sitelet/en/batteries_faq?c=us&l=en&cs=19#faq9
Q. Should I totally discharge, then recharge my Dell laptop battery occasionally to make it last longer?
A. No, discharging and charging does not increase the life of a Lithium Ion technology battery.
http://www.dell.com/content/topics/global.aspx/batteries_sitelet/en/batteries_faq?c=us&l=en&cs=19#faq27
However It is important to note that Apple and Dell charging circuits may be different. Although, given that Dell does this, I assume apple does as well. On this assumption, unless someone can provide sources to claim otherwise, I will assume that the Apple charging circuitry is smart enough to know this.
I encourage anyone to continue exploring this question and challenge my assumptions. Please see the sources below if you're curious for a more detailed explanation.
Sources
1 Ramadass, P., Bala Haran, Ralph White, and Branko Popov. "Mathematical Modeling of the Capacity Fade of Li-ion Cells." Journal of Power Sources 123.2 (2003): 230-40. Web. http://www.che.sc.edu/faculty/popov/drbnp/WebSite/Publications_PDFs/Web33.pdf.
2 Liaw, B., R. Jungst, G. Nagasubramanian, H. Case, and D. Doughty. "Modeling Capacity Fade in Lithium-ion Cells." Journal of Power Sources 140.1 (2005): 157-61. Web. http://electrochem.org/dl/ma/204/pdfs/0253.PDF.
[3] Ning, G. "Capacity Fade Study of Lithium-ion Batteries Cycled at High Discharge Rates." Journal of Power Sources 117.1-2 (2003): 160-69. Web. http://www.che.sc.edu/faculty/popov/drbnp/website/Publications_PDFs/Web38.pdf.
[4] Ramadass, P., Bala Haran, Parthasarathy M. Gomadam, Ralph White, and Branko N. Popov. "Development of First Principles Capacity Fade Model for Li-Ion Cells." Journal of The Electrochemical Society 151.2 (2004): A196. Web. http://www.che.sc.edu/faculty/popov/Publications/Premanand1.pdf
[5] Zhang, D., B. S. Haran, A. Durairajan, R. W. White, Y. Podrazhansky, and B. N. Popov. "Studies on Capacity Fade of Lithium-ion Batteries." Journal of Power Sources 91 (2000): 122-29. Web. http://www.che.sc.edu/faculty/white/2000studiesoncapcaityfadeofzhangharandurairajanwhitepodrazhanshkypopov.pdf.
Best Answer
"I know I should run the battery calibration check and also have the battery down to 10% once a month."
Apple actually recommends fully charging and then discharging the battery once per month. All modern Macs with batteries self-calibrate and require very little user involvement. There is no best practice as to what level to charge a battery at, none that I have seen that equate to a significant elongation in lifespan.
In short, use your MacBook Pro and don't worry about its battery. Ideally, as long as you are depleting and recharging it, then the battery's health should remain optimal. Running a notebook that is always connected to a power supply is not ideal. Battery cells like it when the electrons flow; unfortunately it is that very motion that invariably leads to a reduction in charge capacity. That is just the nature of the technology. Damned if you do, damned if you don't.
A partial charge is just that: when a battery is recharged without being fully depleted. Apple rates batteries based on full charge cycles. So if you would let yours run down to 50% and then recharge it, twice, then you would have hit one full charge. There is no relevance as to the health of the battery should you recharge it at any given point. Recharge it when it's convenient for you.
The main culprits to poor battery health are heat and inhibiting the movement of electrons (by keeping the notebook plugged in all the time). Avoid those and your's will be just fine.
You can consult Apple's suggestions on the matter.