I’m on my third battery for my 2007 Apple 15″ MacBook Pro. The first two, thankfully covered by AppleCare, were replaced after their maximum capacity slowly reduced to unusable levels (10–20% of original capacity, 30 minutes or less of run time). Supposedly, these lithium-based batteries do not develop a “memory” from charging cycles, but something i had been doing with those first two batteries caused dramatic loss of capacity after less than a year.

I came across an article at BatteryUniversity.com called How prolong lithium-based batteries just as my second battery was needing replacement. I decided to try changing how i used and maintained the next battery.

A New Strategy

And after 4 months it appears to be working. coconutBattery reports this third battery is only down 5% from its original capacity. The last battery was already down 12% after the same period. So what have i been doing differently? Not using it. I literally take it out of my MacBook Pro and set it aside. I know the newer “unibody” MacBook Pros don’t have removable batteries, so some of this won’t apply.

Why?

The worst condition is keeping a fully charged battery at elevated temperatures, which is the case with running laptop batteries.

Numbers in that Battery University article show that high temperatures coupled with a fully-charged battery accelerate capacity loss. Basically, if you leave your notebook plugged in all the time (like i do, using it as a desktop replacement), you’re more or less cooking your battery to death.

Apple does not recommend leaving your portable plugged in all the time.

Battery University suggests to do partial charge/recharges rather than full drains, as well as a maintenance calibration of a full discharge and recharge every 30 cycles (every month or so). Keep the battery at half charge for long-term storage. Apple recommends both of these actions as well.

Store the battery in a cool place at about a 40% state-of-charge.

I had read Apple’s battery calibration routine back when my first battery was going bad. But it was too late to revive that battery. So when i got my second battery i figured that i would apply the concept of allowing it to drain fully, then recharge fully — every time. If a calibration is good for the battery, then why not just do that all the time?

What To Avoid

My MacBook Pro is a desktop replacement for me. That right there is a problem, because i’m not exactly using it as intended. Probably 95% of the time it’s plugged in to the wall, sitting on my desk at home or at work. 3% of the time it’s in transit, in sleep mode or powered off, in a bag. So i use it as a proper portable notebook on battery power only about 2% of the time. That “calibrate every time” theory i had wasn’t necessarily terrible, except that after those full charge cycles, the battery stayed in the system and the system stayed plugged in to the wall. The problems in this scenario are that the battery is being “stored” in the running computer (high temperature) while it’s plugged in (full capacity/constant charging). If Battery University, Apple, and my own experience are to be believed, then that’s pretty much the worst thing you can do to your battery.

Halfway through my second battery, i got a Rain Design mStand to elevate my MacBook Pro, which should help with air circulation and system temperatures.

How To Not Use The Battery

I simply remove the battery when i’m parked at my desk. You can hot-swap the battery while the MacBook Pro is running and plugged in to AC electricity (i can’t speak for other models and brands), so it’s not an issue to pop the battery back in when you need to move. Though, the one hazard in doing this is Apple’s otherwise genius MagSafe connector — it is far too insecure if you are not at a stable location. A cord disconnect results in an unsafe shutdown and you lose your work — only happened to me twice so far.

Another trick i’ve discovered is pulling power once the system is asleep (again, i have no idea if this works for any other notebook systems). You may have seen this if your MacBook battery drained completely — when power is restored, you get that faded white screen, and it takes a little longer to wake up. The memory is written to disk when going to sleep so if power is lost, it can be reloaded and resume as it was. If running off AC (without the battery), put it to sleep (wait for the pulsing white LED), then simply pull the cord; if running on battery, put it to sleep then remove the battery. This lets you transport/store the notebook without using the battery at all, and lets you resume where you left off (hit the power button to wake). The point of doing this is to keep the battery out of the system away from high temps and to stop battery discharge. Even in sleep mode, the battery is slowly trickling power to the system. Over longer sleep periods, this will extend your battery life, essentially like a complete shut down.

A lithium-ion battery provides 300-500 discharge/charge cycles.

It’s not clear if 300 cycles refers to a full drain and recharge. But both Battery University and Apple prescribe shorter, partial use as the norm. Avoiding battery use altogether with safe storage practices and instead opting for AC power extends how long those limited recharge cycles will last you. If you did one full recharge every day, the battery might be in bad shape after just one year. My original battery was unusable after 10 months. My second, with a conscious effort for regular calibrations, lasted about 18 months. My third is on track to maintain usable capacity for 3 years or more.

It pays to maintain the health of these batteries — they do not come cheap. If Apple (or the Genius handling your case) won’t replace your battery under warranty, it’ll cost you $129 for a fresh one. OWC usually offers a “Major Brand High Capacity Replacement Battery” for under $50 with a 90 day warranty. Can’t vouch for the product, but OWC is typically pretty legit.

The Short Version

• Don’t use your battery.
• Don’t leave your notebook plugged in with the battery installed.
• Use and charge your battery for short periods, avoid frequent full drain and charge cycles.
• Calibrate your battery as recommended by the manufacturer.
• Remove your battery when not needed.
• Keep battery temperature as low as possible.
• Shut down or use “powerless” sleep to minimize battery wear.
• Store battery at 40–50% charge in cold temperature.

Update on Battery #3

January 11, 2012: I realized i should post an update after reading a very similar new post on Lifehacker. My third MacBook Pro battery was installed May 2010 (20 months ago), and i have continued to remove it when leaving my system plugged in and to practice other “healthy” battery habits. I haven’t been super religious about taking it out or calibrating, but do so as often as i remember. coconutBattery reports that it’s currently at 80% maximum capacity after 20 months. The original battery hit 12% after only 10 months, and the second battery dropped to around 35% after 18 months, passing the 80% mark after about 12 months. So even accounting for variations in battery production, it seems pretty clearly conclusive that these tips i’ve outlined can have a dramatic effect on the life of your MacBook Pro battery. This can probably be applied to other devices as well, but my primary advice about removing the battery just isn’t going to work for many smaller gadgets and phones or newer MacBooks without user-replaceable batteries.