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Getting The Most Out Of Your Mac’s Battery – Part I [OS X Tips]

Getting The Most Out Of Your Mac’s Battery – Part I [OS X Tips]

The new iPad requires a lot more power than the iPad 2. How much more power? So much that despite an astounding 70% increase in the new iPad’s battery capacity (42.5 watt-hour up from 25 watt-hour), it will still run for the same amount of time as the iPad 2 on a single charge. The new iPad is a power-hungry beast and, therefore, knowing a thing or two about its battery is more important than ever.

If you’ve owned any type of portable device for an extended period of time you’ve probably noticed that its battery gets worse with time. You may have wondered what you could do to maximize your device’s battery life or even suspected that a short-lived battery was defective, but didn’t know what to do about it. Maybe you’re interested in extending the usage time you get out of a single charge or need even more battery power than your Mac’s internal battery has to offer, but don’t know what to look for in an external battery pack. This is a two-part guide on the battery basics everyone needs to know. It’s aim is to give you useful information about the batteries used by all of your Macs – including the new iPad.

Part I offers a little bit of background on lithium-ion batteries and covers the essentials of battery life and care. Part II provides you with the fundamentals of maximizing your Mac’s usage time through optimizing power saving settings or supplementing your existing battery with an external power source.

A Little Bit About Your Mac’s Battery

In these articles we’re talking about lithium-ion batteries (sometimes called Li-ion). If you follow the advice found here – or anywhere else – be sure to take a moment to confirm that the offered advice is tailored for the type of battery you are using. Following the wrong type of advice could be harmful to your battery or even dangerous.

There are two main types of lithium-ion batteries being used in Macs right now: standard lithium-ion and lithium polymer (sometimes called Li-poly). Most Macs currently use lithium-poly batteries, but some models use lithium-ion. The good news is that both lithium-ion and lithium-polymer don’t really differ in any way the average consumer needs to be concerned with. The behavior and requisite care for both types is the same and the advice provided here is applicable to both.

Unlike other commonly used battery types such as NiCd (nickel-cadmium batteries) or NiMH (nickel–metal hydride batteries), lithium-ion batteries have emerged as the favored battery for use in high-tech consumer electronics because lithium-ion batteries offer several advantages over other battery technologies. For example, lithium-ion batteries relatively low maintenance. They do not need to be primed nor do they suffer from “the memory effect,” which requires users to frequently discharge the battery in order to ensure proper battery function. Manufacturing lithium-ion batteries has become highly sophisticated and cost-effective and the development of Li-poly batteries, with their ability to be shaped and molded to virtually any size or form, has enabled product designers and manufacturers to explore new and ambitious product designs. For all of these reasons, lithium-ion batteries are the battery of choice for consumer electronics and will continue to be until newer battery technologies emerge.

Battery Life

Battery life refers to your battery’s ability to hold an acceptable amount of power after a given number of charge cycles or age. For obvious reasons, you want to maximize the number and quality of charge cycles during your Mac’s life. Most manufacturers specify that a lithium-ion battery’s life is approximately 300 to 500 charge cycles or five years – whichever comes first. This means that when a lithium-ion battery is nearing the end of its life its fully charged capacity will begin to dip below 70% of its original capacity.

One charge cycle is completed when a battery uses 100% of its charge capacity. But this does not necessarily mean that a battery needs to be discharged from 100% to 0% in one go. For example, one charge cycle is completed if a battery is discharged to 50% one day, recharged, and then discharged to 50% the next day.

If you’re on a Mac that uses OS X, you can easily check how many charge cycles your battery has undergone from the system overview. On Macs running OS X 10.6.x or later, Apple provides a basic battery health diagnostic tool, which you can access by holding down the Option key and clicking the battery status menu. This diagnostics tool diagnoses the condition of your battery as “Normal,” “Replace Soon,” “Replace Now,” or “Service Battery.” There are also applications that can provide this information as well as other useful information. I personally use iStat Pro (free) on my Macs and iStat for the iPhone (99 cents), but there are many options out there. Find one that works best for you.

Maximizing Your Battery’s Life: Battery Care When Your Mac is New

In order to maximize battery life, there are two things that you should do whenever you get your hands on a brand new Mac. First, set up a reminder to notify you of the important dates in your Mac’s life such as the expiration of its One-Year Limited Warranty or AppleCare. All Macs – whether purchased new, refurbished, or even used – are covered by Apple’s warranty and, if purchased, AppleCare or AppleCare+. You should set a reminder to tell you to check your Mac’s battery usage time (among other components) periodically, but at minimum once two-to-three weeks before the warranty or AppleCare expire. The key here is to catch battery problems while there’s still time to have them fixed by Apple under warranty or AppleCare because the service might be free.

Second, calibrate your Mac’s battery when it’s new and note initial usage time; write it down somewhere. Use this as a point of reference as your Mac ages. Calibrating a lithium-ion battery resets the internal circuitry it relies on for tracking its remaining charge. Over time, the accuracy of the battery’s internal gauge gets out-of-sync with the battery’s actual capacity and recalibration is necessary in order to properly track your battery’s charge.

Apple recommends that you calibrate your Mac’s battery when it’s new and then once every few months thereafter. Calibration is very easy and may be accomplished by following these steps:

  • Step 1: Charge to full capacity.
  • Step 2: use battery in fully charged state.
  • Step 3: disconnect from power adapter and continue use.
  • Step 4: continue use until Mac shuts itself off.
  • Step 5: let Mac sit for ~30 minutes to an hour (some say longer).
  • Step 6: recharge again to full capacity. The charge should be uninterrupted.

If you require additional assistance with calibration Apple has its own site on battery calibration and there are numerous step-by-step guides out there too. Just Google the terms “Mac lithium-ion battery calibration.”

The reason for re-calibration has nothing to do with cyclic memory (“the memory effect”) that affects NiCd or NiMH batteries. In fact, regularly draining your Mac’s lithium-ion battery to ~0% – conducting “deep discharges” – is a very bad idea because it will strain your lithium-ion battery.

Maximizing Your Battery’s Life: Battery Care During Your Mac’s Life

It’s easy to properly care for your Mac’s battery provided you follow a few simple rules. First, recalibrate your Mac’s battery once every one to two months. Simply follow the battery calibration steps described earlier in this article. Set a repeating alarm in iCal to go off at the end of every month. Recalibrating your Mac’s battery is so important that Apple even offers pre-made iCal reminders on its battery care page.

Second, exercise your battery regularly. Don’t let your Mac’s battery sit around full, or empty. It’s a bad idea to keep your device plugged in 24/7 because when plugged in your battery will remain in a fully charged state. When fully charged, a lithium-ion battery is exposed to higher than ideal voltages levels, which stress the battery. If your battery is put under stress it will age more quickly than it otherwise would. Likewise, regular deep discharges also stresses lithium-ion batteries and may reduce the life of the battery or even lead to battery failure. By design your lithium-ion battery should be used regularly and using it regularly will maximize its life.

Third, keep your battery away from extreme temperatures. Your Mac’s battery will function the best at approximately room temperature (68°F). Exposure to extremely hot or cold temperatures will causes significant stress to your battery and will shorten your battery’s life. Don’t leave your Mac in a car on a hot summer day or cold winter night. Likewise, take steps to ensure that your Mac isn’t exposed to high temperatures during periods of charging or heavy use. While it’s normal for lithium-ion batteries to get warm under these circumstances, you should avoid letting it get hotter than 95°F for any extended period of time.

Fourth, when storing your battery, store it properly. A stored battery will inevitably continue age, but you can dramatically minimize the effects of aging by following two simple rules. Store the battery at approximately 40% capacity in a cool (59°F or less) and dry place. The 40% charge level will ensure that age-related capacity loss is minimized while keeping the battery in operating condition and allowing for self-discharge, which is approximately 5% within the first 24 hours after a full charge and 1%-2% each month after that. The cool temperature (but not too cold) will also further slow the battery’s aging. Remove the battery from your Mac or, in the alternative, shut your Mac down completely. If your Mac is merely in sleep mode it will continue to draw a small amount of power and, therefore, it may completely drain its battery, which should be avoided.

What To Do With A Dead Battery

When your battery no longer holds an adequate charge, you may need to have it replaced. If possible, you should seek to have it repaired under warranty or AppleCare, but even if your Mac is still covered by one of these programs you may still be out of luck.

Apple’s One-Year Limited Warranty and AppleCare do cover batteries, but the programs handle them as a special case because batteries are classified as “consumable items.” Like the tires on a car, they wear out and poor care of abusive usage practices may cause them to wear out faster than expected. Apple’s warranty and AppleCare do not cover batteries that have worn. Apple will typically only replace batteries when they are indisputably defective. If your battery isn’t defective, you must have it replaced pursuant to Apple’s Battery Replacement Program or replace it yourself. If you think your Mac’s battery may be defective, consider the following tips.

First, perform your own diagnosis. Check your battery’s age and condition and re-calibrate the battery. After re-calibration run your Mac as you normally do, take note of the battery life it gets on this charge, and compare that against the amount of battery life you got when your Mac was new. Apple is going to do its own diagnostics, so save yourself a trip to your local Apple Store. You may find that re-calibration fixes your problems or that, although your battery may be nearing the end of its life (i.e. you’re still getting 75% charge capacity after 350 charge cycles), it still hasn’t deteriorated to such a point where Apple deem it defective and replace it.

Second, have you mistreated your battery? Have you kept your battery active? Did you frequently leave it in a hot or freezing car? Did you leave your battery in a fully charged or uncharged state for days or weeks on end? If the answer to any of these questions is yes, then further diagnostics may reveal that you’re not eligible for a replacement because you had exposed the battery to harmful conditions. Although Apple will rarely refuse to replace a battery on these grounds, you shouldn’t try to get a battery replaced if you know you’re at fault for damaging it. If the answer is no, then having thought about how you cared for your Mac’s battery before you’re interrogated by a Genius may help your argument; it shows that you know a little bit about proper battery care. This may help to assuage any doubts a Genius may have about whether a free replacement is in order. Let’s face it; complete ignorance on this topic isn’t going to help you.

Fourth, is your Mac’s battery physically exhibiting signs of defect? Even if our Mac is outside of its warranty period, there’s a strong possibility that Apple will still replace the your battery for extreme defects – free of charge. Common signs of extreme defects include battery swelling, sparking, or extreme temperatures during charging or use. If your notice your battery to be swelling or is generating excess heat you should immediately stop using it and contact Apple. Defective batteries can be extremely dangerous and Apple would rather give you a replacement than your defective battery harm person or property. If any Apple representative refuses to replace such a defective battery you should seek to speak with a manager before giving up.

Replacing Your Mac’s Battery Yourself: The Basics

If you’re exceedingly tech-savvy or just feeling adventurous you can save money by replacing your Mac’s battery on your own. Obviously, if your Mac is still covered by its warranty or AppleCare you should pursue those options first as repairing or replacing the battery on your own may void any existing warranty.

Although, by design, Apple has made it extremely difficult for users to access their own batteries it’s still possible to do it yourself. In order to replace your Mac’s battery you need a replacement battery, the right tools, and a little bit of know-how. Don’t try this at home unless you understand what you may be getting yourself into.

If you succeed in replacing your Mac’s battery, be sure to dispose of it properly. Apple offers free battery recycling provided you bring the battery to any Apple Store location. Disposing of batteries improperly is dangerous and harmful to the environment and is illegal in many jurisdictions. If you are unable to take your old battery to a nearby Apple Store you should do a little research to learn how your town handles battery disposal.


About the author

Jonathan ZschauJonathan was introduced to Apple at the age of five when his family bought its first computer, an Apple IIGS, in 1986. He has owned and used Macs almost exclusively ever since. He is an attorney from Boston, Massachusetts where he focuses on litigation technology. As a contributor he writes about consumer protection issues related to Apple products. He is also the author of Buying and Owning a Mac: Secrets Apple Doesn't Want You to Know.

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