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


Part II of this two-article series focuses on battery usage. Battery usage refers to how long you can use your Mac off of a single charge cycle. In addition to proper battery care, there are numerous ways to improve or supplement battery usage. When there’s no power outlet available, consider the following two options. First, optimize your Mac for maximum battery life. Second, supplement your Mac’s battery with a secondary power source.

Optimizing Your Mac’s Settings.

Apple has informational pages suggesting how best to optimize a Mac’s settings for maximizing battery usage. It’s a good idea that you start with the power saving suggestions officially sanctioned by Apple because many of the more advanced tips and tweaks – although mostly harmless – widely vary in their sophistication and applicability to various different makes and models of Macs.

For the basics, check out these links:

Each of these pages has a sub-section titled “Optimal Setting” or “Optimize Your Settings,” which detail Apple’s tips for improving battery usage time. Some suggestions may seem obvious (i.e. turn down your screen brightness), but there may be one or two you haven’t thought about.

There are also many more device-specific guides, which may offer more custom-tailored advice for your Mac. Some advanced tips that reportedly help to improve battery life include disabling Flash in your web browser, activating automatic graphics switching on certain MacBook models, turning off keyboard backlighting, switching off 3G functionality or other network settings).

Not all advice is necessarily going to be helpful or correct, so be sure to do your research before trying anything too drastic (i.e. completely draining battery to remedy “memory” issues, disabling a CPU core, etc.). Limiting your search to reputable websites or Apple’s own technical support forums will help to ensure that the information you find is correct. Make sure to confirm that the tip is applicable to your specific Mac and that multiple sources have reported it to work. Here are four tried and true suggestions, which should immediately improve your Mac’s battery usage time.

Manage Your Applications

Keep track of what applications you have running on your Mac and quit applications when not in use. Running applications in the background – especially processor or graphics intensive ones – will drain your battery extremely quickly.

If you’re on a Mac running OS X open up Activity Monitor, which is located at \Applications\Utilities\Activity Monitor. Activity Monitor features a list that will show you all of the active processes on your Mac. Sort the list by “% CPU” to get a sense for processes that may be eating up your battery. To quit a process select that process and click on the “Quit Process” button in the upper left corner of Activity Monitor. You may be surprised at some of the programs running in the background. Be warned that quitting integral system processes may cause system instability and may prompt a system restart. If you’re unsure about what to quit, try first restarting your Mac, which may help to clear out rogue processes without the need to force quit individual ones.

Activity Monitor isn’t currently built into iOS devices, but you can achieve a similar result with apps like Activity Monitor Touch. To isolate potentially power-draining applications, use Activity Monitor Touch to get a sense for what is running on your device. Quitting a specific app can be accomplished from the Recently Used Apps list. To open the list, press the home button twice. A list of icons will appear at the bottom of your iOS device’s screen, which displays your recently used apps. Removing apps from this list will have the effect of quitting it if it is still running. Press and hold any app icon displayed within the list; it will start to wiggle and a red minus will appear in each icon’s upper left corner. Tap the red minus to remove the app from the list and quit it. Keeping an eye on this list and closing out extraneous applications will help conserve battery usage.

Dim Your Screen

Dim your Mac’s screen to 50% or less and set screen dimming to occur automatically in your Mac’s OS X or iOS power saving preferences. Dimming your Mac’s screen is widely considered to be one of the simplest and most effective tactics for improving battery usage. In my research I came across some articles and forum posts suggesting that users invert their Mac’s screen in order to save power. Although inverting your Mac’s screen may help relieve eyestrain, it will not significantly impact your battery life, as the primary power drain isn’t tied to the orientation (the color) of the pixels themselves, but the LCD screen’s backlight. Unless Apple starts using newer technologies like OLED screens in its devices, which generate light on a per-pixel basis, screen inversion will likely continue to have negligible impact on battery life.

If you’re curious, screen inversion may be accomplished with the keystroke Control+Option+Command+8 on a Mac running OS X and by sliding the White on Black option to ON at /Settings/General/Accessibility/White on Black on iOS devices.

Turn Off Peripheral Components And Activities

Turn off Wi-Fi, Bluetooth, and other unused hardware systems such as external hard drives. Remove any discs from your Optical Drive. Macs running OS X have some options under the Energy Saver section of System Preferences such as putting the hard drive to sleep when possible. Adjust software settings to minimize background activities. Turn off or decrease the frequency of auto-save, auto-check, and Push notifications. Disable Spotlight indexing if you don’t rely on it. Every little bit counts and turning off unnecessary components will improve your battery usage because the harder your Mac has to work the more power it will use.

Keep Your Mac Cool

Not only will keeping your Mac cool improve your battery’s overall life expectancy but it will also help it get the most out of every charge. If your Mac gets too hot, it will have to work harder to keep itself cool. Many Macs have a number of built-in mechanisms such as cooling fans, which it activates when it needs to cool itself. Using these fans requires power and the more power your Mac uses the faster its battery will drain.

Be mindful of where you put your Mac when you use it. Placing your Mac on soft surfaces such as a pillow, blanket, carpet, or uneven surfaces may trap heat or block important air vents. This will cause your Mac to heat up more rapidly. You should avoid placing your Mac against surfaces that would otherwise obstruct natural airflow around it. For example, placing your Mac on an uneven surface or using a MacBook that’s missing several of its feet will not allow air to flow freely beneath it and, therefore, your Mac will lose some of its innate (through designed shape) ability to dissipate the heat it generates. Placing rulers or other small objects beneath your MacBook may help improve the airflow, which will help to keep your Mac cool.


Supplementing Your Mac’s Battery

Sometimes proper battery care and even the most efficient device usage just isn’t enough to get by. If, after trying all of the abovementioned tips you still need to extend your Mac’s usage time, then you should consider supplementing your Mac’s existing battery with an external power source.

Over the years Apple has made it more and more difficult to swap batteries out of its devices and, therefore, getting extra power isn’t as simple as carrying a spare battery. Your best solution is to get an auxiliary battery pack. There are dozens of options out there and choosing one that best suits you is a very subjective enterprise. When shopping around for, and using, an external battery pack there are several tips you should consider.

Battery Capacity

Pay attention to battery capacity. How much extra power do you actually need? Are you looking for a charger that’s going to pack enough juice to survive a backpacking trip through the Appalachian Trail or do you only need something to get you through a long flight?

Battery capacity is frequently rated in terms of amperes – usually milliamp-hours (mAh) for battery packs used on many Macs – which are units for measuring electric power (electric current) over time. For example, a 3.7-volt lithium-ion battery rated at 1,000 mAh will be able to power a device that draws 100 milliamps for ten hours, or a device that draws 200 milliamps for five hours.

When comparing batteries of the same voltage, the higher the mAh the longer the battery will last. Because not all batteries are the same voltage relying solely on a battery’s mAh rating can lead to some confusion. Therefore, when you are shopping for external batteries for your Mac you should be sure to pay attention to more than just the mAh rating. Knowing a little bit about measuring electricity may help you here.

Amperes, voltage, and wattage can be confusing concepts to wrap one’s head around and I found the following often-used analogy to be helpful. Picture your Mac’s battery as a tank of water with a garden hose attached to it. Electrical energy is the water pouring out of the hose. The water pressure or, the speed the water flows, is the voltage. The amperes are the diameter of the hose. Wattage is the actual numbers of gallons that ultimately pour out of the tank. You can see the relationship between the three by considering that you can get more water out of the tank by either using a bigger hose (more amperes) or higher pressure/speed (higher voltage) but the total capacity of the battery (wattage) is the same whether you have higher voltage and fewer amperes, or vice versa. What you’re interested in – the total power the battery has to offer – is the wattage or watt-hour rating. The more watt-hours, the more power that battery has in it.

The most useful measure of how much power a battery has is to measure the battery’s power in terms of watt-hours, which is the product of the battery’s voltage and its ampere rating. Apple actually represents its own batteries in terms of watt-hours. The mAh rating can be converted to watt-hours if the voltage of the battery is known. For example, let’s say that Battery A is a 3.7-volt lithium-ion battery and Battery B is a 4.2-volt battery. Multiply the voltage of each times their mAh rating to get watt-hour rating.

Battery A: 3.7-volts * 1,100 mAh = 4,070 mA-volt-hours, or 4.07 watt-hours.

Battery B: 4.2-volts * 1,000 mAh = 4,200 mA-volt-hours, or 4.2 watt-hours.

Although Battery A has a slightly higher mAh rating, Battery B actually has a higher watt-hour rating and, therefore, more power.  The difference here may seem negligible, but when comparing larger batteries or batteries of different brands or types the difference may prove to be significant.

Here’s a real-world example to help show where confusion might develop. Take the following two power packs, which come from the same manufacturer:

Power Pack A

Power Pack B

Power Pack A is 5-volts and is rated at 2,000 mAh. Power Pack B is a 28-amp hour battery, which translates to 28,000 mAh. That’s fourteen times more mAh than Power Pack A. But Power Pack B is a 12-volt battery, not a 5-volt battery. The effect of the voltage difference between the two batteries is clearer when you look to watt-hours instead of mAh. Converted to watt-hours Power Pack A has 10 watt-hours and Power Pack B has 336 watt-hours, which is approximately 33 times – not merely fourteen times – the power capacity of Power Pack A. The takeaway is that you need to look at more than just the mAh when comparing batteries.

Battery Size And Weight

Look at the battery’s size and weight. While total capacity is important, you will probably also want to consider the weight and size of a battery pack. As battery manufacturing technologies do vary, larger and heavier batteries are not necessarily going to give you more watt-hours per cycle. Although this may be less important when seeking power packs for larger Mac devices such as a MacBook, a few tenths of an ounce makes all the difference when we’re talking about an iPhone battery case. Moreover, battery packs come in all shapes and sizes and you may find that one that fits to your particular needs better than another. The best way to find one that’s the right size and shape for you is to test them out yourself. Stop by your local Apple Store or other electronics retailer and have a look at the batteries they have there.

Read The Reviews

Read the reviews. There are several leading battery pack manufacturers out there right now. Some battery pack manufacturers worth noting include HyperJuice, QuickerTek, and MikeGyver for Mac computers and mophie, Boostcase, and PhoneSuite for iOS devices. Check Newegg, Amazon, or other retail websites to get a sense of what people are saying about the battery packs that are out there.

Use The External Battery First

Finally, if you find yourself in a situation where you know you’re going to need the extra power, be sure to exhaust the external battery before resorting you your Mac’s internal battery. This will ultimately give you more usage time because exhausting your Mac’s internal battery and then recharging it isn’t as efficient because some power will inevitably be lost during the charging process. A number of battery packs do this by default, but it’s a good idea to make sure that this is how your external battery is configured to operate.

  • louiscutmore

    great articles jonathan…