Mac Battery Maintenance

How to maintain your MacBook or MacBook Pro’s battery life

I have been asked many times how to get the best out of a laptop battery. So here is a break down of the best maintenance options for your machine.

Because a Macs battery capacity can vary so drastically depending on how the machine is used on a regular basis, there is no easy way of establishing if a battery is holding charge for the correct amount of time, or if the battery has degraded and is at a point where it should be replaced. But there are methods of maintaining the battery so the cells do not die as quickly, which will increase the length of time the battery will hold a higher charge before it needs to be replaced.

The functions of the battery are reliant on a few different factors, one being the calibration of the power management unit of the machine (referred to as the SMC, or systems management controller in the intel generations such as the MacBook and MacBook Pro ranges), which is usually a function of the main logic board.

In short, the best way of using your machine is to charge the battery to 100%, then remove the mains plug and run it from the battery until it goes to sleep. This caused the battery to fully cycle, giving it a chance to replace each battery cell, which prevents them from dying off. If this is not done, it will reduce the Full Charge Capacity, meaning the overall battery capacity will begin to drop with time. If you do not have the ability to have it cycled continuously, then at least 2-3 times a month would still help the battery life in the long run.


Calibration Issues
In order to get a good reading from your battery, it is first important to recalibrate the SMC so that the battery is registering the correct capacity to the machine. if the calibration is off slightly, your machine may be showing that it has 80% left of its life, but it may drop 20-40% suddenly, occasionally putting the machine in standby mode unexpectedly, or worse, powering down the machine causing you to lose your work. This is usually caused by a calibration issue, either by the battery having a really low charge capacity, or by the SMC calibration being off, as mentioned earlier.
There are a few resets that can be done to re-calibrate the battery.
 The first thing to do is to reset the backup PRAM Battery. To do this, shut the machine down, hold down the following 4 keys, Apple, Alt, P, R, then press and release the power button. Keep holding the 4 keys until you hear the machine chime a second time, then you can release the keys and let it boot fully. This has reset the PRAM battery.

Then reset the Power Management Unit, or SMC (Depending on what range of machine you have)

PMU Reset (Power Management Unit)

This reset is for PPC machines (pre-intel) and Intel machines with removable batteries (such as the early MacBooks and MacBook Pros)

(please note, some PPC machines have PMU Reset buttons on the main logic board. Ranges such as the Titanium PowerBook G4. the below method is not required for these models. you can simply press this button for 10 seconds to complete the reset)

  • Ensure the Mac is powered down
  • Remove the external power source and remove the battery
  • hold the power button down for 10 seconds
  • refit the battery and mains cable

The process is complete

SMC Reset (Systems Management Controller) For Intel Machines

  • Ensure the Mac is powered down
  • Plug in the MagSafe power adapter to a power source, connect it to the mac if its not already connected
  • On the built-in keyboard, press the (left side) Shift, Control, Option key (the option key is also known as the Apple key) and the power button at the same time
  • release all the keys and the power button at the same time
  • press the power button to turn the computer on

The process is complete

(please note: you will probably not notice the reset actually happening during this stage. The only external identifier is the that LED on the MagSafe power adapter may change states or temporarily turn off when you reset the SMC)

Checking your Battery Capacity

As mentioned earlier, it is very difficult to know exactly how long your battery should be able to last. Not only does each process have different power requirements, but with age, batteries naturally degrade and lose capacity as the cells begin to die off.
The easiest way of taking a reading from the battery is based off the System Profiler registering both the ‘Full Charge Capacity’ and the ‘Cycle Count’.

The full charge capacity is the batteries current maximum capacity in Milliamps Per Hour, and the cycle count is the amount of times is has been fully cycled. (a single cycle is when the battery is charged from 0-100%, then drained down until the machine goes to sleep)

To get a reading of these details, click on the Apple in the top left of your screen and select ‘About This mac’. A new window will open on your screen. Then select ‘More Info…’ On 10.6 and earlier, this will have then opened the ‘System profiler. You can then click on the ‘Power’ tab on the left side, and take a reading of the ‘Full Charge Capacity’ and ‘Cycle Count’. On 10.7 and 10.8, you then need to click on the ‘System Report’ button to open up the detailed panel. (from which you can select the ‘Power’ tab and take a reading)

Annoyingly, in 10.7 and 10.8, they have stopped referring to it as the ‘System Profiler’. it is now called the ‘System Information’. If you need a quick method of finding this page, open up a spotlight search or a finder window and type in ‘System Profiler’ or ‘System Information’, depending on your OS version. (for those of you that like to know exact locations, it is in the Applications folder under Utilities)

If you would like to see what capacity your battery should have had when it was new so you can see what percentage of your battery capacity is left, go to the listing on our website and read the full description of the relevant battery range. Our batteries are graded both cosmetically and by their remaining ‘Full Charge Capacity’. A-Grade holds between 90-100% of its original change, B-Grade is between 75-90% and C-Grade is between 50-75%.

If you are unsure of what capacity your battery should have and our listing doesn’t state it clearly enough, drop us a line and we can let you know.

Please also note: As a new feature of 10.6 (and later), Apple have added a function where it will come up with a ‘Replace Battery Soon’ message under the power tab to the right of your menu bar. This is a basic software function, by which the ‘Full Charge Capacity’ is looked at. If the battery is below 90%, it will come up with this message. Also, if the calibration is slightly off and it thinks it is lower than it really is, this message will also come up. Doing the SMC or PMU reset mentioned above can sometimes rectify this. Otherwise, if your battery is lasting fine and has a decent ‘Full Charge Capacity’, don’t let this message alarm you into replacing it unless you have some other reason to be concerned.
Later models of MacBook Pros have internal batteries, which are not designed to be consumer replaceable. These are more difficult to check to see if they are swelling, but a visual inspection of the earlier ranges can also let you know if the cells are dangerously expanding within the casing. If this is the case, ensure you remove it from the power source and dispose of it correctly as soon as possible, as batteries can explode if they swell too much


About nojboy715

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