Alright, so lets talk about cycles as there seems to be some confusion over my last video.
Not all computers and batteries are equal.
First let me show you the official cycle life of different batteries right from Apple.
The iBook G3 and G4 systems had a cycle life of around 300
The Powerbook systems also had a cycle life of around 300
The original MacBook series had a cycle life of around 300
The MacBook Pro from the same era also had around 300
Once you hit the 2009 MacBooks things start to change and you get 1,000 cycles
Same with the newer MacBook Pro's and the MacBook Airs
Lets also discuss what a cycle is.
A full cycle is when you dischage the battery all of the way down, and then all of the way
back up.
But what if, for example, you discharge the battery half way and then charge it back up?
This is only half of a cycle.
So you'd have to do this twice before it would equal a full cycle.
OK so lets put that in perspective.
Um, Just because Apple throws out a number like 300 cycles, doesn't mean the battery
won't work past 300.
It just means that after 300 cycles, the capacity will begin to degrade.
So at maybe 400 cycles the battery may only last 2 hours instead of 4 hours, and you know
when you get to 500 cycles it may only last an hour and when you get to 6 or 700 cycles
it may only half an hour or it may not work at all.
Lets talk about what factors besides cycles affect a batteries life.
Temperature is a big one.
Leaving it in hot environments, especially while in use, will degrade the battery much
faster.
Once you get around 120 degrees, like inside of a hot car or something, you can pretty
much kiss your battery goodbye if it spends much time there.
Charging state matters.
For example, if you were to let the battery completely discharge and then sit it on a
shelf for a year like that, well you can pretty much kiss your battery goodbye because its
going to be dead.
If you are going to store the battery, take it out of the laptop so that it won't discharge
as quickly and try to charge it up periodically.
If the battery is internal and the computer is going to be stored for a while, then just
periodically make sure to charge the thing up.
Depth of cycles.
It is usually much easier on the battery if you only cycle the battery a little bit, then
charge it back up, rather than always cycling it completely.
And another thing is age.
As the battery gets older it will always degrade some even if you haven't used it.
Ok, so now that we've covered the life cycle of a battery, now lets talk about calibration.
If you open up a battery you'll find a tiny computer, or microcontroller inside.
This controller is what keeps track of how many cycles the battery has gone through,
as well as other information about the battery.
Two of the things this controller attempts to track is how much capacity is left in the
battery and what the current state of charge is.
Just so we're clear on this, the capacity is the amount of power the battery can actually
store in its present condition, which As we've discussed, that shrinks over time as the battery
degrades.
The state of charge is different.
That's a percentage of how full the battery actually is.
Let me give you this example.
Imagine comparing it to a tank of liquid.
The capacity would be the size of the tank.
The state of charge is like how full the tank is.
But it doesn't always get it right.
The controller really doesn't know exactly how much power the battery can store.
The only things it can really monitor is the voltage and the current as power is taken
from or put back into the battery.
It uses the history to track what it believes is the state of charge and the capacity.
And this is how its possible for a battery to become miscalibrated.
Essentially what this will cause is the battery gauge up here on the screen will not be an
accurate reflection of the real battery.
Keep in mind, this information is is just an estimate.
Ok, So how can you be sure your battery is properly calibrated?
Well, here's the best way to do it.
First of all, charge the battery all the way up overnight.
Then, go into the system preferences under power and edit the parameters so that the
computer will never shut off the screen or go to sleep.
Now, set a timer and unplug the computer.
Make a note of how long the computer thinks the battery will last.
Be sure to keep an eye on the computer.
Ignore any warning messages you get about being low on power.
Wait for it to completely shut off.
Then, make note of the time of how long the battery was able to run.
Then you can compare it to what the computer had estimated.
Then charge the battery all the way back up immediately.
Your battery should now be calibrated and the estimate should be more accurate.
Well, I hope you enjoyed the video.
I've got one bonus link I want to put up on the screem here for you.
This takes you to an official apple document that lists all of the cycle lifes for the
different computers they've had over the last 10 or 15 years.
So if you're not sure what the cycle life is on yours, go to this website and you can
find out exactly.
otherwise, tell me what you'd like to see in the next video.
And if you'd like to take part in a future video, send me an email and we'll see what
we can do!