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The tales of a Macbook Pro’s battery

Ever had problems with the battery of your Macbook Pro? Thinking that you might have to replace it already when it’s been less than a year? Oh yeah, I know you know exactly what I’m talking about, yes, you! The MBP owner over there! Well you know what! I’ve had to go through those painful and frustrating moments too, but after a while of looking at the price of a new battery at the Apple store, I decided to give my mind a try.

Backstory

I’ve had my Macbook Pro for a while now. I dropped it many times and it ended up with a dent on the side right on the network port. What a joy I had when I was hammering my 3000 $ computer to put it back in shape. But, aside from a WiFi card replacement (which costed me 27.34$ on eBay), everything was working perfectly fine. What an indestructible, sturdy piece of art! Ironically, a few months later, my power adapter, which is supposed to be THE mythical MagSafe that no one can copy or break, decided to fail.

This is were our story starts

The little LED inside the MagSafe connected started to act up. It wouldn’t switch from green to orange when charging and later simply stopped turning on all together. Did I hammered too hard? Did I really broke the computer? Well, after nearly 8 months of enduring the broken adapter, I went to the conclusion that no, the computer was fine, but the adapter was dead.

On that day, I felt like cooking something so I picked up the laptop, place a movie on it and bring it with me in the kitchen. Surprise! By the time I was done getting everything out of the shelves, the computer simply shutdown. Hard stop. Blank screen. Nada. There was still a good 3 hours remaining in the battery so, what went wrong?

It took me two months to figure out the source of the problem and a solution that, luckily for me worked perfectly well. My battery have 97 cycles on the counter. It still holds 89% of its original charge so it can’t be that its time came. It made no sense. The next day, I went to buy a new battery but when I got to the Apple store, I saw that new power adapter with the L-shaped MagSafe connector. I wanted one anyway to replace the broken one so I picked it up and at that moment, I thought: “Hey! Maybe this is the solution!”. And it was…

I simply discharged my battery completely by rebooting the computer everytime it would crash to force every last bit of juice out of it, then, I charged it back with the new power adapter. Tada! Problem fixed! But… what was the problem in the first place?

Understanding Apple’s batteries

Laptop batteries costs a lot. Apple ones even more so. It’s not a “tax” as people like to believe. They are filled with complex electronics and this adds up to the cost. Its those same electronic components that caused problems. From my testing and experiences, I can say that the way the battery provide the power to the computer is extremely complex. The battery is composed of an undefined number of cell groups which each provide enough power to run the computer at a minimal state. Each of these groups have volt-meters and amp-meters on them. They are charged one by one to reduce cell degradation. If your battery is full, all groups are at their nominal volt and amp capacity. If your battery is half full, half of the groups are dead, the other half is full. It’s as simple as that. Were it gets more complicated is to how it is managing all of that power.

As I said, those groups can provide power for minimalistic usage. When you ask for more, like when you watch a movie, it uses more than one group at a time, but always in the same order. What happens if you charged that second cell group with a broken power adapter and filled it with a bad voltage? Exactly this. You would expect the electronics to skip the group and mark it as dead, but instead the voltages mix and the motherboard protect itself from a bad power input. By forcing a complete discharge the electronics thinks that those cells are empty so they will be charged the next time you plug the computer.

Voila! This is what happens when you provide bad power to your batteries. I’m lucky it worked. I could have blasted the battery if it was really badly damaged. The moral of this story is, don’t mess with your power; make sure it’s stable.