19Sep 2014

Yes, I did. That’s when you wake up a few months after you make a proud investment in a new mobile device, then you realize that the battery is not lasting as long as you wanted.

Well, first to be safe, you have to make sure that you don’t have too many apps running in the background draining the battery without your knowledge or your permission. But assuming that you already reset your phone, deleted the useless applications, and turned off all the background app refreshing, and you are still not getting the battery life that you had only a few weeks or months ago, then you are right, you are now experiencing the signs of battery damage, or in geek terms, it’s called “capacity fade.”

Remember when we talked earlier about the charge capacity of a battery and said it is measured in units of mAh. So let’s say that you battery is rated at 2,500 mAh. So when your device is fully charged, and your fuel gauge in the upper right hand corner of your screen is reading 100%, it means that your battery is holding about 2,500 mAh of electrical charge…using the earlier analogy of the water bucket, it means the bucket is full and is holding some number of gallons of water.

But this assumes that the battery is new. As damage sets in the battery, its maximum capacity will actually degrade over time and use. This can happen for many reasons, such as poor manufacturing, extended exposure to low or high temperatures…etc. (we will get back to this at a later time). So the battery you have now has a maximum capacity of say 2,200 mAh instead of 2,500 mAh. In other words, you will notice a decrease in your battery life by about 1 to 2 hours per day.  

So now you are frowning, and possibly complaining: “But, but, but….the fuel gauge is still reading 100% when it is full.” Yes, the fuel gauge only reads the available charge in the battery as a fraction of the maximum available capacity in the battery (it’s a mouthful). In other words, on day one, your battery was able of holding 2,500 mAh, so 100% of the fuel gauge is then equal to 2,500 mAh. But after 6 months of use, the battery can only hold 2,200 mAh, and the 100% displayed by the fuel gauge is now equal to only 2,200 mAh. Ouch! 

If you are thinking about where you can read the lower battery capacity of 2,200 mAh, the answer is nowhere. You can’t. The smartphone manufacturer and battery vendors either can’t tell you or don’t want to tell you. This is called “state of health” of the battery. 

When the battery capacity drops to 80% of its original capacity — in our example here, it is 80% x 2,500 mAh = 2,000 mAh — the battery is deemed dead and must be replaced. But as you gathered, it has been difficult if not nearly impossible for customers and consumers to prove that they have a dead battery.