20Sep 2014

Damage in a battery happens. You can’t stop it. It’s part of the physics. Yes, it is possible to mitigate it. It is possible to postpone its onset. It is possible to reduce its impact (that’s part of what our company Qnovo does)… But it’s always there and we need to deal with it. Battery manufacturers have tended to sweep this issue under the rug but it is now coming back to bite them hard.

In technical terms, this damage inside the battery is referred to in terms of “cycle life.” It is essentially a measure of how many times the battery can be charged and discharged before it is deemed dead. As I mentioned in the previous post, a battery is deemed dead when its maximum capacity reaches 80% of its original capacity as a fresh battery. So say a fresh battery has a maximum capacity of 2,500 mAh on its first day of use. After some number of charges and discharges, the internal damage reduces this maximum capacity. Eventually, this figure reaches 80% x 2,500 mAh = 2,000 mAh at which point it is officially deemed to be “dead”, i.e., it needs to be replaced.

Why 80%? and not 75% or 63.1849%? Because experience has shown that shortly past the 80%-mark, the damage accelerates rapidly and the battery capacity plummets very quickly. Not good!

But now you are saying, “how can I know?” Well, welcome to the world of opacity in how battery makers specify their products. As a consumer, you don’t know, nor you can measure it easily. Device makers tell you trust me, but you should not! All these apps that you can download from the Apple or Google stores also don’t tell you anything. Right now, sadly, the only way you can tell that your battery is dead or dying is because it feels that it is dying. Your battery can’t last you the day when only a few months earlier it did. Now to be sure, you also have to make sure that you don’t have one or more rogue apps draining the battery in the background. So if you reset or even restore your mobile device and its battery is still not delivering, then it is a fairly strong hint that something is very wrong with the battery. If you are asking “why can’t you fix it,” the answer is “we can and we are.” Let your mobile device manufacturer know that you are not happy if you suspect your battery cycle life is compromised.

Let’s get back to cycle life. As you can see, cycle life and battery capacity are very closely tied together. Capacity is effectively the capacity that you get on your first day of operation, and cycle life is a measure of longevity of your battery’s capacity. Cycle life is almost like the “Expiration Date” printed on a gallon of milk at the grocery store; except imagine that grocery stores decided one day to simply eliminate printing this crucial date. Grocery stores don’t dare do it! Well, many mobile device manufacturers choose to hide or not disclose the cycle life — effectively this expiration date of the battery is hidden. We are working on changing this behavior. But for now, I will give you some hints and tips on how to deal with this.

Most mobile devices including smartphones and tablets are rated to 500 cycles, i.e., you, the consumer, can expect to have 500 consecutive full charges and full discharges before your battery is deemed dead. Some devices do better than others. For example, older Apple iPhones lasted more than 500 cycles, whereas others either made 500 or fell shy of that figure. 

But some carriers (or operators are they are called outside the US), and in particular, Verizon Wireless, began demanding that mobile device manufacturers increase their cycle life specifications to 800 or more cycles, to effectively cover a 2-year warranty on the device. This new specification is beginning to proliferate but battery manufacturers are not happy! Increasing cycle life performance is not easy for them, and guess what, most of them are based in Asia and they don’t like to ask for help!

So one of the tricks that manufacturers do to increase cycle life is to — hold on to your seat — increase charge times! Ouch! Now, you are becoming increasing familiar with the battery whack-a-mole strategy that battery manufacturers follow. You want more capacity, well, you may get worse cycle life…you want better cycle life, well, you will get worse charge times….and so on.

Fortunately, the technology to fix this whack-a-mole problem already exists…mobile device manufacturers have to deploy it more universally. For now, here are some hints — albeit a little inconvenient — that you can apply to extend the cycle life of your life battery:

  • Charge your device slowly using the USB port on your PC or notebook, not wall charger or AC adapter. This effectively limits the charging current to 500 mA. Yes, it is slow, but if you are not in a rush, it will help your battery.
  • Charge at room temperature! Not on your car dashboard in the middle of a hot sunny day, or worse yet, in the middle of a cold winter. Batteries hate being charged at temperature extremes, especially below 60 °F (or 15 °C), and above 95 °F (or 35 °C).
  • If you are not traveling or need your phone fully charged all day, then charge your battery to about 80 or 85% — not to 100%. This will also help being gentle on the battery. 

More later.