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Battery Life Tips: Nursing your battery through a two year contract

With more smartphones coming with built-in batteries, learning how to properly care for your battery is important. You would like your phone’s battery to last throughout your two year contract. A degraded battery may force you to make a fairly expensive visit to a service center or attach an external battery pack. For some devices, neither option is available.

Fortunately, today’s batteries are easy to care for. But their performance can be seriously degraded by relying on old notions.

Will my battery last for two years? If you are the typical user, and you acquire a well built smartphone, the answer is yes. By a typical user, I mean someone who has mobile data enabled and uses a smartphone for two to three hours per day doing various tasks.

The typical modern lithium-ion and lithium-ion polymer battery you find in a mobile device should last for 500 charge and discharge cycles depending. Five hundred cycles should be enough to get you through two years. But let us get back to this later.

While manufacturers have favored built-in batteries as of late, a lot of focus has been placed on improving battery life. This has been achieved through the use of more power efficient components, often coupled with larger batteries. GSM Arena’s battery life tests on the Apple iPhone 5 rates it a 51 hours endurance “if you do an hour each of calling, web browsing and watching videos” each day. This is 13% higher than the 45 hour endurance rating for the iPhone 4S. Similarly, the HTC One was given an endurance rating of 48 hours, which is 30% higher than the 37 hour endurance rating of the previous HTC flagship, the One X.

When translating these 48 to 51 hour endurance ratings in the real world, you should expect to get half of this. Network signal strength and ambient temperatures can increase battery drain. Still, today’s modern smartphone should get past the workday with 20% to 30% of remaining battery life. This, plus batteries that are designed to survive 500 cycles, should be enough to get the typical user through two years of use.

Five hundred cycles is more than it sounds. When we talk about a battery cycle, it means a full charge and discharge. So if you charge your battery before it is empty, it will not count as a full cycle. For example if you charge the battery on your smartphone when it drained down to 30%, and then charge it a second time when it hits 60%, and a third time when it drained down to 50%, these three charges counts as only two cycles.

1ChargeCycleImage credit: Apple

Basically, if you usually charge battery when it gets to 30%, it should be good for over 700 charges.

The battery does naturally degrade over time. While the battery is designed to last 500 cycles, it does not mean that the battery will maintain a 100% charge throughout the 500 cycles. It also does not mean that after 500 cycles, the battery will die. After 500 charge and discharge cycles, your battery would be at about 70% of its original battery life. Your phone will still report that it is 100% fully charged, but it will really be at about only 70%. Basically, your battery deteriorates about 30%, gradually, over the 500 charge and discharge cycles.

Given all this, how do we make sure that we care for our batteries well enough so that they still maintain a 70% charge after two years of use? Here are some tips.

1. Avoid letting your battery drain below 20-30%. Partial discharges are actually better for your battery. The old rule that you had to fully discharge your battery, before recharging, applies to old Nickel-Cadmium batteries used in mobile phones years ago. They do not apply to the Lithium-Ion and Lithium-Polymer used in smartphones today.

What degrades Lithium-Ion and Lithium-Polymer faster is discharging heavily. The Battery University has conducted tests which show that the more you discharge a Lithium-Ion and Lithium-Polymer (referred to as depth of discharge) the faster it deteriorates. In short, if you fully discharge your battery once, this results in more wear and tear than charging it twice when it hits 30%.

2DoDTestImage credit: Battery University

I am not saying you should never let your battery go down to below 30%. It is a tool after all, so you should use it if needed for so long as the battery is still alive. But when convenient, try to recharge your battery when it is at 30% or more.

2. Do recharge frequently. Given that recharging at higher levels of remaining battery life results in less wear and tear, it makes sense to recharge frequently.

3. Partial charge is okay. Lithium-Ion and Lithium-Polymer do not suffer from the “memory effect”, so partial charges are okay. If you have an early morning meeting, and you drop by the office for a bit before an afternoon appointment, plugging in the battery for even half an hour will keep your remaining battery level higher at the end of the day.

4. Calibrate once every month or two. While Lithium-Ion and Lithium-Polymer do not suffer from the memory effect, at least not in the same way Nickel-Cadmium batteries do, continuous partial discharges create a condition called digital memory. Your smartphone does not really measure battery life, but really just estimates the remaining charge. Partial discharges decrease the accuracy of the device’s battery gauge. So once every month, or every other month, let the battery discharge to the cut-off point and then recharge. Once fully charged, leave it plug to the wall charging for another two hours. The power gauge will be recalibrated.

These four simple tips should keep your battery healthy until it is time to sign up for another two year contract, and take delivery of a shiny new smartphone.