Best practices for charging the PW2

[meeera]

Originally Posted by Outrager

http://www.wired.com/gadgetlab/2013/09/laptop-battery/
This article is for laptop batteries, but I assume it would be the same for the Kindle and smartphones/tablets since they all use Lithium-ion polymer batteries.

Stop charge at 80%. Charge at 40%. That's optimal, but doesn't mean people will do that since it's kind of annoying. Also, the Kindle lasts so long those extra battery charges might not even matter.

It's "optimal" only in terms of the number of discharge cycles one will wring out of the battery, not in terms of how long your device will last - since the article is talking laptops, not ereaders, and laptops are fairly commonly used plugged in. As the article says:

Battery University states that a battery charged to 100 percent will have only 300-500 discharge cycles, while a battery charged to 70 percent will get 1,200-2,000 discharge cycles.

So if I only need to use my laptop battery once a month, leaving it plugged in all the time except for that one day a month will mean I will get far more life out of my battery than I will expect to get out of my laptop - a theoretical 33 years (I doubt it, in practice!). Unplugging it every day using their rather onerous schedule would mean I would only get 4 years out of it. Or, if I was a heavy user and needed to cycle it twice a day, 2 years.

[jgsmith]

Laptops continue to run off the battery when plugged in, they are just charging at the same time. Leaving your laptop plugged in all the time, while practical, is not ideal for battery life. In the end, the objective is to have the battery remain functional as long as the device does. For most devices, this is relatively easy with minimal effort. For me, this is not so easy with laptops, and batteries need to be replaced every 18-24 months. But I probably use laptops more than the average person.

[FacebookVirus]

Originally Posted by jgsmith

Laptops continue to run off the battery when plugged in, they are just charging at the same time. Leaving your laptop plugged in all the time, while practical, is not ideal for battery life

When my laptop is plugged in, unless the battery is charging, I simply remove it.

I have no stats or sources, but that seems practical to me.

[imabuddha]

Originally Posted by FacebookVirus

When my laptop is plugged in, unless the battery is charging, I simply remove it.

I have no stats or sources, but that seems practical to me.

3 Comments:

1. Some laptops these days have non-user removable batteries.

2. Some laptops run in a reduced performance mode when plugged in with the battery removed. This is because their adapter is unable to supply enough power at maximum drain.

3. Keeping the battery installed even when plugged in provides UPS (power outage protection) functionality.

[FacebookVirus]

imabuddha, thanks for your comments. They're helpful. I wasn't aware of the changes in battery tech in recent years.

[HarryT]

Originally Posted by meeera

So if I only need to use my laptop battery once a month, leaving it plugged in all the time except for that one day a month will mean I will get far more life out of my battery than I will expect to get out of my laptop - a theoretical 33 years (I doubt it, in practice!). Unplugging it every day using their rather onerous schedule would mean I would only get 4 years out of it. Or, if I was a heavy user and needed to cycle it twice a day, 2 years.

Charge cycles are important for laptops, but irrevelent for eInk readers, where the number of charge cycles you'll get through under any likely circumstance is minimal. With a reader, the only battery effect that's of any consequence is the natural "aging" of the battery (the internal resistance of the cells increases with time). The clock starts ticking on the battery the first time it's charged, and it will probably have a lifetime of around 5-7 years.