Quote:
Originally Posted by emreka
People keep saying "phone/laptop manufacturers know what their doing" or "phone circuitry already does this" yet batteries keep dying after a few years. Charging your phone once to 100% is disproportionately more damaging than charging your phone twice to 90%. Think of it like filling and emptying a cardboard box to 100% vs. 80% 365 times.
There are studies regarding this, %40-80 is the most efficient cycle but you don't have to go out of your way, anything below 100% would help. Some laptops allow you to do this, some Samsung phones do this by default and that is how they can guarantee 95% battery retention after a year. Under normal circumstances you can expect 80% battery retention. Some of this extra 15% comes from the reserve power but most of it because there is a reserve power.
Other companies might be doing what Samsung is doing but not all, so it would be nice to have the option.
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Here's the thing, I
know all this. I've been using rechargeable batteries for a long time. I did a lot of research into Li-Ion batteries the first time I had to replace one in a laptop and was horrified at the price. I completely understand how this works and why you would do it. I just don't think it is worth it. If the device supports it, then great. But, someday, you are going to be stuck somewhere with a flat battery knowing that you sacrificed 20% of the runtime to allow the battery to last a few extra months. Hopefully the phone call you need to make isn't to your emergency number.
Another thing with this is: How do you know the device/battery isn't already doing this? The damage isn't done by charging to 100%. The damage is done by charging to to high a voltage. The 100% charge level represents a battery voltage. The exact voltage used depends on the charging circuit built into the device or battery. If the manufacturer chose a lower voltage for 100%, then it will already be doing this. Which is really all that Samsung is doing.
I'll stand by what I usually say: "Just use it". Anything you can do to extend the overall lifetime of a Li-Ion battery is a nuisance and means you aren't actually using the battery. And generally, doesn't have enough effect to be worth it. Use it as it is convenient, charge it when convenient.
And sorry, but what the hell is "reserve power"? Is there a second battery in the device that is used when the main battery runs out? Or have they just set 0% to a higher voltage and let the battery level run below that?