TL;DW: Fast charging over 2 years only degraded the battery an extra 0.5%, even on extremely fast charging Android phones using 120W.
And with that, hopefully we can put this argument to rest.
TL;DW: Fast charging over 2 years only degraded the battery an extra 0.5%, even on extremely fast charging Android phones using 120W.
And with that, hopefully we can put this argument to rest.
Do you have more info on that?
A cell’s voltage will change with how much energy it stores, but if you keep applying current to force more charge to move you can cause voltages to be quite far outside of the proper range. However you don’t want to do this as at minimum you are damaging the materials in the cell, or worse, cause a significant safety hazard where the cell could catch on fire.
You can look at the Discharge Curve of a cell which compares voltage vs capacity, as a rule of thumb, essentially the steeper the curve changes, the more damage you are doing to the cell by operating in the range.
Lithium-* batteries don’t actually have any specific useful numbers. It’s something like this (the actual numbers are pulled out of my ass and depends on battery time and test parameters and even then I’m simplifying):
At 0 volts, the battery is dead.
At 1 volts, the battery is practically dead.
Discharging to 2 volts kills it after around 100 times.
Discharging to 3 volts kills it after around 10 000 times
Discharging to 3.5 volts kills it after 100 000 times
Charging to 4 volts kills it after 100 000 times
Charging to 4.2 volts kills it after 10 000 times
Charging to 4.3 volt kills it after 1000 times
Charging to 4.4 volts kills it after 100 times
Charging to 4.5 has s significant chance of it catching fire
Now choose how many charge cycles you want it to survive, and you know which voltage to consider 0% and which to consider 100%. The bigger difference, the bigger capacity with the same battery.
This is why a phone with 0% battery can tell you that it’s out of battery.
You can also adjust what “killed” means. Is it when battery capacity is reduced to 80%? 50%?
I have to repeat - the numbers are not accurate, and this is strongly simplified.
It’s just an illustration of what 0% and 100% means it’s just where you are on the useful range, according to the manufacturers definition of useful.
The battery has a charge curve. What does the most wear or damage to the battery is the ends of the curve - either deep discharging the battery or charging it up fully to the point where it cannot take any more charge. It’s up to the manufacturer where they want to put 0% and 100% on the curve - to protect and extend the life of the battery most manufacturers don’t put 0% and 100% at the extreme ends of the curve.
Best source I can find: https://eugen-barilyuk.medium.com/how-i-realized-android-battery-percentage-wasnt-serious-enough-0310e484d874
3.7v is 0%, 4.2v is 100%. But a lithium battery can go higher and lower, it’s just that doing that can harm the battery, perhaps spectacularly. OEMs just narrow the voltage range to extend life. When you set a charge limit, it narrows that range further.
Something is off with the link’s measurements. 3.7V is a li-ion cell’s nominal voltage, not its lower limit. Typical operating range is 3.0V - 4.2V. No battery chemistry I’m familiar with would have a lower cutoff as high as 3.7V.
You’ll find that based on 3.7 - 4.2 that most li-ion batteries are indeed charged from 0-100 and not 20-80 as you previously claimed. Manufacturers have no reason to overprovision consumer products that are made to be replaced in 5 years or so.
Yes, that’s what I said. You could go higher and lower, and it would be reasonable to do for a short-life device, but they reduce it to extend the life. Mapping voltage to percentage is arbitrary.