Charge cell phone?

So far I've always charged my cell phone (and laptop), but recently many people told me that you can only charge the battery up to 80%.

What behavior is correct? My cell phone and laptop are relatively new, so I want to do everything correctly.

Never completely discharged and never fully charged. That makes sense, see deep discharge.

If you want to scconen the battery, this 80% rule would be correct yes.

but it seems that nobody does. The batteries today can handle that quite well. You can forget this rule more and more the newer the battery technology becomes

Otherwise, if you want the battery to last longer for 1-2 months, do that nonsense.

I charge from 15-95%.

The high voltage ensures that the electrodes degenerate, so you should only charge the battery to 80-90%. Unfortunately, that's bad, because the cell phones do not turn off by themselves at 90%. So you would have to constantly check whether the thing is already at 90%.

(I made a charging cradle on which my mobile phone is charged by inductive charge. From 90% the LED turns green. With a color sensor [TCS34725] an Arduino board can recognize that the LED is green and then switches via a MosFET The manufacturer could actually have implemented this internally as an option, in order to give the customer the freedom to choose whether he wants to fully pop his battery or not.

When the electrodes degenerate, the capacity of the LiIon cells decreases. So it is better to run around with 10% less capacity from the start than to have to be annoyed at some point that the battery only has 50% or 25% capacity.

The charging current is more important. With a high charging current, copper dendrites are formed, these are thin branches which then push through the membrane over time and lead to a self-discharge that becomes stronger over time. In the worst case, the battery explodes (was the case with Samsung), but often it just puffs up or just loses its charge so quickly that you throw away the cell phone or change the battery… Which is no longer that easy.

As a solution, I use the simple 500mA charger to charge my cell phone overnight. With a battery capacity of 2.5Ah, this theoretically takes 5 hours, but in practice it is more like 6 hours. But I don't care, you sleep during that time anyway.