Re: Charge speed vs battery life

Siard, 2024-07-16 12:35:

In order to extend the life of the battery, some people say that it is
best to charge it at a slow speed.
Others say that quick charge is fine as long as the battery does not
become too hot.
Yet others claim that quick charge is even _better_, because the charge
time is shorter.

The latter one makes no sense since high temperature during charge is
always bad for the battery. Also the electrodes in the battery degrade
faster the more power they have to transfer.

I always thought that a charge current of about 1000 mA is most ideal,
but AccuBattery shows this speed as very low and in red, as if it is bad.

1000 mA at 5 Volts would be around 5 Watts. Even with USB-PD and 9 or 18
Volts this would be only 18 Watts. Modern Smartphones usually charge
using 30-60 Watts depending on the number of batteries used. Higher end
phones have two or more batteries in parallel so they can use higher
charge power which is distributed evenly along multiple batteries

I saw a review of smartphones where a charge time of 1.5 hours was called
'long', whereas I always considered 2.5 hours as normal.

Well, nowadays some devices manage to charge nearly 100% within less
than an hour. But I consider 1-2 hours as normal for a charge from
nearly 0% to 80-90%.

Does anyone know what the most ideal charge speed would be?

There is no generic "ideal charge speed". Or in other words: any speed
is ok, as long as the battery will not get damanged by the charge process.

The device manufacturer designed or choose the charge controlling
procedure and the battery which you can not change. Usually mobile
devices are designed to work at least 2-3 years without any major
degradation of the batteries.

Also the charge process often adaptive: it will start with a higher
current in the beginning and as more the battery is charged, the current
will be reduced. Some devices will have adaptive charging during night
time when the device is not used regularly, so the charging process will
take a couple of hours but only with reduced current to increase the
battery life.

As a rule of thumb: rechargable LiIon batteries can take 500-1000 charge
cycles before the capacity starts to degrade. So when you recharge the
device from nearly empty to nearly full every two days this means around
3-6 years of use without any major capacity loss. But even after that
time, the capacity loss is gradual and you may notice that the battery
only lasts for 30 hours and not 40 hours as before.

Also keep in mind that apps like Accubattery can only measure the charge
but not change it without root access.

--
Arno Welzel
https://arnowelzel.de