Librem 5 "battery fully charged" audio indication


#1

Since a smartphone battery has a limited lifespan of charging cycles
I assume that leaving a smartphone connected to a wall power outlet
hours after the battery is 100% charged, is a waste of charging cycles.
Is that so ?
If so, can Librem 5 designers integrate an audio signal to alert the user
that the battery is 100% charged.
This audio signal can be a unique sound or a verbal note repeated 2 or 3 times.
What is your opinion ?


#2

Will the battery be easy replaceble?


#3

First of all, yes, the battery will be user replaceable.

Second, caring for LiPoly/LiIon batteries has become sometimes more of religion than engineering :slight_smile:

The facts that I know are:

  • they do not like to be discharged low
  • they do not like to be recharged too often
  • the last about 10-20% of charge cause the most wear

Years of experience of Thinkpad users where the charge controller can be software controlled show that battery packs can be kept alive a lot longer when a) avoiding recharge cycles and b) not charging them to 100% every time they get charged. Of course this is no guarantee for cells not to fail but it seems to help a lot.

So giving an alarm beep when reaching 100% does not help. Once it is charged it is charged and nothing can be done anymore. Every charger logic must avoid to continue pumping energy into them anyway since Lithium based batteries could be severely damaged otherwise, up to burning / explosion. So after reaching 100% the charger will stop charging and the device gets powered from the charger, which should keep the battery at 100% - without continuing to charge it. It just remains full, no power is taken from it.

Long story short in the Librem5 we will implement a smart charger chip that can be controlled by software - to some extend. Of course cut-off currents and voltages for our battery may get hard coded to avoid them being changed and create dangerous situations, but the charging behavior will be user changeable, like when to stop starching, when to start charging again and some other parameters. If you do not need the full charge you can e.g. select to charge it to 90% only and not to recharge it before dropping below, say, 60%. This will save your battery quite some stress and it will last longer.

The details of this will be described in appropriate documentation we are creating while we make progress, some of you can already find on:
https://developer.puri.sm/

Cheers
nicole


How long is the lifetime of Librem 5?
Providing an AC power cable with Librem 5
Librem 5 — Promise Delivery Chart
#4

Thank you for your detailed response


Providing an AC power cable with Librem 5
#5

That’s excellent news! :slight_smile: wish we could have something similar for the laptops, too!
Seems to be a recurring topic:



#6

yes the general consensus for li-ion to not let reach 95% and not let drop bellow 25% but just to be safe keep it charged between 33-90 % it’s quite hard on just removable batteries you have to have hot-swapable batteries system in the phone to be able to not stress about these levels.

with removable non-hotswapable batteries you are like - ok 8 AM all good 95% then at 4 PM you’re like - oh shit it’s 25% and i have still got to make phone calls and travel around before getting home. on hot-swapable you’re like a boss - 33% whatever no problem just take the almost empty one out and slide another in. recharge both at home.

the audio indication is not of much help - better to have an auxiliary dedicated led symbol with 8 bars - 12.5 % each increment up to close to 90% rest is deduction.


#7

Some of us do :wink:

Totally. It took 2 years for my battery to lose 75% capacity. Then I set the charge limit to 80% and I haven’t noticed any further drop over the last 3 years. Like some kind of a miracle!


#8

On Android I am using a Magisk module (https://github.com/Magisk-Modules-Repo/acc) to control charging parameters. According to its documentation, the kernel is taking care of the charging. Which means that charging my phone turned off, the charging parameters are not applied. My thinkpad notebook instead has its charging control on firmware level. The battery was charged the same way in Windows, Linux or even turned off.

I wonder, if this smart charging chip will be below the os layer like the thinkpad implementation and charging the librem 5 being turned off is behaving the same way as turned on.