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#1 2018-12-06 06:07:54

Giupo
Member
Registered: 2018-10-29
Posts: 3

Laptop does not charge if it drops to 0%

Hi, I have a problem with my Lenovo z500 laptop.
If I leave it in suspension mode, instead of turning it off, after 1 or 2 days it is completely discharged.
So far, everything is normal.
However, when I turn it back on and connect it to the current, it does not charge.
I just see with upower that the battery has "energy: 0 Wh" and "on-battery: no".
Yesterday for an hour the battery remained at 0% while it was charging, then after repeatedly recalling information commands as upower or acpi it started charging.
The other time, however, I managed to load only keep the computer turned on by the BIOS.
Once it manages to reach a 5% charge, I can also normally charge it from Arch.
What can I do to overcome this problem? Is it not possible to activate a "safe mode" to switch off the computer while it is in suspension if the battery drops to 10%?

I saw so many people complaining that the battery was burned because it was 0% and did not load, I'm afraid they had the same bug and they did not notice.
Thanks in advance to everyone

Last edited by Giupo (2018-12-07 13:35:25)

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#2 2018-12-19 21:35:56

madman_xxx
Member
From: PL
Registered: 2013-07-31
Posts: 28

Re: Laptop does not charge if it drops to 0%

It sounds like a normal behaviour which is not OS-dependent.

Let me tell you a little about Li-ION batteries. They are VERY efficient when it comes to energy storage. Almost all the energy provided is stored in cells and there's almost no heat dissipation. However, this is also their weakness - once the battery is almost full, it will convert all the energy to heat - this happens very rapidly and that's why those batteries explode.

To prevent such accident from happening, there is some protection circuitry around the battery - to check voltage, current and cell temperature. Charging process is strictly controlled. First stage of charge is a high-current one, after there's ca. 70% of capacity charged it slows down and by 95% it slows down even more. This circuitry also keeps track at what point of charging the battery currently is and how many charge-discharge cycles have been made. All those thresholds and sensors and data is heavy vendor-dependent.

Now, to your case. When the battery is empty, the circuitry most likely have lost track where it actually is - it may assume cells are empty, but must also assume that they're broken - that's why full current is not allowed, as it would cause overheat. The only way to check its state safely is to apply low current and see what happens. If the temperature does not go too high too quickly - it may resume charging at full current.

Is it not possible to activate a "safe mode" to switch off the computer while it is in suspension if the battery drops to 10%?

Depends on your definition of "safe mode". There's a thing called "suspend-then-hibernate" - systemd puts your laptop to sleep, sets a (configurable) timer when to wake it and when the time comes the OS hibernates it. Unfortunately it requires some configuration. See here: https://wiki.archlinux.org/index.php/Power_management

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