Swappable battery on Lenovo x250

cherbert · 2015-07-18 07:11:30

Hi there,

Arch is working great on my new x250, "but"...
On windows (at least in principle) there's the possibility of hot-swapping the extra battery (never tried so far, though). I haven't managed to find any feedback on the web about this option in Arch Linux and I therefore ask here: is it supported? Is it working out-of-the-box or is there any trick to get it working?
In case, it would be great to have a small section on the X250 Wiki page

Trilby · 2015-07-18 11:33:14

I'm not familiar with the X250, but if I am reading this right my t450 has the same feature (edit: from a quick googling it looks like the same thing). There are two batteries. One removable, and another internal that it can run on for a period of time. This has absolutely nothing to do with the OS running and there is no need for the OS to support it - it's 100% in hardware.

acpi will detect both batteries and report on each of them 'out of the box'.

Have you tried removing the removable battery while running? Has it failed?

cherbert · 2015-07-18 17:09:18

Thanks for the information!

Trilby wrote:

Have you tried removing the removable battery while running? Has it failed?

I might have developed an instinct that prevents me from doing experiments with the battery, after ruining a few of them.. (EDIT: so, no, I haven't tried yet)
Anyway.. I had this doubt since on windows I saw that the hot-swap of the second battery can be done after kind of "unmounting" it, as usually done with usb drives. I was wondering if there's a similar command provided by acpi or something else that prevents any possible battery damage (if there's any such risk).

Another related question: is it possible to automatically start using the primary battery when, say, the secondary one has reached low charge (like 15%)? It seems to me that it doesn't happen by default (at least up to 15%, the minimum I let it go down to).

Last edited by cherbert (2015-07-18 17:12:41)

Trilby · 2015-07-18 17:15:07

cherbert wrote:

I might have developed an instinct that prevents me from doing experiments with the battery, after ruining a few of them
...
Another related question: is it possible to automatically start using the primary battery when, say, the secondary one has reached low charge (like 15%)?

Removing a battery cannot do any harm to it. The worst case is if that when you remove it, if the internal battery doesn't take over, you'll basically have a hard shutdown which will result in a loss of any unsaved data that you've been working on and will likely trigger an fsck on the next boot. But these are trivial too ... just save any open documents before you try this out.

As for the switchover threshold, I've never tried to modify it, but on mine the internal battery begins being drawn from before the removable battery is fully drained. Just watch acpi output and you can see this for yourself. For example, I'm on battery now, and my removable is at 66% while the internal has just dropped from 100 to 99%. The other day I had the removable battery at 10% and the internal was down to 85% or so. The internal battery is designed to take over when the removable is removed, or to suppliment the removable batter as it gets low, not to wait until it is dead.

Really, just try it out yourself.

Arch Linux

#1 2015-07-18 07:11:30

Swappable battery on Lenovo x250

#2 2015-07-18 11:33:14

Re: Swappable battery on Lenovo x250

#3 2015-07-18 17:09:18

Re: Swappable battery on Lenovo x250

#4 2015-07-18 17:15:07

Re: Swappable battery on Lenovo x250

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