Define upper and lower limit for charge state

Hardware Librem 5
1

Hi friends,

I want to use my Librem 5 only at home and it should stay at the charging cable. Since I red, that the battery has the best lifetime if

  • it is used regularly and
  • it is used in the range near 50%

I want the Librem 5 to automatically start charging, when the battery level reaches a level of 30% and it should stop charging when it reaches 70%. So the Librem charge state should oscillate between these two values without me doing something.

Do you have an idea how to implement this?

2 Likes
2

Sounds like a nice project. You can find some unsorted information here:

If you dive into the topic you could restructure the wiki page :slight_smile: .

If I remember correctly you’ll find information about setting some values in the BQ25895 charge controller of the librem5 if you search the forum as well. Those might not already have ended up in the wiki.

If you want to write to the wiki you’ll need to register an account which you can do on the git page. Do not wait for someone to confirm the account, but ask directly here or on one of the matrix channels. Otherwise it might take a long time until someone comes across your request for access.

2 Likes
3

Thanks for sharing the link. I learned 2 things:

  1. The battery is already not being charged to 100%, so it should last longer than most smartphone batteries already. Most batteries charge to 4.2V, and that is what the phone stops at, but the battery in the Librem 5 can go to 4.35v. So stopping charge at 80% in its current configuration is redundant. If someone takes out (or maybe just keep the kill switch on) the cell modem, it can be charged to its true 100% for a longer time between charges. This might be useful for someone who does not need cell service. Or only needs the cell modem after the battery has been discharged below a certain level. The cell modem may be able to operate outside of its spec, but I would keep a spare modem around and be prepared to change it yourself. Problems resulting from over voltage may not be obvious, like loosing connectivity every once and a while. If support is needed, let people know about the modification so that they can diagnose the problem accurately.

  2. It is possible to disable the red LED by changing a charge controller setting. Personally, I would rather have the charge controller inform me of its status. Also, if Purism’s support is needed, inform them of this change if anything strange happens with the battery so that they can diagnose the problem accurately.

1 Like