Support for UPS-18650-Lite/UPS-Lite for Raspberry Pi

[gudvinr]

There is UPS module for RPi 4B/3B (UPS-18650-Lite and for RPi Zero (UPS-Lite)

Both use either MAX17041 (older rev) or CW2015 (newer ver) fuel gauge chips with I2C interface.

Those are not 100% compatible, and not address-compatible (MAX17041 uses 0x36 and CW2015 uses 0x62). However, their read registers are similar (VCELL and SOC are the same address, only VCELL resolution is different).

There's similar device already (pijuice) which has the same target device (Raspberry Pi) and operation conditions (Li-Ion battery directly attached to SBC).

[jimklimov]

PRs welcome :)

[gudvinr]

PRs welcome

What'd be the best course of action? I see that pijuice rawdogging I2C through smbus.

However, there are some records of people hooking up to /sys/class/power_supply/ with MAX17040 chips.

Is it possible to use /sys/class/power_supply/ as a driver for NUT? If so, then only overlay is needed for CW2015. This looks a lot cleaner since you don't need to create different drivers for different chips once it's done.

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I have a gut feeling that this is somewhat related to laptop batteries and there's a big change someone at some point already dug in this direction.

[jimklimov]

For battery integration/equivalence, you might be after #1869 (or #326 ;) ).

There was at some point integration with HAL (hardware abstraction layer) as a different way to use NUT drivers on a single system without upsd and upsmon, serving GNOME/MATE Power Manager instead - but it was deprecated as GNOME2 upstream wound down and GNOME3 did not have HAL, IIRC; see #1869, #99 and #105 for some context.

I am not sure this was a correct rip-out in the long run, as there are many derivatives of GNOME2 (e.g. MATE) still afloat specifically because many communities disliked the tectonic changes that came with the newer platform, and UPower seems to have succeeded HAL and is also afloat. So if anyone figures out tails and ends of the current situation and the older NUT HAL code to resurrect it, PRs are welcome :)