Two questions about battery LED behaviour and capacity upgrade

[Gasiro]

Hi, thanks again to the ZMK Design Guide again – my board is mostly working well now. However, I still have a few questions.

I’m using the same battery design as cornholius, including the HAC-006 battery and the same placement for the red LED.

I have two questions:

1. LED Behaviour:
   The red LED is supposed to stay on while charging and turn off when fully charged. But in my case, it turns off when the battery is around 90%, even though the battery percentage keeps increasing slowly (as seen on my computer). Is this normal behaviour?
2. Battery Capacity Upgrade:
   If I keep all charging and power management components the same as cornholius’s design, can I safely replace the 525mAh HAC-006 battery with a higher capacity one, like:

800mAh version
1850mWh version
Both are 3.7V Li-ion cells.

Are there any safety or compatibility issues with using a larger capacity battery?

Any insights would be greatly appreciated!

[Gasiro]

Another thing I don't quite understand is what WK1, WK2, and 1K3 mean in this schematic. They seem to be related to soft power-off, but how is that achieved? For example, is it simply triggered by pressing the Q, A, and Z keys simultaneously?

Also, since I’ve already added a physical SYSOFF switch near the battery, does that make the soft power-off function redundant in this design?

[ebastler]

The red LED is supposed to stay on while charging and turn off when fully charged. But in my case, it turns off when the battery is around 90%, even though the battery percentage keeps increasing slowly (as seen on my computer). Is this normal behaviour?

Hmm, I have not noticed this before. Might be an issue with the MAX. Try a couple of cycles. The chip might need to "learn" the battery still and accuracy can improve over time.

If I keep all charging and power management components the same as cornholius’s design, can I safely replace the 525mAh HAC-006 battery with a higher capacity one, like:

Yes, if they are the same dimensions I doubt they actually are >500 mAh though. Most of these aftermarket cells are scams. If such a large capacity battery were feasible in this formfactor, Nintendo would have used it.

Another thing I don't quite understand is what WK1, WK2, and 1K3 mean in this schematic. They seem to be related to soft power-off, but how is that achieved? For example, is it simply triggered by pressing the Q, A, and Z keys simultaneously?

Yes. If you have a physical button, I would omit both the connections and U5. The soft power off pins must all be on the same "strobe line" (driven matrix output), then allows the chip to use these pressed together to enter and exit deep sleep.