Edge electric connections to Garmin Charge Power Pack

I've opened a GitHub repo. Will update slowly
https://github.com/mk4th/GarminEdgeCharger

Please ask what do you like me to test

There's this charging cradle that I use to charge my 830 at home: https://www.thingiverse.com/thing:4806657

It only uses two of the charging contacts on the back of the computer. There are a number of small problems. Annoyances really:

• After you pull the computer off the charger and turn it on, it shows an error message that it lost power from the battery pack, even if it's at 100%. That's pretty obvious and not really a problem in this case, but you have to dismiss the error message every time you charge the computer.
• If the computer is off when you put it on the charger, it will turn the screen on briefly then turn it off. This usually isn't a problem, but it also connects to my Varia radar and turns it's light on. Normal connection mode would just glad the light, but I guess the computer turns off before turning the light off. The fix for this is to hit the power button on the computer to turn it on (before or after putting it on the charger), let it finish connecting to the Varia, then turn it off after putting it on the charger and after the Varia light turns off.
• The cradle cannot be used for any USB communication, namely for connection to Garmin Express to update maps. I think everything else can be done over Bluetooth.

Edit to add:

I assume some of the other connection pins are for the battery management, of course.

The main reasons why the computer needs to communicate with the battery management is probably to turn the high current charging on so that the charger won't self discharge as fast, and so it won't create a hazardous condition when it is stored- say in a bag with conductive items nearby that could short across the pins. Maybe there's also an option to display the power pack's battery level.

All of those reasons would be helpful- but not necessarily required- for a battery control module for a self-designed battery pack. They're not necessary for the charging cradle that's plugged into a wall outlet power brick unless one expects conductive items to short across it when the computer isn't connected.

Finally, note that the Edge Power Mount (which was announced with the Edge Explore 2 in July 2022) also allows you to charge the computer through the power pins, preserving the water resistant integrity of the computer. Waterproofing the connection to your power pack is a separate issue.

Edit: *gulp* that's the same price as the Charge Power Pack battery. I assume the reason for the Power Mount is for the convenience for anyone who has a compatible ebike.