On/Off switch with power bank

[yuvke]

Hi, I know this topic has been discussed in length, specifically in:

• New to GPIO and RaspPi - how to implement an on/off button? #2154
• How to switch on and off your powerbank powerd Phoniebox? #1180
• Splitsheid blog posts - general phoniebox post and specific powerbank post

After reading all of the above here's my understanding of the options to implement an on/off switch when having a power bank:

1. Add a button directly to the GPIO pins

By following the instructions here and I'm guessing a little soldering, you can connect a button directly to the pi. However with this approach, while we are gracefully turning off the device, we will still be consuming power from the powerbank because the power is not cut.

2. Add an onoff shim and connect a button to the shim

This will cut the power completely but as a result, it could cause the powerbank to turnoff completely, and not turn on automatically again when the circuit is reconnected by the shim. However this seems to not happen all the time. At least from the instructions on the linked blog above and the discussions in the comments, it seems that sometimes turning on via the shim, will also turn on the powerbank. There's also an option of adding another circuit to the powerbank that would consume electricity with small intervals, essentially keeping it on. You can even buy a kit of this already.

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So if you've read this far, first of all thank you! 🙏
Here are my questions:

1. Is the above correct? Did I misunderstand something?
2. Is the power consumption difference between option 1 and 2 that dramatic? Can someone share some numbers from experience (e.g. battery would last 1 day of when the device is off without a shim and 10 days with a shim)
3. Are there more people that for them the shim was working with their powerbank (including turning on again) without any need of additional circuitry? Does it depends on the model of the battery? Would be great if we have a list of battery packs that were tested and worked with the shim without need to keep them on.

Thank you for all the help, I think that once all the data is collected from the community it would be nice to add a section about this part somewhere (if there is already a dedicated one I missed it obviously 😓 ). I'd be more than happy to offer a first draft.

Thanks again for reading and helping, and also for being a part of this incredible project and community.