For others who see this and don’t want to build something themselves:

I make and sell an eink calendar (and smart display) for $149, complete with mobile apps and google calendar sync.

https://shop.invisible-computers.com/products/invisible-cale...

The display is 7.5 inch.

This is still a side project for me though I am thinking of ways to turn this into a self-sustaining business.

Why does it need a power cable? To me the main selling point of e-ink displays is that they should be able to last weeks if not months on a single charge...

I want to make a version with a battery. But I don't know when I will get this done. My goal is to make it last at least half a year. 6 months I think is the minimum standard for a thing that is supposed to hang on the wall and not be a hassle to babysit.

A battery adds a lot of complexity and cost for testing, certification and shipping. And it adds another failure mode. So I decided against it for the current version.

Thanks for your answer! Let me know when the battery version is ready :-)

This is pretty cool. May buy one and will provide feedback if I do.

That's really cool, I'm going to hack around with one too. Thanks for sharing.