Do share more details - I am looking to do something like this in the kitchen, I have an old tablet I could use but I have always worried about the power it uses, given I would not be looking for 99.9% of the time. I am guessing the eInk uses a lot less power other than when changing?
eInk actually uses no power in "standby.
You can disconnect one completely from its power source and it’ll retain the display for literally, years.
Going by the picture, I’d guess it’s the backlight consuming the power.
From that web page at the link above:
I have an old ereader(like 7 years old) that still has the same page up even though I do not have a battery in the device.