The power consumption you're observing on your M5Paper when the EPD (Electrophoretic Display) is idle is indeed higher than expected. It's unlikely that you have a defective unit, as the behavior you described is more likely related to software or driver optimization.
EPD displays typically have low power consumption because they require power only during screen updates. Once the image is displayed, the EPD consumes very little power to maintain the image. However, it's possible that the EPD driver or the default app on your M5Paper is not optimized for low power consumption during idle periods.
To optimize the EPD power consumption during idle periods, you could try the following steps:
Check for firmware updates: Ensure that you have the latest firmware version for your M5Paper. Manufacturers often release firmware updates that include optimizations and bug fixes that can improve power efficiency.
Look for power-saving options: Check if there are any power-saving options available in the EPD driver or the default app settings. Some devices offer options to reduce the refresh rate or enable power-saving modes for the EPD.
Consider customizing the EPD driver: If you have experience with programming and access to the EPD driver source code, you can explore the possibility of customizing the driver to optimize power consumption during idle periods. This might involve tweaking the refresh mechanism or implementing additional power-saving features.
It's worth noting that while EPD displays are generally power-efficient, power consumption can vary depending on factors like display size, color depth, and the specific implementation of the EPD driver. Therefore, it's not uncommon to encounter variations in power consumption between different devices or even different firmware versions.