This is really cool! I don't remotely have the skills to pull this off, so I am in awe of what you achieved here. The explanations were pretty clear even for someone such as myself, but I was confused by one thing. If the device is powered by NiMH AAA batteries, why include the charging circuit, rather than just removing the batteries when needed to put into a dedicated charger?
Because this way, I (or my SO) doesn't have to unscrew the enclosure to get at the batteries. Usually, the batteries die, while the boy is in the middle of an audiobook. This way, we simply plug in a USB-C cable and everything keeps going.
