I wonder what's the point to run.batteryless? With such a small power budget, the device should accumulate energy when it can harvest more than it needs to consume, and use it when the lighting conditions deteriorate. It would only take a really small battery, but would seriously increase usefulness.
i've discussed the reliability problems of batteries further in https://news.ycombinator.com/item?id=40805573, but, as an intuition pump, consider that when cellphone repair shops advertise particular repairs, the particular repairs they advertise most are battery replacement, charging port replacement, and broken screen replacement
So use a battery of a standard form factor and make it easy to replace. E.g. one AAA battery per device is easiest. Most coin-sized lithium batteries are also rechargeable, explicitly or implicitly.
What do you mean by implicitly? Last time I checked, most of button/coin-like batteries (CR2032 and the such) aren't know to be rechargeable, unless you specifically get rechargeable ones.
you don't seem to have really understood my points, because you aren't engaging with them; as it happens, you're also mistaken about coin-sized lithium batteries (though any battery can be slightly recharged)
