Looking at e.g. the Lolin D32 board or its siblings, the onboard charger for LiPo/Li-ion batteries does not seem to offer any undervoltage protection for the battery. Is it safe to assume that the board will simply cease to function due to a 'dead battery' before the cell voltage would drop too low anyway? The ME6211 regulator operates from 2V-6V so it looks like it will plod along merrily. Some say the ESP32 module itself will work down to 2V in extreme cases, meaning that the battery might continue draining down to about 2V in a worst-case scenario. Any thoughts?
I would expect the battery to drain all the way down to 0v eventually, if its left on.
You could use protected Li-Ion cells, or add your own DW01-like board (e.g. this one from eBay).
When the board stops working due to low voltage it won't stop drawing power.
wvmarle:
When the board stops working due to low voltage it won't stop drawing power.
But things like USB interfaces, regulators and pull up resistors tend to stay connected to the battery even when the processor itself has shut down.
PieterP:
You could use protected Li-Ion cells, or add your own DW01-like board (e.g. this one from eBay).
And when you check the details you find the cut-off is 2.4v to 2.5v typically.
I am not convinced that is safe, if it keeps happening repeatadly.