CommentStreams:09c88bfe77dcc3a737c355c0fe98fe0f

I am not sure if this is helpful as it's not a very technical answer, but I have purchased and used a few of these boards (with skepticism) and the battery (even at a theoretical 3.7 though I think the 18650 charges to 4.2v or something) lasts quite a while. I have build a few different projects from them - one drove some color-changing LEDs for a while (I did not run it until the battery ran out, so I can't say how long it lasted) but another was a counting device that ran a back-lit LCD and an optical encoder for several hours at a time (at least 3 hours at a time) without running out of battery power.

As part of that project, I actually wanted to add a battery meter - I hoped that maybe there was some on-board circuitry I could use (voltage divider) and attach to an analog pin, but I don't know of any (anyone know if it's there, perhaps? I did not want to have to add a prototyping board to my project just to monitor the battery. (I can't monitor it post-voltage regulator as that will *always* be 3.3v until it isn't :-))