Solder Fume Extractor for the Stanley Case

I've made some pretty good progress on the Solder Fume Extractor, but I've also discovered what a pain in the arse prototyping can be.  I must have printed this thing at least twice over and some parts 8 times to get it to this point.  That however was the relatively easy part.  The electronics pack on this thing was designed to be somewhat modular, the thinking I had was that I could use it in other projects and it would also be easier to assemble since I could put it together outside the case and just install it.  Well that is somewhat true, but thanks to a bunch of mishaps (broken wires, mislaid wires, just looking like crap), I reworked this a couple times before I thought it looked right.  It would have worked but it was a bigger mess than it is now and I wanted to tidy up the wires a bit, which due to the small space I have to work with in the case is really a requirement more than a wish.  I then realized that the USB charger and protection board I bought was really designed to charge an 18650 or similar higher capacity Lion cell, not my puney 450mAh pack.  That matters because the bigger the battery capacity, the more charge you can pump into it, and this charger was set for 1A max current which is way too high for the battery I am using.  The good news is that somebody already read the datasheet and put together a great how to guide for a very similar board to what I am using, and they also broke down what the set resistor ("RProg") values mean.  I was able to confirm that my board matched up since the "RProg" resistor was "122" or 1.2Kohms by default.  Since I have a 450mAh battery, and I read that the safe max charge current is usually 0.5C to 0.7C, I figured that around 225mA would be a good safe max current.  Based on the table in the link about, I actually went down a bit since I only had 4.7K and 5.6K SMT resistors on hand, so I used the 5.6K's (which are labeled as "562").  That would provide about 215mA max current.  So I swapped the resistor and tested it, and it was pushing around 220mA at peak which seems pretty good (this was from a battery a bit more than 1/2 discharged).

I was a bit cautious when I tested the cell for the first time charging, for several reasons, including the obvious (that it was the first time charging so why not).  Happily the battery has been charging for the past hour and has gone from 220 mA to 90mA so the controller seems to be doing what it is supposed to.  I also confirmed that I can run the fan off the USB while plugged in and that the charge meter only displays properly when the USB is disconnected and the fan is off (which is what I assumed but it was worth confirming).  There is still some testing to do and a few more parts to print and test, but this one is almost done.

Quick update - I added a 1A fuse between the battery and the USB charging and protection board, and that is how I plan to leave it.  I took these measurements after installing the fuse to see what voltages the charging protection board would cut off the battery:

Battery Low Cutoff 3.04v (with 1A fuse in series with battery)
Battery After Charge 4.22v (with 1A fuse in series with battery)

These work for me, but I am still not really happy with the performance.  I tried a 5V regulator board and a 5V fan but the performance was only modestly improved, if that.  I think I need to go bigger on the fan to have adequate solder fume extraction, but this will work in a pinch.