Project notes 2022-10-26 (POC 3S LIPO)

Find the new GitHub Solder Fume Extractor Hardware repository where the KiCad design files will be hosted, together with other material during the progress of the open-source project. Thus feel free to use the material as you see fit, but see LICENCE.

I have also ordered a Sensirion SGP40 air-quality sensor to get some indicative readings. Will our HEPA and active carbon filter perform as expected? These experiments will come later when we flush down the main conceptual ideas around electronic design.

The chosen battery topology will influence a lot of the design. The power source, such as batteries in series or parallel with a boost converter and lithium cells with enough capacity, is rather bulky. 

That will influence the overall dimensions and cost to manufacture. Therefore I started today to evaluate a lithium 3S power pack solution that gives 11.1V nominally. I will continue with 3P/4P in the coming days.

I'm interested in, for example:

- Can it run the fan continuously for 8-10 hours?
- Will it recharge the 3S pack fully during the night?
- What changes in the fan's LiPo cell voltage during discharge?
- What is the required charge current?

I prefer to do some accurate tests since this strongly influences the final design. Luckily I have an RC charger that charges a 3S pack for coming tests. A first estimate is that the fan requires 2.4Wh (12V@0.2A), and this 3S pack with 24.4Wh (11.1V@2.2A) should theoretically be capable of 10.2 hours of power.