The market offers universal battery chargers for less than 15 euros, and if we increase the budget a little, we can access support for lithium batteries in different formats. However, those chargers always adopt a similar design: black rectangles with cheap plastic and low-quality LCD screens. The SPINC charger by 'Max.K' escapes that trap with an automatic system to charge AA batteries (electrically and physically), which also corrects polarity on its own and rejects alkaline batteries.
For some strange reason I keep buying USB chargers (they are like socks, I always need one), but when it comes to charging batteries/cells, a couple of years ago I invested in the Liitokala Lii-202. Today I use it in combination with one or two TP4056 modules (for those capricious batteries that refuse to cooperate), and honestly I never looked back.
Now, I won't deny that my charger is an avatar of boredom. Battery goes in, LED stays fixed, battery goes out. The whole process is manual (a detail I appreciate, because lithium batteries don't charge without supervision), however, nothing stops us from exploring other solutions. The SPINC project by 'Max.K' may be limited to AA NiMH batteries, but once we see it working... how could you not want one?.
SPINC: Automatic NiMH Charger for AA Batteries
The charger is based on a RP2040 (the same chip used by the Raspberry Pi Pico), and a Maxim DS2712 charger, both mounted on a custom PCB. The LCD screen is a Sharp LS027B7DH01A with a resolution of 400 x 240 pixels, and the servo responsible for all the movement is an EMAX ES08A. The software is simple but functional: the LCD screen has no touch support, so the configuration menu basically limits itself to date and time control (there is no web connection or NTP server access).
That said, the rest of the functions on the SPINC can be interpreted as 'smart'. In addition to monitoring voltage, temperature, and charging time, it also ejects the battery on its own once it's ready to use (a button on the back activates manual ejection). The charger holds a maximum of seven AA units (or AAA with the help of adapters), and has two additional details: It automatically corrects polarity, and rejects AA alkaline batteries.
Finally, the SPINC charger is open source, and all relevant files have already been published on platforms like GitHub, Thingiverse and Printables.
Sources: Hackaday.io, GitHub, Thingiverse, Printables
