Part 1.3 : Charger/discharger completion… ish?

So, the next step was to install the PSU and wire everything, which went rather well. The connector did fit super nicely in the slot designed for it and I opted for only putting 2 screws instead of 4 on the PSU since it is pretty solid like that. I even printed some extra feet for the contraption to stand on.

With the PSU installed, It was now possible to do the first test, which… to be fair, went miserably bad. As soon as I plugged in the second cell, I noticed that all my charge circuits were going offline. After investigation, I noticed that the voltage would drop to 4.4v with 1 cell in, and to 4.0v with 2 cells in, making it just a bit lower than the minimum voltage input for the charge circuits. I had all kind of idea, including wondering if the switching mode power supply I got could have been bogus.

Two days of searching where the issue could come from, dismantling half of everything and trying to understand, I stumbled on a little detail that I missed. Inside the power supply, there’s a voltage selector switch for the transformer winding, well hidden INSIDE the cage. It was set to 220v while I’m on a 110v input here… I toggled the switch to the next position and retested with 2 cells. To my big surprise, the voltage stopped dropping and was super stable. I then proceeded to rebuild everything and getting ready for the “grand reveal” and it first test.

The first charge went a bit rough. I didn’t figured out that the TP4056 charge circuit was dissipating the extra energy if the battery charge was too low, making it extra toasty. Too toasty for my taste so I decided to add some small heat-sinks that I had laying around.

It does help a bit but I’m not satisfied with the passive dissipation. I’m considering adding an active cooling solution to help with that ‘problem’. I also realized that the power supply seems to be producing a bit too much heat for my taste so I’ll also have add fans to the PSU.

So, at the light of these last tests, I think I’ll have one last pass of enhancements to do on this bad boy but at least, now it’s usable (I’ve already tested a bunch of cells with it).

To be continued…