max 713 charger not working with AAA batteries

Thread Starter

488 studios

Joined Nov 10, 2023
Hey, I built a 9v/AAA/AA charger with a max713 and a 15.4v 200mA solar panel, and it has a few problems I hope you guys can help with. I attached a schematic, SW1A-SW1F are a 6P3T rotary switch to select between 9v/AA/AAA. pins 1 are AAA, pins 2 are AA (LM317 constant current source), and pins 4 are 9v. SW2A-SW2C are a 3PDT toggle switch to select between 2 or 3 cells in AA/AAA modes. pins1 are 2 cells, and pins 3 are 3 cells. Firstly, it doesn't let more than 57mA through on the 9v setting, but when I breadboarded it,150-170mA were passing through. I set it to 174.8mA. It doesn't work on the AAA setting. both led's go out, and the voltage across the panel drops to 6.68V, and no current is passing through the battery holder. Also, on the AA setting, only 41.40mA (3 cells) and 47.65mA (2 cells). I set it to 201.6mA.



Joined Sep 17, 2013
a 15.4v 200mA solar panel
If those are the panel's ratings they are likely for when the panel is in full tropical sunlight at noon. Your current readings aren't surprising if the panel is putting out less than its maximum power and so limiting the charging current available.