This is the soldering of the board
This is the setup instead
These are the connection with the motor driver:
VIN Battery positive cable
GND Battery negative cable
M1OUT1 motor black cable
M1OUT2 motor red cable
VDD 5V from arduino
M1IN1 PIN 12
M1IN2 PIN 11
PWMM1D2 PIN 13
I tried to connect the motor directly to the battery and it works. The measured voltage in this case is 11.74V (the battery alone had a voltage of about 11.8V when I start testing) and the measured current is 200mA (a value less then the 300mA from the datasheet).
So I tried againg the setup with the motor driver but the issue with the huge voltage drop still occours.
I tried also another 75:1 Metal Gearmotor 25Dx69L mm HP 12V that I have but it does not work.
I then found in my lab a 50:1 Metal Gearmotor 37Dx70L mm. I tried it with the motor driver and it works as expected modulating its speed and changing direction.
I also tested the driver without any motor and from the motor pin i measure the expected values.
So to summarize I tested 4 motors, the one linked in the first post, 2 different 75:1 Metal Gearmotor 25Dx69L mm HP 12V and one 50:1 Metal Gearmotor 37Dx70L mm. All of them works if directly connected to the battery. If I use the motor driver, instead, the two 75:1 motors don’t works anymore while the other two work as intended.
So I belive the code, the motor driver and the connections are working. The motors work too because they spin if connected to the battery. But when i connect the 75:1 gearmotors to the driver, the voltage drop is so high they can’t spin anymore.