Hello everyone,
I was trying to control dc motor with double relay module connected to arduino uno (whole thing is powered by two 9 volt batteries in parallel configuration)
I noticed that every time the relay changed the polarity the motor became a bit slower until it completely stopped
Please tell me why is this happening and also how to fix it
Welcome to the forum
PP3 batteries by any chance ?
They are designed for low current applications such as smoke detectors, not high current devices like motors. Have you measured the battery voltage whilst the motors are running ?
Consider using 4 or 6 AA cells in series as a power source