I'm trying to power a 24V DC motor using 2x 12V batteries, an Arduino and a Cytron MD10C Motor Driver. I followed the description on Cytron's website for how to connect the Arduino and the motor to the driver board. The 2 batteries are plugged in serie to provide 24V, then to the driver board power inputs.
On the first test with this schema, there were several issues, most importantly the GND wire between the Arduino and the driver board burned and some sparks appeared on the driver board when the motor was started using an Arduino signal. The Arduino also had some difficulties and kept rebooting.
I was wondering if this is a case of ground loop? If yes, how should the Arduino/driver board data section be isolated from the high current?
One of the battery is also connected to the Arduino to provide 12V input current (I now know this a bad practice, but left it on the schema in case it might play a role). In the future, the Arduino will be powered with a DC/DC switching regulator from the same 24V cables going to the motor driver.
Oddly enough, the schema works perfectly when the Arduino is powered by USB (from PC) and the driver board by 120V/5V AC wall converter. The motor driver also has test buttons which allow to test the board and power the motor without the need of an external MCU. When using those buttons, there are no sparks, nor burnt wires.
The Cytron datasheet does not indicate if the driver board is isolated, so I thought the motor current might go through it, then to the Arduino, then back to the battery.
The motor is a 24V DC motor (draws under 10Amps), similar to a windshield wiper motor. The batteries are 12V car batteries.
UPDATE:
Thanks for your answers. Below is a suggested schema using a DC/DC Step down regulator to provide the 12V to the Arduino. I also added fuses in series with the battery bank. I assume that the shared ground would remove the possibility of short-circuit?
Best Answer
Not a ground loop. But a short circuit:
Always use fuses with batteries.
Instead, you can make it like this, so that there is only one common ground:
Drawback is unbalanced load on the battery. Meaning the left battery depletes faster, possible damaging it when the set is deep discharged. I recommend a battery balancer, or a 24V-12V power supply instead.