You didn't like the answers you got already?
Didn't look at things really closely, but you need to connect all the grounds. Do you have any specific problems or questions?
Let's see the actual wiring.That relay board has 5V relays, not 12V.Make sure the relay jumper is removed.Add a reversed biased kickback diode across the motor.
Your relay board coils are 5v , they are not 12v.
As long as the motor and the Arduino are on completely separate circuits (which the relay can ensure - for some reason it seems you did connect the Arduino ground with the motor ground thus completely undoing this isolation) there will be no problem at all.The JD-Vcc is for powering the relay coil. The relay coil is electrically isolated from the relay contacts. The relay coil needs its own flyback diode (probably on the PCB of your relay module already).
You have the option of using the external 5v supply to power the Arduino if the Arduino is disconnected from the USB jack. In this case you would leave the jumper installed.However, this is a significant tradeoff where you have now defeated the isolation offered by the Otpo coupler.
I have to calculate if I have enough capacity to power Arduino for 15 days.
The final configuration (see earlier posts) requires to use the 12V battery to supply Arduino and the motor.