Take the battery out of the battery tray. Always use heavy duty wires when connecting batteries in parallel.

Can I Connect Lithium Batteries In Series
How to connect battery. Disconnect the negative cable from the engine block. Take another wire and connect the negative post of the first battery to the negative post of the second battery. Clean both battery posts with a wire brush. Connect your positive and negative wires to one battery and run your application. There are two cables that connect to your battery. Take a jumper wire and wrap it around the positive terminal of the first battery.
Using a combination wrench or a socket and ratchet remove the battery hold down clamp. The positive cables end connector is often either painted red or has a red plastic clip attached to it. Remove the positive cable from the solenoid relay or starter. New car owners often have difficulty in determining what each step involves and even more importantly figuring out the order in which the steps should be followed. Batteries are heavy so grab from the bottom using both hands. The second cable is a ground cable which connects the negative terminal of the battery to the body of the car.
It runs to the engines alternator. Connect the other end to the positive terminal of the second battery. It means that the first head of the battery is connected and the tail is connected. How to connect a car battery safely when it comes to how to connect a car battery as safely as possible the installation process can be a challenge especially if you have never tried doing something like this before. Detach the positive red battery cable from the battery using the same method. The shunt voltage is equal to the individual battery voltage and the current is equal to the sum of the battery currents.
Connect the positive cable to the solenoid relay or starter. That is the positive poles of all the batteries are connected and the negative poles of all the batteries are connected.