How to jump start a car battery? Step 1: make sure the battery capacity of the mini car jump starter is above 50% (at least 3 indicator lights stay on). Step 2: connect the jump start cable to the drained battery of the vehicle; connect the red clamp to the positive '+' terminal and black clamp to the negative '-' terminal. Step 3: now attempt to crank start the engine. If the engine does not start, wait at least 10 seconds beforetrying again. Step 4: disconnect the mini car jump starter cable from the jump starter within 10 seconds after the engine has been successfully started. -
