By God, it has not been used. God is my witness to what I say. Rafiq Al-Darb 150 Amp Dual Battery Isolator, new in its box, unused. A dual battery isolator, small in size (fits in the palm of your hand) and great in effect. Isolator dimensions: 10x9 cm only, with a thickness of 4 cm, and weighs only 60 grams. The easiest and safest way to install a backup battery, so that the backup battery can be used to start the car in case the main battery fails with the push of a button. How to ensure the device is working properly: 1- After correct installation, and if the car engine stops, only the red light (power indicator) should be illuminated. 2- Start the car engine. Within seconds, the blue light (charging indicator) will illuminate, indicating that the main battery is fully charged (13 volts) and that the backup battery is being charged. 3- If the blue light (charging indicator) does not illuminate, increase the engine speed to generate more electricity. 4- During the charging process, stop the engine and turn on all car lights and anything that consumes electrical power. The device will detect the power consumption from the main battery. After 60 seconds, and after the voltage drops below (12.8 volts), the blue light (charging indicator) will turn off, and the device will disconnect the two batteries. Isolator operating modes: - Automatic operation: If the device is installed correctly and its operation is checked, the device works automatically to charge the backup battery. - Manual operation: In case the main battery is depleted of its electrical charge and the backup battery is charged. You can jump-start the car using the two batteries: 1- Press the (Over Ride/set) button, and the isolator will connect the two batteries together, and the green light will illuminate. 2- Start the car, and then the isolator will return to automatic mode. 3- You can press the (Over Ride/set) button to switch the isolator to automatic mode, but it will not switch to automatic mode if the voltage in the main battery does not reach 10 volts. Price: 350 SAR Its price from Rafiq Al-Darb is 398 SAR, excluding shipping costs.