Quality 200amp Redarc dual battery system links the main battery to the auxiliary battery once the duel battery system sensors the alternator is charging. Once the system sensors charging falls below 12 volts it will separate the duel batteries. For example when the car is started the two batteries are linked and when the car is turned off the two batteries are separated.
The batteries are linked using 12mm heavy-duty cables. The larger cables are used because there is less resistance between the batteries for added power supply for winching and the kit also has an option of jump starting the vehicle from the auxiliary battery with a push of a button.