sentences:  A battery isolator helps to ensure that the starting battery has sufficient power to start the engine and recharge the batteries if, for example, loads on the auxiliary battery (e.g., refrigerator or navigation lights) cause it to be drained, or if an auxiliary battery fails.Isolators are also used in vehicles with large, high-power car stereos and off road vehicles to accommodate high current loads such as a recovery winch.Several technologies have been used to achieve control of DC in this manner