Battery isolator
Encyclopedia
A battery isolator is an electrical device that divides direct current
(DC) into multiple branches and only allows current in one direction in each branch. The primary benefit of such an arrangement is the ability to simultaneously charge more than one battery from a single power source (e.g., an alternator
) without connecting the battery terminals together in parallel. This is beneficial because a weak or dead battery will drain the charge from a strong battery if both are connected directly together. The disadvantage to an isolator is added cost and complexity, and if a diode-type isolator is used (which is very common) there is additional voltage drop in the circuit between the charging source and the batteries.
Battery isolators are commonly used on recreational vehicles, boats, utility vehicles, airplanes, and large trucks where one battery is dedicated to starting and running the engine and another battery or batteries run accessory loads (e.g., winches, radar, instruments, etc.). 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: silicon
rectifier
packages, Schottky
rectifier packages, MOSFET
rectifier packages, and conventional mechanical relays.
Direct current
Direct current is the unidirectional flow of electric charge. Direct current is produced by such sources as batteries, thermocouples, solar cells, and commutator-type electric machines of the dynamo type. Direct current may flow in a conductor such as a wire, but can also flow through...
(DC) into multiple branches and only allows current in one direction in each branch. The primary benefit of such an arrangement is the ability to simultaneously charge more than one battery from a single power source (e.g., an alternator
Alternator
An alternator is an electromechanical device that converts mechanical energy to electrical energy in the form of alternating current.Most alternators use a rotating magnetic field but linear alternators are occasionally used...
) without connecting the battery terminals together in parallel. This is beneficial because a weak or dead battery will drain the charge from a strong battery if both are connected directly together. The disadvantage to an isolator is added cost and complexity, and if a diode-type isolator is used (which is very common) there is additional voltage drop in the circuit between the charging source and the batteries.
Battery isolators are commonly used on recreational vehicles, boats, utility vehicles, airplanes, and large trucks where one battery is dedicated to starting and running the engine and another battery or batteries run accessory loads (e.g., winches, radar, instruments, etc.). 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: silicon
Silicon
Silicon is a chemical element with the symbol Si and atomic number 14. A tetravalent metalloid, it is less reactive than its chemical analog carbon, the nonmetal directly above it in the periodic table, but more reactive than germanium, the metalloid directly below it in the table...
rectifier
Rectifier
A rectifier is an electrical device that converts alternating current , which periodically reverses direction, to direct current , which flows in only one direction. The process is known as rectification...
packages, Schottky
Schottky diode
The Schottky diode is a semiconductor diode with a low forward voltage drop and a very fast switching action...
rectifier packages, MOSFET
MOSFET
The metal–oxide–semiconductor field-effect transistor is a transistor used for amplifying or switching electronic signals. The basic principle of this kind of transistor was first patented by Julius Edgar Lilienfeld in 1925...
rectifier packages, and conventional mechanical relays.