Automotive

A battery isolator is a device used in dual battery systems to manage the charging and discharging of multiple batteries. It ensures that the main battery (usually used for starting the vehicle) and the auxiliary battery (used for powering accessories) are charged properly and independently, preventing one from draining the other.

Types of Battery Isolators

Diode Battery Isolators:
Function: Use diodes to allow current to flow in one direction, ensuring that each battery charges independently.
Pros: Simple, durable, and reliable with no moving parts.
Cons: Can cause a slight voltage drop (typically around 0.7 volts), which can reduce charging efficiency.

Solenoid (Relay) Battery Isolators:
Function: Use an electrically operated switch to connect and disconnect the batteries. When the engine is running, the solenoid connects both batteries for charging; when the engine is off, it disconnects them to prevent draining.
Pros: No voltage drop, allowing full alternator output to charge the batteries.
Cons: Relatively more complex with moving parts that can wear out over time.

Voltage-Sensitive Relays (VSR):
Function: Automatically connects and disconnects batteries based on their voltage levels. When the main battery reaches a certain voltage, indicating the alternator is charging it, the VSR connects the auxiliary battery for charging.
Pros: Fully automatic operation, no manual intervention needed.
Cons: Slightly more expensive than basic solenoid isolators.