The full form of VSR relay is Voltage Sensitive Relay.
A Voltage Sensitive Relay (VSR), as indicated by its name, is a type of relay that activates or deactivates based on the voltage level it detects. These relays are commonly used in multi-battery systems, such as those found in recreational vehicles (RVs), boats, and vehicles with auxiliary batteries, to manage the charging process.
How a Voltage Sensitive Relay (VSR) Works
The primary function of a VSR is to automatically connect or disconnect auxiliary batteries from the main charging source (like an alternator or solar panel) based on the voltage of the main battery.
Here's a basic breakdown:
- Sensing Voltage: The VSR continuously monitors the voltage of the primary (starting) battery.
- Connecting Batteries: When the primary battery's voltage rises above a certain threshold (indicating it is being charged), the VSR closes a contact, connecting the auxiliary battery to the charging circuit. This allows both batteries to be charged simultaneously from a single source.
- Disconnecting Batteries: When the primary battery's voltage drops below a different, lower threshold (indicating the charging has stopped and a load is being drawn), the VSR opens the contact. This isolates the auxiliary battery, preventing it from discharging the primary battery.
This automatic operation ensures that the starting battery always retains enough charge to start the engine, while also efficiently charging secondary batteries.
Key Advantages of Using a VSR
Using a VSR offers several benefits for multi-battery setups:
- Automatic Operation: No manual switching is required.
- Battery Isolation: Prevents the auxiliary battery from draining the starting battery.
- Efficient Charging: Allows simultaneous charging from a single source.
- Simple Installation: Generally easier to install than battery isolators with diode drops.
In essence, the Voltage Sensitive Relay (VSR) is a smart switch that manages power distribution between batteries based on voltage levels, ensuring reliable power for both essential functions and auxiliary loads.
