Sierra BS11040 Voltage Sensitive Relay

Sierra BS11040 Voltage Sensitive Relay (VSR) is designed for 12V dual-battery systems, automatically combining batteries during charging and isolating them when charging is not present. With a robust glass fiber reinforced nylon enclosure and visual status indication, it helps support efficient charging and battery protection in marine-style electrical setups.

Key Features

• Automatically combines two batteries when charging and isolates the two batteries when not charging
• 12V nominal system with specified voltage thresholds (Combined: 13.3VDC, Open: 12.8VDC)
• High current capability: 125A continuous / 140A intermittent
• Low power consumption control: 10mA standby / 330mA engage, with 0mA storage mode
• No voltage drops comparing to battery isolator diodes (0.6V)
• Built-in LED indication when VSR is engaged
• Remote LED port for remote VSR status indication
• Robust glass fiber reinforced nylon enclosure
• Surface or panel mount installation options
• Storage mode allows zero power consumption when the engine is off
• CE and IP67 certifications

Product Compatibility

• 12V dual-battery charging/combining applications where batteries should be isolated when not charging
• Marine and other DC systems using a voltage-sensitive battery combining relay strategy

Product Details

• Nominal Voltage: 12VDC
• Combined Voltage: 13.3VDC
• Open Voltage: 12.8VDC
• Continuous Current Rating: 125A
• Intermittent Current Rating: 140A
• Power Consumption: 10mA (Standby) / 330mA (Engage), 0mA (Storage Mode)
• Function: Automatically combines two batteries when charging and isolates the two batteries when not charging
• Voltage behavior: No voltage drops comparing to battery isolator diodes (0.6V)
• Enclosure: Robust Glass Fiber reinforced Nylon enclosure
• Indication: Built-in LED indication when VSR is engaged
• Remote indication: Port for remote LED indicating VSR status
• Mounting: Surface or panel mount options
• Certification: CE and IP67 Certifications
• SKU/Variant: 11-BS11040

Parts Desk Insights

Best Use Case: Use this VSR for dual-battery systems where you want charging to automatically parallel the batteries, then return to isolation when charging is not presentespecially when you want low standby drain and a true storage mode when the engine is off.

Common Issues: When installing voltage-sensitive combiners, most problems come from wiring to the wrong battery/side of the system or missing the recommended remote indication connections. Also confirm mounting/clearance and that the remote LED wiring matches the intended port so status indication is correct.

Related Products & Accessories

• Relays & Solenoids – Browse the Relays & Solenoids category for additional battery switching and protection components that pair with your system.