Sierra BS11040 Voltage Sensitive Relay
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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 present—especially 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.
Shipping information
In-stock and OEM parts: ship same or next business day.
Locally warehoused items: ship within 1-3 business days.
Special-order items: timeline confirmed after order.
Returns & warranty
Returns & Satisfaction Guarantee
We stand firmly behind the quality of every product we sell. Your confidence matters to us — and we back it with a straightforward 30-Day Satisfaction Guarantee.
If you are not fully satisfied, you may request a return within 30 days of delivery. All returns must receive pre-approval prior to being sent back. Unauthorized returns will not be accepted.
To qualify for a return:
Item must be in new, unused condition
Product must be in its original packaging
All parts, components, hardware, manuals, and accessories must be included
Packaging must be undamaged and suitable for resale
Important:
Electronics are strictly inspected. No returns on open-box electronics. Exceptions may apply only with prior written approval. Any electronic unit that has been installed, powered, activated, or altered may not be eligible for return.
We are serious about product integrity — and equally serious about taking care of our customers. If there is ever a product issue, contact us immediately so we can make it right.
For return authorization, please contact our support team before shipping anything back.