Sierra BS11020 Dual Battery Selector Switch – 1/2/Both/Off, 48V, IP66, Ignition Protected
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Sierra BS11020 Dual Battery Selector Switch – 1/2/Both/Off
A 4-position dual battery selector switch for marine electrical systems with two battery banks. The four positions — Battery 1, Battery 2, Both, and Off — let you select which battery bank powers the boat, combine both banks for starting or heavy loads, or disconnect completely. This is the standard configuration for most twin-battery marine setups, where one bank is dedicated to starting and the other to house loads.
Built on the same premium platform as the BS11000 series: IP66 rated, CE certified, ISO8846/SAE J1171 ignition protection compliant, glass fiber reinforced nylon enclosure, removable ergonomic knob, and flexible surface or panel mounting. M8 studs accommodate the dual-battery wiring configuration.
Key Features
- 4-position selector: Battery 1 – Battery 2 – Both – Off
- 2 battery inputs for dual-bank systems
- Maximum voltage: 48V DC
- Cable size: 4/0 AWG to meet ratings
- Tin-plated copper battery studs (M8) — stud torque: 120 lb-in
- Removable ergonomic knob for safety isolation
- Interchangeable knob labels for easy circuit identification
- Glass fiber reinforced nylon enclosure — corrosion-resistant
- Removable windows on all four sides for flexible wiring access
- Surface or panel mount options
- Includes 4× M4×35 mounting screws
- IP66 rated — dust-tight and protected against powerful water jets
- CE certified
- Meets Ignition Protection Standard ISO8846 / SAE J1171
Compatible Applications
- Dual-battery marine electrical systems with dedicated start and house banks
- 12V, 24V, and 48V twin-battery configurations
- Gasoline-engine compartments requiring ignition-protected switching
- New builds and refit projects requiring a certified dual-battery selector switch
Related Products
- Sierra BS11000 Battery Disconnect Switch – On/Off, Single Battery
- Sierra BS11010 Battery Disconnect Switch – On/Off with AFD
- Blue Sea Systems Battery Switch – 2-Position, 350A (BSS-9003E)
- Blue Sea Systems 4-Position 300A Battery Switch (BSS-6007)
- BEP 700 Easyfit Battery Master Switch
- Seachoice Battery Select Switch – Disconnect Isolator Cutoff, 12–50V
Parts Desk Insights
Best Use Case: The BS11020 is the right switch for the standard twin-battery marine setup — one starting battery and one house battery — where you want to select between banks, combine them for engine starting, or disconnect completely. The Both position is particularly useful for emergency starting when the primary bank is low. The IP66 rating and ignition protection certification make it suitable for exposed helm locations and gasoline-engine compartments. If you only have a single battery bank and need a simple On/Off disconnect, the BS11000 is the correct fit. For a single-battery switch with alternator protection, see the BS11010 with AFD.
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.