Sierra BS11010 Battery Disconnect Switch – On/Off with Alternator Field Disconnect, 48V, IP66
Free returns on all eligible orders
You have 30 days to request a return. All sale items are final sale.
Sierra BS11010 Battery Disconnect Switch – On/Off with Alternator Field Disconnect (AFD)
A heavy-duty marine battery disconnect switch with a built-in Alternator Field Disconnect (AFD) circuit — the key upgrade over a standard On/Off battery switch. When the switch is turned off while the engine is running, the AFD disconnects the alternator field circuit before breaking the main battery connection. This prevents the voltage spike that occurs when an alternator loses its load suddenly, protecting the alternator’s diodes from damage that can cause premature failure.
Beyond the AFD, the BS11010 shares the same premium platform as the BS11000: IP66 rated, CE certified, ISO8846/SAE J1171 ignition protection compliant, glass fiber reinforced nylon enclosure, removable ergonomic knob, and flexible surface or panel mounting.
Key Features
- On/Off battery disconnect with Alternator Field Disconnect (AFD) protection
- AFD disconnects alternator field circuit before main battery connection breaks — prevents voltage spike damage to alternator diodes
- Maximum voltage: 48V DC
- Cable size: 4/0 AWG to meet ratings
- Tin-plated copper battery studs (M10) — 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
- Main battery disconnect on 12V, 24V, and 48V marine electrical systems with alternators
- Gasoline-engine compartments requiring ignition-protected switching
- Any installation where the battery switch may be operated while the engine is running
- New builds and refit projects requiring certified battery disconnect with alternator protection
Related Products
- Sierra BS11000 Battery Disconnect Switch – On/Off, without 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
- BEP 701 Contour Battery Master Switch
- Seachoice Battery Select Switch – Disconnect Isolator Cutoff, 12–50V
Parts Desk Insights
Best Use Case: The BS11010 is the right switch for any installation where the battery disconnect may be operated while the engine is running — which is the case on most boats. Turning off a standard battery switch with the alternator charging can send a damaging voltage spike through the electrical system; the AFD circuit on the BS11010 prevents this by disconnecting the alternator field first. If you’re certain the switch will only ever be operated with the engine off, the BS11000 without AFD is a lower-cost alternative. For multi-battery selector applications, see the Blue Sea Systems BSS-9003E.
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.