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Blue Sea 500A HD-Series Heavy Duty 4 Position (OFF/1/2/1+2) Battery Selector Switch w/ AFD
Blue Sea 500A HD-Series Heavy Duty 4 Position (OFF/1/2/1+2) Battery Selector Switch w/ AFD
Make-before-break changeover, ignition protected, AFD support
Key features: 4-position rotary dial (OFF, 1, 2, 1+2), Ignition protected marine design, Heavy-duty construction for high amperage.
Highlights:Input 1 Terminal: Connection stud for first battery bank,Input 2 Terminal: Connection stud for second battery bank,Output Terminal: Common output connection to load or engine,Mounting Hole: Corner mounting point for secure installation. 
Regular price
$188.00
Availability:
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DESCRIPTION
Confident control of dual battery banks for marine and RV power
Managing multiple battery banks on a boat, 4WD or caravan often means balancing two priorities: keeping critical loads powered and protecting your charging system. The Blue Sea HD-Series 4-position battery selector switch with AFD is built for high-current installations where dependable changeover and battery isolation matter. It gives you clear, manual control to run from Battery 1, Battery 2, both combined, or OFF—helping you reduce the risk of accidental battery drain and simplify troubleshooting on-board electrical systems.
For Australian conditions and demanding marine environments, this selector switch is designed to suit heavy-duty cable runs and high-load circuits. The HD construction, robust terminals and practical mounting options make it a strong fit for new installs and upgrades where reliability and serviceability are priorities.
Why AFD matters when switching under charge
When an engine is running, abruptly disconnecting the alternator can contribute to voltage spikes that may stress sensitive electronics. This model includes AFD (Alternator Field Disconnect), supporting safer switching practices for systems that require alternator field management. Combined with a make-before-break contact design, it allows you to transition between battery banks without the momentary loss of power that can reset devices such as radios, navigation equipment and onboard control modules.
Built for marine safety and installation flexibility
On petrol-powered vessels, component safety ratings matter. This switch is ignition protected, making it suitable for installation in engine spaces where ignition protection is required. The enclosure is also designed for practical installs, offering surface or rear panel mounting to suit dashboards, switch panels and electrical lockers. With clearance and terminal design intended for large battery cables, it supports tidy, professional cable routing in tight compartments.
Ideal applications
This heavy duty battery isolator/selector is commonly used in:
- Boats with house and start battery banks
- 4WD touring setups with dual batteries and accessory loads
- Caravans and camper trailers needing selectable battery sources
- Workboats and commercial vehicles where downtime and power interruptions are costly
Key features
- 4-position selector for OFF / Battery 1 / Battery 2 / Combined operation
- AFD support to assist alternator field disconnect requirements
- Make-before-break switching to help minimise power interruption during changeover
- Ignition protected design for use on petrol-powered boats where applicable
- Flexible mounting options for cleaner installs and easier servicing
- Heavy duty terminals designed to suit large battery cable connections
Practical benefits for owners and installers
Compared with lighter-duty battery switches, the HD-Series format is aimed at high-current systems where heat, vibration and frequent use can expose weak points. By giving you a clear operating mode and robust changeover, it can help reduce nuisance shutdowns, simplify battery management, and support safer isolation during maintenance. It’s a straightforward upgrade for anyone looking to improve confidence in their marine electrical system, dual battery setup, or auxiliary power distribution.
If you’re building or refreshing a system, pair this switch with correctly sized cables, appropriate circuit protection and a wiring layout that matches your alternator/charging method for best results.
SKU: BS-3003B
SPECIFICATIONS
Specifications
| Switch Type | Selector 4 Position |
|---|---|
| Color | Grey |
| Switch Positions | 4 |
| Battery Combine | Yes |
| Alternator Field Disconnect | Yes |
| Maximum Voltage | 32V DC |
| Terminal Stud Torque |
220 in-lb (24.86 N·m) (approx. 18.3 ft-lb; reference only) |
| Continuous Rating | 400A |
| Intermittent Rating | 700A (5 min) |
| Starting Rating (30 sec) | 1600A |
| Battery Inputs | 2 |
| Cable Clearance For 4/0 AWG Cables |
1.10in (27.94 mm) (reference only) |
| Cable Quantity to Meet Ratings | Two Cables / Terminal |
| Cable Size to Meet Ratings |
4/0 AWG (120mm²) (AWG vs mm² is an approximate equivalence; reference only) |
| Mounting Holes |
Accept 1/4" (M6) Screw (1/4" ≈ 6.35 mm; M6 is 6 mm; reference only) |
| Stud Material | Tinned Copper |
| Switching Rating | 25A |
| Terminal Stud Size |
1/2" (M12) (1/2" ≈ 12.70 mm; M12 is 12 mm; reference only) |
| Weight (min / max) |
1.25–1.25 lb (0.57–0.57 kg) (approx. 570 g; reference only) |
| SKU: | BS-3003B |
| Model #: | BS-3003B |
| MPN: | BS-3003B |
WARRANTY
Blue Sea Warranty Policy
Blue Sea Systems products sold by us are supplied with a warranty against defects for the warranty period shown below, subject to the product type, application and the terms of this warranty policy.
The express warranty provided by us is limited to a maximum of 5 years from the original date of purchase, unless otherwise required under Australian Consumer Law.
Blue Sea Systems may offer longer manufacturer support on some products at their discretion
Warranty Lengths by Product Range
| Blue Sea Product Range | Warranty Length | Application / Notes |
|---|---|---|
| Most Blue Sea Systems Products | 5 years | Applies to most Blue Sea Systems products found to be defective in materials or manufacture. |
| P12 Battery Chargers | 5 years | Warranty period starts from the original date of purchase. |
| P12 Remote Displays | 5 years | Warranty period starts from the original date of purchase. |
| Digital Meters | 3 years | Warranty period starts from the original date of purchase. |
| Vessel System Monitors | 3 years | Warranty period starts from the original date of purchase. |
Warranty Assessment and Remedy
If a Blue Sea Systems product is found to be defective in materials or manufacture within the applicable warranty period, we will, at our discretion, arrange a repair, replacement, store credit or refund, depending on the nature of the fault and the requirements of Australian Consumer Law.
Products may need to be returned for assessment before a warranty claim can be approved. Where required, the product must be returned with dated proof of purchase and a clear description of the fault.
Labour costs for removing, replacing, reinstalling or diagnosing a product are not covered by this express warranty unless otherwise required under Australian Consumer Law.
Making a Warranty Claim
To make a warranty claim, please contact us with your dated proof of purchase, product details and a description of the fault.
The product may need to be returned for inspection before the claim can be assessed. If the product is confirmed to be faulty and covered by this warranty, we will advise the available remedy.
What This Warranty Does Not Cover
This warranty does not cover faults or damage caused by incorrect installation, incorrect application, misuse, abuse, neglect, unauthorised modification, accidental damage, normal wear and tear, environmental damage, or failure to use the product in accordance with the manufacturer's instructions.
- Incorrect installation or wiring
- Incorrect product selection or application
- Misuse, abuse or neglect
- Physical or accidental damage
- Water ingress or environmental damage outside the product's intended use
- Unauthorised modification or repair
- Normal wear and tear
- Labour costs for removal, replacement, reinstallation or diagnosis
- Freight, travel or call-out costs unless otherwise required by law
- Products not returned for assessment when reasonably required
Manufacturer Support
Blue Sea Systems may provide additional manufacturer support on some products beyond the warranty period listed above. Where available, we may assist customers in contacting the manufacturer, but any manufacturer support beyond the express warranty period is subject to the manufacturer's own terms and continued availability.
Australian Consumer Law
This warranty is in addition to other rights and remedies available at law. Our goods come with guarantees that cannot be excluded under the Australian Consumer Law. You are entitled to a replacement or refund for a major failure and compensation for any other reasonably foreseeable loss or damage. You are also entitled to have the goods repaired or replaced if the goods fail to be of acceptable quality and the failure does not amount to a major failure.
