Blue Sea Systems m-Series Single Circuit ON-OFF Battery Switch, Locking Key, 48V DC, 300A Continuous, IP66, 3/8 in Studs
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Overview
The Blue Sea Systems m-Series Mini Battery Switch is a single-circuit ON-OFF battery switch with a locking key for controlling one battery feeding one load group on board. It is rated for 48V DC systems, with a 300A continuous rating, 500A intermittent rating, and 900A starting rating for 30 seconds, making it a practical fit for many outboard and small gasoline or diesel engine installations.
The switch uses tin-plated copper studs that accept 3/8" (M10) ring terminals, with a 7/8" (22 mm) stud length to help accommodate multiple cable terminals where the installation allows. An isolating rear cover protects the contacts, while breakout tabs let cables enter from different directions for cleaner routing in compact battery compartments, helm panels, or equipment lockers.
Key features
- Single Circuit ON-OFF switching for one battery connected to one load group.
- 300A continuous rating with 900A starting capacity for 30 seconds.
- Maximum voltage rating of 48V DC for common low-voltage marine electrical systems.
- Tin-plated copper studs help maintain conductivity and resist corrosion in damp marine spaces.
- 3/8" (M10) studs work with standard heavy-duty marine battery cable ring terminals.
- Locking key operation helps limit accidental or unauthorized switching.
- IP66 rating supports use in areas exposed to spray and washdown.
- Ignition protected and rated to ISO 8846, SAE J1171, UL 1107, and UL 1500.
Variants
This switch is offered in two color configurations. Both variants use the same single-circuit ON-OFF layout with a locking key, the same 48V DC maximum voltage rating, and the same current ratings.
The color change affects how the switch presents on the boat and how easily it matches nearby panels, battery labels, or existing Blue Sea Systems electrical hardware.
- 6004: Red. The red version gives the battery control point a traditional high-visibility look, which can help it stand out in a battery compartment or behind an access panel.
- 6004200: Black. The black version has a more subdued appearance for helm panels, equipment lockers, or installations where the switch needs to blend with surrounding hardware.
Installation and fit
The compact m-Series form factor works well where space is limited but the battery switch still needs to handle engine starting loads. The case supports surface, front panel, or rear panel mounting, so it can be fitted to a bulkhead, panel face, or protected enclosure depending on the layout of the boat.
Use properly sized marine battery cable and ring terminals for the load being carried. The 3/8" terminal studs should be torqued to 120 in-lb (13.56 Nm), and the rear cover should be positioned so the live contacts remain protected after installation.
Electrical and marine use
This is a manual battery isolation switch for straightforward ON-OFF control, not a battery combiner or selector switch. It is a good match for boats that need a clear way to disconnect one starting or house battery feed when leaving the vessel, working on the electrical system, or shutting down nonessential loads at the dock.
The IP66 rating, ignition protection, tin-plated copper studs, and stainless flange nuts make it suitable for the kind of damp, vibrating, and corrosion-prone spaces found on small powerboats, tenders, fishing boats, and compact cruising boats.
Shipping
We ship worldwide from the United States. Rates are calculated at checkout based on destination and package weight. Some items include free shipping, which will show automatically. Not every product is eligible for international shipping; checkout will confirm eligibility. We do not ship to PO Boxes except through USPS, and not all packages qualify.
Processing and dispatch
Most orders are verified, packed, and handed to the carrier within 1 to 2 business days. Some products may need extra handling time or ship directly from the manufacturer. For certain international orders, inventory transfers between warehouses may add time. If any delay is expected, we will let you know the dispatch date.
Delivery and tracking
Deliveries are handled by trusted carriers such as USPS, UPS, FedEx, and DHL. Estimated arrival times appear at checkout and depend on your location and the service you choose. These are estimates and can be affected by customs or carrier disruptions. A shipping confirmation with a tracking link is emailed when your order ships, and tracking may take up to 24 hours to update. You can also view tracking in your account.
Duties, taxes, and support
International customers are responsible for any customs duties, taxes, and fees charged by the destination country. If these charges are refused and a shipment returns to us, the carrier’s return cost and any re-entry customs fees will be deducted from the refund. If your order is late or you need help, contact cs@qualityboatparts.com and we will assist you.
Quality Boat Parts is a reseller. Many items include a manufacturer’s warranty, and all warranty service is handled directly by the manufacturer. We do not manage or administer warranty claims on behalf of customers.
Warranty terms, coverage, and duration are set by each manufacturer. Issues involving defects, repairs, or replacements must be addressed with the manufacturer’s support team. When available, the warranty period is listed on the product page. If it is not shown, contact us or the manufacturer for details before purchasing.
To start a claim, the customer must contact the manufacturer and follow their process. Keep your proof of purchase and original packaging, and register the product if the manufacturer requires it, as these are often needed for warranty service.
We are happy to help you find the right contact or documentation, but we cannot decide outcomes or intervene in claim resolutions. For guidance, email cs@qualityboatparts.com.