Sapphire Energy
MRBF Battery Fuse (2pk)
MRBF Battery Fuse (2pk)
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MRBF Marine Battery Fuses – 2-Pack
Protect your battery bank and DC electrical system with our marine-grade MRBF battery fuses. These compact, high-current fuses feature IP66 waterproof construction, ignition protection, and high interrupt capacity, making them ideal for marine, RV, automotive, and off-grid electrical installations.
Rated for up to 58V DC, MRBF (Marine Rated Battery Fuse) cartridges are designed for installation in compatible battery terminal fuse holders, allowing overcurrent protection to be positioned close to the battery or DC distribution point.
Each package includes two identical MRBF fuses in your selected amperage. Install both in a dual fuse holder, protect two separate circuits, or keep a spare ready for convenient replacement.
Why You'll Love It
- High Interrupt Capacity: Up to 10,000A interrupt rating at 14V DC for protection against high-current electrical faults.
- IP66 Waterproof Construction: Dust-tight and resistant to powerful water jets for demanding marine and mobile environments.
- Ignition Protected: Designed for safe operation in appropriate marine installations, including gasoline-powered vessels.
- 58V DC Rated: Suitable for compatible 12V, 24V, and higher-voltage DC battery systems.
- Compact Terminal-Mount Design: Provides effective circuit protection without requiring a bulky inline fuse block.
- Convenient 2-Pack: Two matching fuse cartridges for dual-circuit installations or keeping a spare on hand.
Need an MRBF Fuse Holder?
Fuse holders are sold separately. Pair these fuses with our corrosion-resistant tinned copper MRBF holders, available in Single and Double (Dual) configurations. Each holder includes stainless steel fastening hardware and a protective red silicone insulating cover.
Prefer everything together? Our complete MRBF Fuse Kits include your selected holder and two matching fuses.
High Interrupt Capacity for Battery Protection
Batteries can deliver extremely high currents during a short circuit, making the fuse's interrupt rating just as important as its amperage rating.
The amperage rating determines the current a fuse is designed to carry, while the interrupt rating indicates the maximum prospective short-circuit current the fuse can safely interrupt under specified conditions.
These MRBF fuses combine high interrupt capacity with a compact design, making them a practical solution for protecting battery cables and DC distribution circuits.
| Operating Voltage | Interrupt Capacity |
|---|---|
| 14V DC | 10,000A (10kA) |
| 32V DC | 5,000A (5kA) |
| 58V DC | 2,000A (2kA) |
Interrupt capacity decreases at higher operating voltages. Always select a fuse with sufficient interrupt capacity for the available short-circuit current of your battery bank.
IP66 Waterproof & Ignition-Protected Construction
Designed for demanding electrical environments, these MRBF fuses feature sealed ceramic construction with IP66 ingress protection. This provides complete protection against dust ingress and resistance to powerful water jets.
The fuses also feature ignition-protected construction conforming to SAE J1171, making them suitable for appropriate marine applications, including electrical installations aboard gasoline-powered vessels.
Their compact construction makes them particularly useful where space is limited, while the replaceable cartridge design allows straightforward servicing without replacing the entire fuse holder.
Applications
- Marine Battery Systems: Protection for onboard battery banks, DC distribution, and auxiliary electrical equipment.
- LiFePO₄ Battery Installations: Overcurrent protection where the fuse's voltage and interrupt ratings are suitable for the battery bank.
- RVs & Camper Vans: Compact protection for house batteries, auxiliary circuits, and mobile DC power systems.
- Off-Grid Solar Systems: Battery and DC distribution protection for cabins, tiny homes, and remote installations.
- Battery Busbars: Individual circuit protection using compatible single or double MRBF fuse holders.
- Parallel Battery Banks: Individual battery cable protection where required by the system design.
Technical Specifications
| Product Type | MRBF Marine Battery Fuse |
|---|---|
| Fuse Construction | Sealed Ceramic Cartridge |
| Quantity | 2 Fuses per Pack |
| Maximum Voltage | 58V DC |
| Interrupt Ratings @ 14V DC | 10,000A (14VDC) 5,000A (32VDC) 2,000A (58VDC) |
| Ingress Protection | IP66 |
| Ignition Protection | SAE J1171 |
| Dimensions | 23.0 x 27.8 x 16.3 mm 0.91" x 1.09" x 0.64" |
| Approximate Weight | 30 g per Fuse |
| Compatible Holder Type | Standard MRBF Fuse Holder |
What's Included
- 2 × IP66 MRBF Marine Battery Fuse Cartridges
Building a New Battery System?
Simplify your installation with a complete MRBF Battery Fuse Kit. Choose a Single or Double tinned copper holder and your preferred fuse amperage.
Every kit includes the selected holder, protective silicone insulating cover, stainless steel fastening hardware, and two matching MRBF fuses. With a Single holder, the second fuse serves as a spare. With a Double holder, both fuses can be installed to protect two separate circuits.
Frequently Asked Questions
Are these MRBF fuses compatible with Blue Sea Systems fuse holders?
Yes. These fuses use the standard MRBF cartridge configuration and are compatible with Blue Sea Systems MRBF fuse holders, as well as our own Single and Double MRBF holders.
Always select the appropriate fuse amperage for your wiring and equipment, and ensure the holder is suitable for the installation.
Can I install an MRBF fuse directly onto a battery terminal without a holder?
No. MRBF fuses must be installed using a compatible MRBF fuse holder. Installing a fuse directly onto a battery terminal allows the mounting bolt to create an electrical path that bypasses the fuse element entirely.
This renders the fuse ineffective because current can flow through the bolt instead of the fuse. During a short circuit, the fuse may not interrupt the current, leaving the connected wiring without the intended protection.
A proper MRBF holder features an electrically isolated terminal stud, ensuring current passes through the fuse element before reaching the connected cable.
What amperage MRBF fuse should I choose?
The appropriate fuse amperage depends on the connected equipment, cable size, installation conditions, and maximum expected operating current.
The fuse should be sized to protect the wiring against excessive current while accommodating normal equipment operation, including permissible startup or surge currents.
For lithium battery systems, also consider the battery's maximum discharge current, BMS specifications, and the battery bank's available short-circuit current.
Can I use MRBF fuses with 48V LiFePO₄ batteries?
MRBF fuses can be used in lithium battery systems when their voltage rating and interrupt capacity are suitable for the installation.
These fuses have a maximum voltage rating of 58V DC. Some nominal 48V LiFePO₄ battery systems can exceed this voltage during charging, so the maximum operating voltage of the complete system must be checked before selecting an MRBF fuse.
At 58V DC, these fuses have an interrupt rating of 2,000A. The battery bank's available short-circuit current must also remain within the applicable interrupt rating.
Higher-voltage or higher-fault-current installations may require a suitably rated alternative, such as a Class-T fuse.
What is the difference between fuse amperage and interrupt capacity?
Fuse amperage is the nominal current rating used when selecting protection for connected wiring and equipment.
Interrupt capacity is the maximum prospective short-circuit current the fuse can safely interrupt under specified conditions.
For example, a 100A MRBF fuse has a nominal current rating of 100A, but can safely interrupt substantially higher fault currents within its specified interrupt capacity.
Both ratings are important, particularly when protecting LiFePO₄ battery banks capable of delivering high short-circuit currents.
Are these MRBF fuses waterproof?
Yes. These MRBF fuse cartridges feature IP66-rated construction, providing dust-tight protection and resistance to powerful water jets.
Their sealed ceramic construction makes them suitable for demanding marine and mobile environments. However, IP66 does not mean the fuse is intended for continuous submersion.
Electrical connections should still be protected against moisture, contamination, and accidental contact. Our MRBF fuse holders include a flexible red silicone insulating cover for additional protection.
Are MRBF fuses ignition protected?
These MRBF fuses feature ignition-protected construction conforming to SAE J1171, making them suitable for appropriate marine electrical installations, including gasoline-powered vessels. Be aware that not all MRBF are ignition rated.
Ignition protection is particularly important in environments where flammable fuel vapours may be present. Always follow applicable marine electrical installation requirements when selecting and installing overcurrent protection.
Should each battery in a parallel battery bank have its own fuse?
Individual battery fusing is generally recommended for parallel battery installations, with each battery's positive connection protected by an appropriately rated fuse.
This helps protect individual battery cables against excessive fault current, including current supplied by other batteries connected to the same bank.
MRBF terminal-mounted fuses provide a compact solution because they can be installed close to each battery's positive terminal using a compatible holder.
Can I use two different fuse amperages in a Double MRBF holder?
Yes. A Double (Dual) MRBF fuse holder allows two independently fused circuits to share a common battery terminal or busbar connection.
Each fuse position can use a different amperage, provided the selected fuse is appropriate for its circuit.
When using different ratings, we recommend installing the smaller-rated fuse on the outermost (furthest) fuse position.
The combined current through the holder must not exceed its 300A total maximum rating.
Are fuse holders included with the MRBF 2-pack?
No. Each package contains two identical MRBF fuse cartridges in your selected amperage. Fuse holders are sold separately.
For a new installation, our complete MRBF Fuse Kits include your choice of Single or Double holder, a protective silicone insulating cover, and two matching MRBF fuses.
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