BMS Current Sensor Shunt 300A 50mV

Precision 300A Current Shunt for Battery Management Systems

Accurate Current Sensing for Reliable BMS Monitoring

The BMS Current Sensor Shunt 300A 50mV is a high-precision manganin shunt resistor engineered for battery management systems in off-grid, marine, and industrial applications. Designed to deliver a stable 50mV output at 300A, this shunt enables accurate current measurement for state-of-charge calculations, load monitoring, and system protection. Its robust construction and low resistance minimise power loss while maintaining signal integrity, making it a dependable choice for demanding DC power systems.

Unlike generic shunts that may drift or introduce excessive voltage drop, this unit uses a manganin sensing element with a rated accuracy of ±0.25% maximum. This ensures consistent readings across a wide temperature range, reducing the risk of BMS errors that could lead to overcharging or deep discharge. The brass terminal posts and 3/8"-16 (Approx. M10) studs provide secure connections for heavy-duty lugs up to 4/0 AWG (approx. 95mm²), supporting high-current pathways without hotspots.

Key Features

• 300A / 50mV output for direct compatibility with most BMS units and battery monitors
• Manganin resistive element with ±0.25% accuracy for stable, low-drift performance
• Low resistance of 0.000167 Ω reduces power dissipation and thermal drift
• Brass terminals with 3/8"-16 (Approx. M10) studs accept heavy-gauge lugs for secure, low-resistance connections
• 750V isolation rating enhances safety in high-voltage battery banks
• Wide operating temperature range from -40°C to +60°C for reliable operation in harsh environments
• Compact footprint (82.5mm x 44.4mm) with 5.08mm mounting holes for easy integration

Built for Critical DC Power Systems

This shunt is purpose-built for lithium battery systems, solar storage, and marine electrical panels where precise current data is essential. The manganin alloy minimises temperature-induced resistance changes, a common issue with lower-grade copper shunts, ensuring your BMS receives accurate data even during high-load events. The 750V isolation rating provides an additional safety margin when used in series-connected battery banks up to 48V nominal, protecting sensitive monitoring electronics from voltage transients.

Installation is straightforward with the pre-drilled mounting holes (5.08mm diameter) and standard 8-32 screw terminals for the sense wires. The 1.5" (38.1mm) stud centre spacing allows for neat cable routing in confined enclosures. *Note typical de-rating factors apply; ensure adequate ventilation and consider ambient temperature when operating near maximum continuous current.

Applications

• Battery management systems for lithium LiFePO4 and lead-acid banks
• Solar charge controller and inverter current monitoring
• Marine and RV electrical systems requiring accurate amp-hour tracking
• Industrial DC power supplies and load testing equipment
• Off-grid energy storage and backup power systems

Why Choose a Manganin Shunt?

Manganin is a copper-manganese-nickel alloy known for its extremely low temperature coefficient of resistance. This means the shunt maintains its calibrated accuracy even as internal temperatures rise under load, unlike brass or copper alternatives that can introduce measurement errors. For BMS applications where millivolt signals directly correlate to battery state-of-charge, this stability is critical for preventing premature charge termination or unexpected shutdowns.

With a torque range of 14-15 ft-lbs (19.0-20.3 Nm) on the main studs, you can achieve consistent clamping force without damaging the brass terminals, ensuring long-term connection reliability in high-vibration environments such as marine engine rooms or off-road vehicles.

Integrate Precision Current Sensing Today

Upgrade your battery monitoring setup with a shunt designed for accuracy and durability. Whether you're building a new lithium bank or retrofitting an existing system, the BMS Current Sensor Shunt 300A 50mV provides the reliable data your BMS needs to protect your investment. Add it to your system today and monitor with confidence.