Get 10,000W of Charging Power With an Alternator Without Installing a Separate Generator
Your engine already produces the mechanical power you need. The Safiery 48V Bidirectional Motor Generator converts it into 11,000W of charging capacity—mounted directly to your existing alternator position, with no separate genset required.
Finally, an Alternator Replacement Built for Modern Lithium Battery Systems
If you’re running a large lithium battery bank on your boat, RV, or off-grid vehicle, you already know the frustration. Traditional alternators deliver a fraction of their rated output at idle. In a traditional alternator, the stationary stator contains three separate coil windings spaced 120 degrees apart; as the rotor spins inside, these coils generate AC (alternating current), which is then rectified to DC for the vehicle’s electrical system. Smart alternators improve slightly but still max out at 800W when your engine is barely ticking over. Meanwhile, your 48V lithium system sits waiting for meaningful charge current.
Most operators end up installing a separate diesel generator—adding weight, complexity, fuel consumption, and another engine to maintain. The Safiery 48V Bidirectional Motor Generator eliminates that requirement entirely.
The BMG mounts to the same position as your car alternator, connects to the same belt and pulley system, and uses the same mechanical power from your engine. The difference: it delivers 5,000W at engine idle and scales to 11,000W at cruising RPM. This is alternator output that matches or exceeds a dedicated genset—without adding a second engine to your electrical system.
Why the Safiery BMG Works Where Traditional Alternators Fail
Here’s what separates this technology from every other charging system on the market:
5,000W at engine idle – Hybrid excitation technology delivers full power at low rotational speed, where conventional field windings produce almost nothing
Bidirectional operation – Functions as both generator and starter motor, unlike any traditional alternator which can only convert mechanical power to electrical power in one direction
Real-time torque protection – Scotty AI monitors engine load continuously and reduces power instantly if your engine approaches its limits, helping protect the alternator and engine from overload, preventing stalling or excessive smoke
85% system efficiency – Compared to 50% from a conventional alternator running hot, this translates directly to reduced fuel consumption and lower thermal stress
Automotive-grade reliability – AEC Q101/Q200 certified components tested to withstand 1,500G mechanical shock, −65°C to +150°C temperature cycling, and 1,000+ hours of high-temperature operation
The BMG features advanced voltage regulation that maintains a constant output voltage by dynamically adjusting the excitation current. This ensures stable battery charging and protects sensitive electrical components from voltage fluctuations.
Instead of forcing you to choose between inadequate charging or installing a separate genset, the BMG gives you genset-level power from your existing propulsion engine.
How the BMG Installation Process Works
Getting maximum charging power doesn’t require engine modifications or custom fabrication. The process is straightforward.
Step 1: Direct Bolt-On Mounting
The BMG mounts to your existing alternator position using factory mounting points. Whether you’re running a Yanmar marine diesel, Volvo Penta D-series, Cummins commercial engine, or Mercedes-Benz Sprinter, Safiery has developed specific mount configurations that bolt directly to the engine. No cutting, welding, or custom bracketry required.
The belt connects to your existing crankshaft pulley, and the over-running auto-clutch pulley (standard on marine models) protects both the BMG and drive system from reverse shock loads during start-up and load transitions.
Step 2: Scotty AI V3 Integration
Connect the Scotty AI V3 controller via CAN (Controller Area Network) for complete digital control of the charging system. The Scotty AI integrates directly with Victron energy systems—appearing as an alternator device on your Cerbo GX or Ekrano GX display (firmware v3.63 or later required).
Two independent CAN ports allow simultaneous connection to your BMG and your Victron VE.CAN network or CAN BMS. Every charging parameter—bulk voltage, absorption time, float voltage—is configured through the Scotty AI app and stored as failsafe values.
Step 3: Immediate High-Power Charging
From your first engine start, the BMG begins delivering power. At idle, expect 5,000W+ when paired with a 12V alternator and Scotty AI power arbitrage. At cruising RPM, output scales to 8,000W continuous, with peak capacity reaching 11,000W.
No break-in period. No gradual power increase. Your battery bank receives meaningful charge current from the moment the engine runs.
What Makes the BMG Different from Every Other Alternator
Most alternator upgrades focus on incremental improvements—slightly more output, marginally better voltage regulation, somewhat improved cooling. The BMG operates on fundamentally different principles.
Dual three-phase hairpin stator windings – Two independent winding sets shifted 30° electrical create 12-pulse rectification, reducing output ripple by 75% compared to conventional single-phase alternators and providing redundancy if one winding experiences a fault. The stator windings are made up of coils of wire, and as the rotor spins inside, voltage is induced in these coils according to Faraday’s law of electromagnetic induction.
Hybrid excitation technology – Permanent magnets provide strong baseline magnetic field at any RPM, while controlled field windings modulate voltage and torque precisely—enabling full power at idle where conventional alternators produce almost nothing. The voltage regulator ensures that the correct voltage is fed to the rotor electromagnet to maintain consistent output.
Space Vector PWM control – The same digital inverter control algorithm used in premium EV traction motors and industrial servo drives, delivering 15.47% higher DC bus utilisation than sinusoidal PWM and enabling precise torque control unavailable with simple diode bridge rectification.
100% digital CAN control – Zero analogue drift over temperature and time, instant response to changing conditions, and full bidirectional telemetry—compared to analog field current regulation used by every other smart alternator regulator.
Four-point temperature monitoring – Motor temperature, inverter temperature, and additional thermal points continuously monitored with graduated derating starting at 120°C—versus the single thermistor systems in conventional alternators that provide minimal visibility into internal conditions.
In conventional alternators, the rectifier consists of several diodes that convert the alternating current (AC) produced by the stator into direct current (DC). A diode trio converts part of the stator output to DC, which is then fed to energize the rotor electromagnet once the engine is running. The alternator produces electrical current using the laws of induction and magnetism, with its rotor spinning inside a stator to generate voltage.
If conventional alternators offer compromise, the BMG offers capability that didn’t exist in this form factor until now.
Technical Performance Data
The numbers that matter for operators making charging system decisions:
Operating Condition | Safiery BMG + Scotty AI V3 | Best-in-Class Smart Alternator |
|---|---|---|
At engine idle | 5,000W | 200–800W |
At 1,800 RPM (cruising) | 8,000W | 5,000–6,000W |
Peak output | 11,000W | 6,000–7,400W |
Efficiency at operating temp | 85% (net) | ~50% when hot |
Inverter type | AEC Q-certified digital inverter | Diode bridge |
Temperature monitoring | 4-point | 1-point |
Torque protection | Yes—real-time AI | No |
Load dump protection | 100% guaranteed | Not available |
Bidirectional capability | Yes | No |
The efficiency difference compounds over every charging hour. A conventional alternator running hot wastes half of every watt of mechanical power as heat. The BMG’s 90% motor efficiency and 94% inverter efficiency combine for 85% net system efficiency—directly translating to lower fuel consumption and reduced engine thermal stress.
Technical specifications:
Motor type: Claw-pole, dual 3-phase hairpin with rotating magnetic field
Motor diameter: 150mm | Length: 155mm (without shaft and pulley)
Weight: 7.3kg (without OAP)
Nominal operating voltage: 40V–57.9V | Maximum: 60V
Peak output: 10kW @ >5,000 RPM (20 seconds)
Continuous output: 5kW @ >6,000 RPM
Maximum speed: 16,000 RPM
Voltage accuracy: ±0.5V (vs ±2% for conventional alternators)
Operating temperature: −30°C to 105°C
Response time: 150ms without pre-flux
Automotive alternators typically output between 50 to 70 amperes, while larger alternator models for trucks or specialty vehicles can produce up to 300 amperes. The voltage regulator, which may vary in appearance depending on the alternator model, plays a key role in regulating battery and stator voltage for optimal performance.
The BMG is engineered to suit a wide range of vehicles and alternator models, ensuring compatibility and flexibility for both standard and high-demand applications.
The cost to replace an alternator generally ranges from $585 to $850 or more, depending on the alternator model and installation complexity. Replacing a faulty alternator is crucial for vehicle safety and reliability, as a failed alternator can cause the vehicle to stop running unexpectedly and may pose a safety risk.
Who the BMG Is Designed For
The Safiery BMG serves operators who need maximum charging capacity without the complexity of separate generation equipment:
Marine operators running Yanmar or Volvo Penta engines with large lithium banks who need to fully charge during a normal passage without running the engine for hours at elevated RPM
Commercial vehicle operators with Cummins or Caterpillar power requiring high-capacity charging for auxiliary equipment, refrigeration, or mobile workshops
Mercedes Sprinter overlanders who want genset-level power generation without the weight, noise, and maintenance of a separate generator
Off-grid and RV enthusiasts who currently operate solar plus alternator charging but find their conventional alternator chargers can’t sustain high loads at idle without overheating or dropping output
If you need your existing engine to generate the electrical power of a dedicated genset—while maintaining full engine protection and integration with modern energy management systems—the BMG was built for your application.
BMG Models and Configurations
SHSA4803 – Yanmar Marine Engines
Introduction to Sustainable Boating
SHSA4803 – Yanmar Marine Engines
The SHSA4803 uses the J180 mount standard for direct installation on Yanmar marine diesel engines. This configuration dominates the global sailing, motoryacht, and commercial vessel markets where Yanmar power is standard.
J-180 mount compatibility for Yanmar marine diesels
Over-running auto-clutch pulley (OAP) standard—protects the belt and drive system from shock loads during the bidirectional torque reversals that occur when transitioning between motor and generator modes
Ideal for liveaboard sailing and passage-making applications
For a 30hp or 40hp Yanmar at idle, the BMG delivers 5,000W into the 48V bank. At cruising RPM, output rises to 8,000W+. A 400Ah 48V lithium bank can receive a meaningful charge—potentially flat to full—during a normal coastal passage engine run.
SHSA4804 – Volvo Penta Marine Engines
The SHSA4804 is engineered for Volvo Penta marine diesel engines across the D2 through D11 range—from the compact D2-40 in 35–40ft production sailboats to the D11 inline-six in serious powerboats and commercial vessels.
Compatible with D2 through D11 range engines
Factory-position mount for clean OEM-style installation
Proper belt alignment geometry for long-term marine reliability
Available from mid-2025
For shipyards and refit yards working with Volvo power, this mount enables BMG installation without custom bracketry.
SHSA4801 – Cummins and Caterpillar Engines
The SHSA4801 Pad Mount serves operators running Cummins, Caterpillar, John Deere, or other heavy-duty commercial diesel engines. This is Safiery’s highest-output variant.
SAE standard pad mount for heavy-duty diesels
Continuous 300A peak at 48V—up to 15kW peak output power
Compatible with Cummins QSB, QSC, QSL, QSM series; Caterpillar C-series marine and industrial engines
Full bidirectional capability—motor mode available for auxiliary engine starting, torque assist, and regenerative energy capture
For workboats, commercial fishing vessels, offshore support, and heavy transport running Cummins or Caterpillar power, the SHSA4801 delivers alternator performance previously only available through dedicated stand-alone generator sets.
SHSA4802 – Mercedes-Benz Sprinter
The SHSA4802 serves the rapidly growing Sprinter-based overland and commercial vehicle market.
Compatible with N62 kit, 2025 model 4-cylinder, and prior-year 6-cylinder configurations
Genuine Mercedes-Benz mounting kits for OEM-quality installation to factory-supplied second alternator position
Over-running auto-clutch pulley standard
Perfect for overland builds requiring maximum off-grid power generation
Frequently Asked Questions
How much power can I get at engine idle?
With the Scotty AI V3 controller and a 12V alternator connected in parallel, the system delivers 5,000W at engine idle through continuous power arbitrage between sources. This is 6–25x more than the 200–800W available from the best smart alternators at the same engine speed.
Will this work with my Victron system?
Yes. The BMG integrates natively with Victron energy systems. The Scotty AI V3 appears as an alternator device on your Cerbo GX or Ekrano GX display (firmware v3.63 or later). Two BMG units connected as Master and Slave can show combined outputs exceeding 17kW on the GX display.
For Victron Lithium battery users: charge current limit and discharge current limit parameters are not passed via NMEA2000, so configure your battery as a non-CAN battery in the Victron system while maintaining VE.CAN bus connection. Charging algorithms operate identically in CAN or non-CAN mode.
What about engine protection?
The Scotty AI reads engine torque from the BMG in real-time and reduces load instantly if the engine approaches overload. For small marine engines (30–40hp), a conventional smart alternator drawing maximum field current can stall the engine or cause excessive black smoke. Scotty AI prevents this entirely—not by limiting power to a conservative fixed level, but by continuously tracking actual available torque and modulating power dynamically.
Load dump protection is guaranteed. When a battery BMS opens its relay under charge and disconnects the alternator instantly, conventional systems can generate voltage spikes of 60–80V or more. Scotty AI guarantees 100% prevention of load dump damage—the digital inverter reduces output to zero in microseconds, regardless of whether the BMS stop-charge signal arrives slowly or fails entirely.
How does efficiency compare to my current alternator?
Conventional alternators operate at approximately 50% efficiency when hot—half of every watt of mechanical power drawn from your engine is converted to waste heat in the iron core, copper resistance, diode bridge losses, and cooling fan drag.
The BMG achieves 90% motor efficiency and 94% inverter efficiency for 85% net system efficiency at operating temperature. For operators charging large lithium banks for hours daily, this difference compounds into significant fuel savings and substantially reduced thermal stress on the engine.
What about slip rings and brushes?
The BMG’s hybrid excitation design uses permanent magnets as the primary flux source with controlled field windings for modulation. This reduces reliance on slip rings compared to conventional wound-field alternators where all excitation current must flow through the brushes. Combined with automotive-grade components tested to 1,000+ hours at maximum temperature, expected service life exceeds conventional alternator designs significantly.
Get Started With the Most Advanced Alternator Technology
The Safiery BMG represents a new category of alternator technology—designed from first principles for modern 48V lithium battery systems, high-power DC loads, and intelligent energy management networks.
This is not an incremental improvement over existing alternator models. It is a complete reconceptualization of what a belt-driven charging device connected to your engine can deliver: 11,000W peak output, 5,000W at idle, 85% efficiency, real-time engine protection, bidirectional operation, and seamless integration with the systems you’re already running.
Designed and manufactured in Australia. Automotive-grade reliability testing. Global delivery.
[Contact Safiery for Technical Consultation and Compatibility Verification →]
Verify your engine compatibility, discuss your specific power requirements, and receive detailed installation guidance from engineers who designed the system.
No long-term commitment. No pressure. Just answers about whether the BMG suits your application.