MG Energy Systems
MG AFC300 Alternator Field Controller
£1,132.80
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MGAFC480300
An alternator field controller that regulates a standard alternator over NMEA2000 CAN-bus to charge MG lithium battery systems, with temperature, current and load dump protection.
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Available for collection or delivery in ~2 days
Pickup available at Mercury Yacht Harbour
Usually ready in 2-4 days
Description
The MG AFC 300 is an alternator field controller that lets a standard engine alternator charge an MG lithium-ion battery bank safely. By regulating the current in the alternator field winding it follows the charge setpoints sent by the connected MG BMS over the NMEA2000 CAN-bus, so the battery is always charged under optimal conditions. An integrated shunt continuously measures alternator current and temperature and reduces output before the alternator can overheat.
Built-in load dump protection clamps any voltage overshoot and stops charging immediately if a fuse fails or the BMS main safety contactor opens, protecting the alternator and connected electronics. The AFC 300 suits 12 V, 24 V and 48 V systems and works with any alternator that has external field control, automatically detecting the field type and polarity so no special cable harness is needed. Multiple units run in parallel, and Bluetooth allows quick setup and monitoring through the MG Connect app.
PRODUCT DETAILS
- Regulates a standard external-field alternator to charge MG lithium battery systems
- Handles up to 300 A charge current for 12 V, 24 V and 48 V systems
- Automatic field polarity detection drives both N-type and P-type alternators
- Integrated shunt regulates alternator current and temperature to prevent overheating
- Built-in load dump protection clamps voltage overshoot on emergency shutdown
- Isolated M12 CAN-Bus, NMEA2000 and DVCC compatible for direct BMS control
- Bluetooth configuration and monitoring with the MG Connect app
- Fully encapsulated electronics for harsh marine environments
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Key specifications
| Device type | Alternator field controller (regulator) |
| Battery system voltage | 12 V, 24 V and 48 V |
| Maximum charge current | 300 A continuous |
| Maximum field control current | 20 A |
| Communication | NMEA 2000 over M12 CAN-Bus |
| Configuration | Bluetooth (MG Connect app) |
| IP protection class | IP22 |
Electrical
| Supply voltage range | 8 to 60 Vdc |
| Maximum current consumption | 21 A |
| Power consumption (standby, without field drive) | 1.2 W |
| Maximum charge current (continuous) | 300 A |
| Maximum field control current | 20 A |
| Ignition/enable input | 0 to 60 V, 7 V or higher is active |
| Programmable input | 0 to 60 V, 7 V or higher is active |
| Programmable output | Equal to field supply +, 0.5 A, short-circuit and overcurrent protection |
| W/Tacho input | 0 to 58 Vpp |
Communication
| Protocol | NMEA 2000 |
| Data connection | CAN-Bus M12 |
| Bluetooth | Yes, for configuration via MG Connect app, can be disabled by hardware switch |
Mechanical
| Dimensions (L x W x H) | 255 x 132 x 63 mm |
| Weight | 1.5 kg |
| Enclosure material | PC ABS / ABS (reinforced) |
| Mounting feet | 4x max 6.5 mm diameter |
| IP protection class | IP22 |
| Operating temperature range | -20 to +50 degrees C |
| Humidity | 95% maximum, non-condensing |
General
| Field polarity detection | Automatic, N-type and P-type alternators |
| Load dump protection | Integrated |
| Manufacturer | MG Energy Systems |
| Country of origin | Netherlands |
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Which MG battery systems and BMS units is the AFC 300 compatible with?
The AFC 300 communicates over an isolated M12 CAN-Bus using the NMEA2000 protocol and works with MG battery systems only, including the MG Master LV, MG SmartLink MX and MG SmartLink Connect. It follows the charge setpoints from the connected BMS so the alternator charges the lithium bank under optimal conditions.
What types of alternator can the AFC 300 control?
It supports 12 V, 24 V and 48 V battery systems and any alternator with external field control where one or both field wires are accessible. Automatic field polarity detection drives both N-type and P-type alternators, and the unit senses the connected field type automatically so no different cable harnesses are required.
How does the AFC 300 protect the alternator against overheating and load dump?
An integrated shunt continuously monitors alternator current and temperature and regulates the field to prevent overtemperature. Built-in load dump protection clamps the voltage overshoot and stops charging immediately if a fuse breaks or the BMS main safety contactor opens.
