Beta 30
Engine — Beta Marine 30 wiring diagram
Beta Marine Beta 30 with a modeled 70 A charging configuration. The current manual documents several alternator and return arrangements, so confirm the fitted equipment. The 140 A cranking and 280 A surge are planning estimates, not manufacturer starter-current ratings.
- Continuous draw
- 140 A
- Rated output
- 70 A
- Surge current
- 280 A
Wiring diagram
How the Beta 30 is wired.
Open this example in Crimp to use your own parts and cable lengths. Review the assumptions and installation notes as you adapt the circuit.
Cable sizing for this example
Use the diagram as a starting point for your installation. Replace the example equipment and cable lengths with your own, and check the connections against your exact model's instructions.
3 m one way
12 V system
- Wire
- 120 mm² · 4/0 AWG
- Example fuse
- 250 A
- Cranking current
- 140 A
- Voltage drop
- 1.0%
Sized against ABYC E-11. The cranking current is what the starter draws. ABYC E-11 doesn't require a fuse on a cranking-motor conductor, so the fuse shown is the usual cranking-rated (Class T) choice, sized to hold the crank without nuisance tripping — it isn't there to protect the wire. The length is one way; voltage drop includes an equal-length return.
Run-length and manufacturer assumptions
The editable example uses 3.048 m (10 ft) runs unless a shorter run is stated. Metric overviews round these to 3 m. Adapt the parts and lengths to your installation before choosing cable and protection.
Supporting parts
- 6.1 m total of 120 mm² (4/0 AWG) marine cable
- Terminations for 120 mm² cable, matched to the equipment's screw terminals, leads or studs
- 250 A cranking-rated (Class T) fuse at the battery
- Heat-shrink, strain relief and terminal boots sized to the cable
Check stud sizes, fuse type, run length and how warm the space gets against the gear you actually have before you order.
Installation notes
Before you install.
Open a question for model-specific guidance and sources.
Reviewed against manufacturer family documentation (rev. OM 221-20031 REV 46 \u2014 0226), checked 2026-10-01. Exact variant details still require confirmation. Manufacturer documentation →
Engine and edition
Beta 30 is a three-cylinder Kubota-based engine, but electrical packages vary. The current manual lists a BD1105, 1123 cc engine and 30 hp EU maximum rating. Its Beta 30 specification table lists a 40 A standard alternator, while its B30–B45T wiring chapter also documents a 70 A configuration. The catalog 70 A is therefore a configuration assumption, not a universal production specification.
What the terminals mean
`Starter` represents the high-current starter supply, `Alt B+` the alternator charging output, and `Block GND` the intended negative return on an earth-return installation. They are functional drawing ports, not three interchangeable physical studs. Trace any factory link between alternator B+ and the starter battery stud before changing it; do not duplicate or remove that link without accounting for the original harness.
Controls and protection
For the documented 70 A installation, drawing 200-05452 shows the battery cable at the starter, alternator B+, a 40 A harness blade fuse, glow plugs, S5 stop solenoid and separate oil/coolant switch and sender connections. The fuse is in the harness branch, not in the starter motor feed. Select the drawing that matches the actual alternator and control panel.
Checks and model limits
The electrical troubleshooting chapter distinguishes standard earth-return engines from insulated-return versions, which require different harnesses, alternators and switches. Do not bridge an insulated installation to the block simply because this drawing has Block GND. The manual directs owners of pre-July-2005 engines to obtain the appropriate earlier guide. The catalog 140 A cranking and 280 A surge are estimates; neither the old 27.5 hp description nor an assumed starter wattage proves those currents.
Source: manufacturer document — Beta 30 specifications printed p. 10 (PDF 12), configuration guidance p. 68 (PDF 70), 70 A schematic p. 78 (PDF 80). Legacy copies hosted outside the manufacturer site are manufacturer-authored archive documents; the review date does not make them current installation instructions.
Fit check
Connect it to the rest of your system.
Describe your setup to draft a system with Beta 30 connected. Review the selected parts and cable lengths, then edit the diagram in Crimp.
The model only picks parts and draws the connections. Every wire size and fuse rating still comes from Crimp's own sizing, never from the model.
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Technical reference
Specifications and terminal map.
Check the model, ratings and connection points against your own unit before choosing installation hardware.
Catalog specification
Beta Marine Beta 30 with a modeled 70 A charging configuration. The current manual documents several alternator and return arrangements, so confirm the fitted equipment. The 140 A cranking and 280 A surge are planning estimates, not manufacturer starter-current ratings.
- Continuous draw
- 140 A
- Rated output
- 70 A
- Surge current
- 280 A
Terminal map
Catalog connection points, current direction and planning limits. Check the manufacturer's pinout and connector ratings before installation.
Starter
positive · input
Alt B+
positive · output
Block GND
ground · bidi
Sources and sizing method
Equipment specifications. Model details, ratings and terminal roles come from the catalog. Check your unit’s label and current manufacturer documentation for its exact revision.
Example sizing. Sized against ABYC E-11. Boats built to UK or EU rules answer to ISO 13297 — check these figures against it before you build. Results use the example current and run length shown above. Set your actual equipment, lengths and installation conditions in Crimp before choosing hardware.
Read how the sizing worksNext step
Plan your installation with Beta 30.
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