Engine
Engine 19HP — Volvo Penta MD2020 wiring diagram
Volvo Penta MD2020 family; the MD2020B manual specifies a 0.7 kW starter and 60 A alternator on 12 V. Modeled 110 A cranking and 220 A surge are estimates. Preserve the isolated flywheel casing/drive and separate 15 A control-circuit protection.
- Continuous draw
- 110 A
- Rated output
- 60 A
- Surge current
- 220 A
Wiring diagram
How the MD2020 19HP 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
- 110 A
- Voltage drop
- 0.8%
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. 7736669-8 English \u2014 February 1995), checked 2026-10-01. Exact variant details still require confirmation. Manufacturer documentation →
Engine and edition
The downloaded Volvo operator manual explicitly covers MD2020B, alongside MD2010B and MD2040B. Its electrical table specifies 12 V, a 70 Ah starter battery, 14 V/60 A alternator and approximately 0.7 kW starter output for MD2020B. The unsuffixed catalog name does not identify every later or earlier revision; match the engine plate before applying this harness drawing.
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
The engine wiring diagram shows the battery feed at starter terminal 30, a separate terminal 50 start-control connection, start and glow relays, three glow plugs, alternator B+/D+/W connections and a 16-pole panel connector. One 15 A fuse protects the positive control supply; the other three fuse positions are spares. That 15 A value is not a starter-feed fuse rating. Investigate an overload before moving the control wire to another fuse contact.
Checks and model limits
Volvo warns that the flywheel casing and transmission/saildrive are electrically isolated from the engine and must not be grounded. The Block GND symbol represents the intended engine return, not a bonding instruction for those isolated parts. Keep the battery connected while the alternator operates. The catalog 110 A cranking and 220 A surge remain estimates, not ratings stated by this manual. The drawing omits the panel, glow and alarm circuits and cannot establish that a lithium battery or battery switch is suitable for starting.
Source: manufacturer document — electrical isolation/fuses printed/PDF p. 23, engine wiring p. 27, electrical ratings p. 29. 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 MD2020 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.
Enable JavaScript to describe your system.
Technical reference
Specifications and terminal map.
Check the model, ratings and connection points against your own unit before choosing installation hardware.
Catalog specification
Volvo Penta MD2020 family; the MD2020B manual specifies a 0.7 kW starter and 60 A alternator on 12 V. Modeled 110 A cranking and 220 A surge are estimates. Preserve the isolated flywheel casing/drive and separate 15 A control-circuit protection.
- Continuous draw
- 110 A
- Rated output
- 60 A
- Surge current
- 220 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 MD2020 19HP.
Open this example as a new project, or add this component to your existing diagram. Use your equipment and cable lengths to review the sizing.
Start drawing, sizing and checking without an account. Your drawing saves in this browser. See Pricing for the equipment allowance and the one-time export offer available to you.