Editable DC examples
12 V boat wiring diagrams
Explore a boat’s 12 V system: engine, starter and house batteries, DC-DC charging, a SmartShunt, bilge pump and navigation lights. Start with the core circuits or open the full demo with solar charging, cabin appliances and stern lighting.
Boat engine, starter and house banks
14 components · 20 conductors · 12 V boat system
Live Crimp simulation. Try equipment states and battery charge, or choose Wiring to inspect the circuit. Cable IDs match the table below.
View full screenRed = positive · dark = return. Crossings are not junctions. Read the assumptions before adapting a circuit.
Protection is unfinished. The demo retains its battery-post fuses and cable fuse choices. These do not verify the complete protection or charging design; review the engine findings below and the actual installation. All charging and load currents below are design allowances, not measured operating currents.
Current engine findings
The fuse interrupt check uses the engine’s chemistry-based fault-current assumption. This is not measured fault current. Resolve the bank and protection design before installation.
Check the exact fuse, holder and battery evidence →- warning: Orion 18A has no return-path connection (system)
- warning: No MRBF fuse is made at 25 A (C15)
Cable table — every displayed connection
Each length is one way. Drop is the engine’s run estimate including return, not a measured end-to-end system result; shared legs can have different conservative design-current bounds. “Pinned” marks a saved demo choice to review after edits. AWG is approximate; retain the stated conductor area when selecting actual wire.
| Circuit / endpoints | One-way length | Conductor | Design current | Fuse | Drop / allowance |
|---|---|---|---|---|---|
| C1 · Negative Bus Bar 1 − ↔ Lanterns (LED) − | One-way length5 m16.4 ft | Conductor1.5 mm²AWG 16 · 25 A table | Design current0.5 A | Drop / allowance0.23% / 3% | |
| C2 · Main Battery Switch B ↔ Positive Bus Bar + | One-way length2 m6.6 ft | Conductor4 mm²AWG 11 · 45 A table | Design current6 A | FuseNo cable fuse set | Drop / allowance0.41% / 3% |
| C3 · Victron Orion-Tr Smart 12/12-18 IN − ↔ Junction | One-way length50 cm1.6 ft | Conductor1.5 mm²AWG 16 · 25 A table | Design current0 A | Drop / allowance0.00% / 3% | |
| C4 · Victron Orion-Tr Smart 12/12-18 OUT − ↔ Junction | One-way length50 cm1.6 ft | Conductor1.5 mm²AWG 16 · 25 A table | Design current18 A | Drop / allowance1.75% / 3% | |
| C5 · Positive Bus Bar 2 + ↔ Main Battery Switch A | One-way length50 cm1.6 ft | Conductor4 mm²AWG 11 · 45 A table | Design current6 A | FuseNo cable fuse set | Drop / allowance0.10% / 3% |
| C6 · Bilge Pump 1100 GPH + ↔ Positive Bus Bar 1 + | One-way length1 m3.3 ft | Conductor1.5 mm²AWG 16 · 25 A tablePinned choice | Design current3.5 A | Fuse7.5 A | Drop / allowance0.32% / 3% |
| C7 · Negative Bus Bar 1 − ↔ Bilge Pump 1100 GPH − | One-way length1 m3.3 ft | Conductor1.5 mm²AWG 16 · 25 A table | Design current3.5 A | Drop / allowance0.32% / 3% | |
| C8 · Negative Bus Bar 2 − ↔ Negative Bus Bar − | One-way length2 m6.6 ft | Conductor2.5 mm²AWG 13 · 35 A table | Design current6 A | Drop / allowance0.66% / 3% | |
| C9 · Engine 36HP — Volvo Penta MD17C Block GND − ↔ 80 Ah Start Battery − | One-way length1.5 m4.9 ft | Conductor70 mm²AWG 2/0 · 330 A table | Design current150 A | Drop / allowance0.88% / 3% | |
| C10 · 80 Ah Start Battery − ↔ Victron SmartShunt 500A LOAD − | One-way length50 cm1.6 ft | Conductor2.5 mm²AWG 13 · 35 A table | Design current9.5 A | Drop / allowance0.26% / 3% | |
| C11 · USB-C PD Outlet (60W) + ↔ Positive Bus Bar 2 + | One-way length50 cm1.6 ft | Conductor1.5 mm²AWG 16 · 25 A tablePinned choice | Design current5.5 A | Fuse7.5 A | Drop / allowance0.25% / 3% |
| C12 · 80 Ah Start Battery + ↔ Engine 36HP — Volvo Penta MD17C Starter + | One-way length1.5 m4.9 ft | Conductor70 mm²AWG 2/0 · 330 A table | Design current150 A | FuseNo cable fuse set | Drop / allowance0.94% / 3% |
| C13 · Victron SmartShunt 500A LOAD − ↔ Negative Bus Bar − | One-way length50 cm1.6 ft | Conductor2.5 mm²AWG 13 · 35 A table | Design current9.5 A | Drop / allowance0.26% / 3% | |
| C14 · Victron SmartShunt 500A B+ sense ↔ Positive Bus Bar + | One-way length50 cm1.6 ft | Conductor1.5 mm²AWG 16 · 25 A tablePinned choice | Design current0 A | Fuse2 A | Drop / allowance0.00% / 3% |
| C15 · Victron Orion-Tr Smart 12/12-18 OUT + ↔ 100 Ah LiFePO4 + | One-way length50 cm1.6 ft | Conductor1.5 mm²AWG 16 · 25 A tablePinned choice | Design current18 A | Fuse25 A | Drop / allowance1.64% / 3% |
| C16 · 100 Ah LiFePO4 − ↔ Victron SmartShunt 500A BATT − | One-way length50 cm1.6 ft | Conductor1.5 mm²AWG 16 · 25 A table | Design current9.5 A | Drop / allowance0.87% / 3% | |
| C17 · Lanterns (LED) + ↔ Positive Bus Bar 1 + | One-way length5.5 m18 ft | Conductor1.5 mm²AWG 16 · 25 A tablePinned choice | Design current0.5 A | Fuse1 A | Drop / allowance0.25% / 3% |
| C18 · Positive Bus Bar + ↔ 100 Ah LiFePO4 + | One-way length1 m3.3 ft | Conductor10 mm²AWG 8 · 80 A table | Design current9.5 A | FuseNo cable fuse set | Drop / allowance0.13% / 3% |
| C19 · Engine 36HP — Volvo Penta MD17C Alt B+ ↔ Victron Orion-Tr Smart 12/12-18 IN + | One-way length1 m3.3 ft | Conductor6 mm²AWG 10 · 60 A tablePinned choice | Design current40 A | Fuse50 A | Drop / allowance1.94% / 3% |
| C20 · USB-C PD Outlet (60W) − ↔ Negative Bus Bar 2 − | One-way length1 m3.3 ft | Conductor1.5 mm²AWG 16 · 25 A table | Design current5.5 A | Drop / allowance0.50% / 3% |
Component table and exact example assumptions
| Component | Ratings, role and assumptions |
|---|---|
| 80 Ah Start BatteryPlanning placeholder | 12 V · 80 Ah Cranking battery for diesel/petrol engine. |
| Main Battery SwitchPlanning placeholder | Single-pole disconnect on positive bus. |
| JunctionPlanning placeholder | A wire splice — any number of cables can meet here. Born from a cable dropped into empty space; promotes to a real junction once a second cable lands on it. |
| Bilge Pump 1100 GPHPlanning placeholder | 3.5 A load allowance Auto float-switch bilge pump, ~3.5A while running. |
| Positive Bus BarPlanning placeholder | Positive bus bar — common feed with multiple output studs. |
| Lanterns (LED)Planning placeholder | 0.5 A load allowance · 6 W Modern LED navigation lights — port, starboard, stern and masthead. Low draw, suitable for night passages. |
| Negative Bus BarPlanning placeholder | Negative bus bar — common return with multiple output studs. |
| Engine 36HP — Volvo Penta MD17CMD17C | 150 A load allowance · 55 A rated / planning output Volvo Penta MD17C — 36 HP / 26.5 kW @ 2400 RPM, 3-cyl. 1.4 kW starter cranks at ~150 A (~300 A inrush); alternators range from 35 to 55 A, with higher-output retrofits common. Very common in 30–35 ft Swedish cruisers (Hallberg-Rassy, Najad, Maxi). |
| Victron Orion-Tr Smart 12/12-18Orion-Tr Smart 12/12-18 | 18 A rated / planning output Isolated 18A DC-DC charger from start to house battery. Detects engine run from the input voltage and charges with a three-stage algorithm, set up over Bluetooth. |
| Negative Bus BarPlanning placeholder | Negative bus bar — common return with multiple output studs. |
| Positive Bus BarPlanning placeholder | Positive bus bar — common feed with multiple output studs. |
| Victron SmartShunt 500ASmartShunt 500A/50mV (IP21) | 500 A/50 mV battery shunt with Bluetooth and a VE.Direct port, no display. Reads out through the VictronConnect app or a GX device; the aux input can monitor a second battery, midpoint or temperature. |
| USB-C PD Outlet (60W)Planning placeholder | 5.5 A load allowance · 60 W |
| 100 Ah LiFePO4Planning placeholder | 12.8 V · 100 Ah Generic 12V 100Ah lithium iron phosphate house battery. |
Full boat demo — solar, cabin and stern
33 components · 53 conductors · 12 V boat system
Live Crimp simulation. Try equipment states and battery charge, or choose Wiring to inspect the circuit. Cable IDs match the table below.
View full screenRed = positive · dark = return. Crossings are not junctions. Read the assumptions before adapting a circuit.
Protection is unfinished. The demo retains its battery-post fuses and cable fuse choices. These do not verify the complete protection or charging design; review the engine findings below and the actual installation. All charging and load currents below are design allowances, not measured operating currents.
Current engine findings
The fuse interrupt check uses the engine’s chemistry-based fault-current assumption. This is not measured fault current. Resolve the bank and protection design before installation.
Check the exact fuse, holder and battery evidence →- critical: SmartShunt 500: B+ sense is a sense lead, not a bus (C31, C50)
- warning: MPPT 100/30 has no return-path connection (system)
- warning: Orion 18A has no return-path connection (system)
- warning: No MRBF fuse is made at 25 A (C32)
Cable table — every displayed connection
Each length is one way. Drop is the engine’s run estimate including return, not a measured end-to-end system result; shared legs can have different conservative design-current bounds. “Pinned” marks a saved demo choice to review after edits. AWG is approximate; retain the stated conductor area when selecting actual wire.
| Circuit / endpoints | One-way length | Conductor | Design current | Fuse | Drop / allowance |
|---|---|---|---|---|---|
| C1 · Flexible 100 W Panel + ↔ Junction | One-way length50 cm1.6 ft | Conductor1.5 mm²AWG 16 · 25 A table | Design current5.6 A | FuseNo cable fuse set | Drop / allowance0.36% / 3% |
| C2 · Junction ↔ Victron MPPT 100/30 PV + | One-way length4 m13.1 ft | Conductor4 mm²AWG 11 · 45 A table | Design current14.1 A | FuseNo cable fuse set | Drop / allowance2.74% / 3% |
| C3 · Victron MPPT 100/30 BATT − ↔ Junction | One-way length30 cm1.0 ft | Conductor4 mm²AWG 11 · 45 A table | Design current30 A | Drop / allowance0.66% / 3% | |
| C4 · Junction ↔ Victron MPPT 100/30 PV − | One-way length4 m13.1 ft | Conductor4 mm²AWG 11 · 45 A table | Design current14.1 A | Drop / allowance2.74% / 3% | |
| C5 · 200 W Solar Panel − ↔ Junction | One-way length50 cm1.6 ft | Conductor1.5 mm²AWG 16 · 25 A table | Design current8.5 A | Drop / allowance0.55% / 3% | |
| C6 · Negative Bus Bar 1 − ↔ Lanterns (LED) − | One-way length5 m16.4 ft | Conductor1.5 mm²AWG 16 · 25 A table | Design current0.5 A | Drop / allowance0.23% / 3% | |
| C7 · Main Battery Switch B ↔ Positive Bus Bar + | One-way length2 m6.6 ft | Conductor16 mm²AWG 6 · 120 A table | Design current23.5 A | FuseNo cable fuse set | Drop / allowance0.40% / 3% |
| C8 · Whale Universal Pump + ↔ Positive Bus Bar 3 + | One-way length1 m3.3 ft | Conductor1.5 mm²AWG 16 · 25 A tablePinned choice | Design current6 A | Fuse7.5 A | Drop / allowance0.55% / 3% |
| C9 · USB-C PD Outlet (60W) + ↔ Positive Bus Bar 5 + | One-way length2 m6.6 ft | Conductor1.5 mm²AWG 16 · 25 A tablePinned choice | Design current5.5 A | Fuse7.5 A | Drop / allowance1.00% / 3% |
| C10 · Victron Orion-Tr Smart 12/12-18 IN − ↔ Junction | One-way length50 cm1.6 ft | Conductor1.5 mm²AWG 16 · 25 A table | Design current0 A | Drop / allowance0.00% / 3% | |
| C11 · Flexible 100 W Panel − ↔ Junction | One-way length90 cm3 ft | Conductor1.5 mm²AWG 16 · 25 A table | Design current5.6 A | Drop / allowance0.65% / 3% | |
| C12 · Victron Orion-Tr Smart 12/12-18 OUT − ↔ Junction | One-way length50 cm1.6 ft | Conductor1.5 mm²AWG 16 · 25 A table | Design current18 A | Drop / allowance1.75% / 3% | |
| C13 · 12V LED Downlight + ↔ Positive Bus Bar 1 + | One-way length30 cm1.0 ft | Conductor1.5 mm²AWG 16 · 25 A table | Design current0.3 A | FuseNo cable fuse set | Drop / allowance0.01% / 10% |
| C14 · 12V LED Downlight + ↔ Positive Bus Bar 2 + | One-way length50 cm1.6 ft | Conductor1.5 mm²AWG 16 · 25 A table | Design current0.3 A | FuseNo cable fuse set | Drop / allowance0.01% / 10% |
| C15 · Positive Bus Bar 2 + ↔ Main Battery Switch A | One-way length50 cm1.6 ft | Conductor16 mm²AWG 6 · 120 A table | Design current23.5 A | FuseNo cable fuse set | Drop / allowance0.10% / 3% |
| C16 · Positive Bus Bar 1 + ↔ Eberspächer Airtronic D2 + | One-way length1 m3.3 ft | Conductor1.5 mm²AWG 16 · 25 A tablePinned choice | Design current3 A | Fuse20 A | Drop / allowance0.27% / 3% |
| C17 · Bilge Pump 1100 GPH + ↔ Positive Bus Bar 3 + | One-way length1 m3.3 ft | Conductor1.5 mm²AWG 16 · 25 A tablePinned choice | Design current3.5 A | Fuse7.5 A | Drop / allowance0.32% / 3% |
| C18 · Negative Bus Bar − ↔ Negative Bus Bar 3 − | One-way length1 m3.3 ft | Conductor10 mm²AWG 8 · 80 A table | Design current17.5 A | Drop / allowance0.24% / 3% | |
| C19 · Whale Universal Pump − ↔ Negative Bus Bar 3 − | One-way length50 cm1.6 ft | Conductor1.5 mm²AWG 16 · 25 A table | Design current6 A | Drop / allowance0.27% / 3% | |
| C20 · USB-C PD Outlet (60W) − ↔ Negative Bus Bar 4 − | One-way length50 cm1.6 ft | Conductor1.5 mm²AWG 16 · 25 A table | Design current5.5 A | Drop / allowance0.25% / 3% | |
| C21 · Negative Bus Bar 1 − ↔ Eberspächer Airtronic D2 − | One-way length1 m3.3 ft | Conductor1.5 mm²AWG 16 · 25 A table | Design current3 A | Drop / allowance0.27% / 3% | |
| C22 · Negative Bus Bar 3 − ↔ Bilge Pump 1100 GPH − | One-way length1 m3.3 ft | Conductor1.5 mm²AWG 16 · 25 A table | Design current3.5 A | Drop / allowance0.32% / 3% | |
| C23 · Negative Bus Bar 2 − ↔ Negative Bus Bar − | One-way length2 m6.6 ft | Conductor16 mm²AWG 6 · 120 A table | Design current23.5 A | Drop / allowance0.40% / 3% | |
| C24 · Engine 36HP — Volvo Penta MD17C Block GND − ↔ 80 Ah Start Battery − | One-way length1.5 m4.9 ft | Conductor70 mm²AWG 2/0 · 330 A table | Design current150 A | Drop / allowance0.88% / 3% | |
| C25 · 80 Ah Start Battery − ↔ Victron SmartShunt 500A LOAD − | One-way length50 cm1.6 ft | Conductor16 mm²AWG 6 · 120 A table | Design current41.5 A | Drop / allowance0.18% / 3% | |
| C26 · USB-C PD Outlet (60W) + ↔ Positive Bus Bar 4 + | One-way length50 cm1.6 ft | Conductor1.5 mm²AWG 16 · 25 A tablePinned choice | Design current5.5 A | Fuse7.5 A | Drop / allowance0.25% / 3% |
| C27 · Dometic CRX-65 Fridge + ↔ Positive Bus Bar 3 + | One-way length3 m9.8 ft | Conductor4 mm²AWG 11 · 45 A table | Design current5.5 A | FuseNo cable fuse set | Drop / allowance0.56% / 3% |
| C28 · Dometic CRX-65 Fridge − ↔ Negative Bus Bar 5 − | One-way length3 m9.8 ft | Conductor4 mm²AWG 11 · 45 A table | Design current5.5 A | Drop / allowance0.56% / 3% | |
| C29 · 80 Ah Start Battery + ↔ Engine 36HP — Volvo Penta MD17C Starter + | One-way length1.5 m4.9 ft | Conductor70 mm²AWG 2/0 · 330 A table | Design current150 A | FuseNo cable fuse set | Drop / allowance0.94% / 3% |
| C30 · Victron SmartShunt 500A LOAD − ↔ Negative Bus Bar − | One-way length50 cm1.6 ft | Conductor16 mm²AWG 6 · 120 A table | Design current41.5 A | Drop / allowance0.18% / 3% | |
| C31 · Victron SmartShunt 500A B+ sense ↔ Positive Bus Bar + | One-way length50 cm1.6 ft | Conductor1.5 mm²AWG 16 · 25 A tablePinned choice | Design current0 A | Fuse2 A | Drop / allowance0.00% / 3% |
| C32 · Victron Orion-Tr Smart 12/12-18 OUT + ↔ 100 Ah LiFePO4 + | One-way length50 cm1.6 ft | Conductor1.5 mm²AWG 16 · 25 A tablePinned choice | Design current18 A | Fuse25 A | Drop / allowance1.64% / 3% |
| C33 · 100 Ah LiFePO4 − ↔ Victron SmartShunt 500A BATT − | One-way length50 cm1.6 ft | Conductor6 mm²AWG 10 · 60 A table | Design current41.5 A | Drop / allowance0.95% / 3% | |
| C34 · Victron MPPT 100/30 BATT + ↔ Positive Bus Bar + | One-way length50 cm1.6 ft | Conductor4 mm²AWG 11 · 45 A tablePinned choice | Design current30 A | Fuse40 A | Drop / allowance1.03% / 3% |
| C35 · 12V Reading/Wall Lamp + ↔ Positive Bus Bar 4 + | One-way length1 m3.3 ft | Conductor1.5 mm²AWG 16 · 25 A tablePinned choice | Design current0.3 A | Fuse1 A | Drop / allowance0.02% / 10% |
| C36 · 12V Reading/Wall Lamp + ↔ Positive Bus Bar 3 + | One-way length1 m3.3 ft | Conductor1.5 mm²AWG 16 · 25 A tablePinned choice | Design current0.3 A | Fuse1 A | Drop / allowance0.02% / 10% |
| C37 · Positive Bus Bar + ↔ Positive Bus Bar 4 + | One-way length1 m3.3 ft | Conductor4 mm²AWG 11 · 45 A tablePinned choice | Design current11.5 A | Fuse15 A | Drop / allowance0.39% / 3% |
| C38 · USB-C PD Outlet (60W) − ↔ Negative Bus Bar 2 − | One-way length1 m3.3 ft | Conductor1.5 mm²AWG 16 · 25 A table | Design current5.5 A | Drop / allowance0.50% / 3% | |
| C39 · USB-C PD Outlet (60W) + ↔ Positive Bus Bar 2 + | One-way length1 m3.3 ft | Conductor1.5 mm²AWG 16 · 25 A tablePinned choice | Design current5.5 A | Fuse7.5 A | Drop / allowance0.50% / 3% |
| C40 · 12V Reading/Wall Lamp − ↔ Negative Bus Bar 4 − | One-way length1 m3.3 ft | Conductor1.5 mm²AWG 16 · 25 A table | Design current0.3 A | Drop / allowance0.02% / 10% | |
| C41 · 12V Reading/Wall Lamp − ↔ Negative Bus Bar 3 − | One-way length1 m3.3 ft | Conductor1.5 mm²AWG 16 · 25 A table | Design current0.3 A | Drop / allowance0.02% / 10% | |
| C42 · USB-C PD Outlet (60W) − ↔ Negative Bus Bar 1 − | One-way length1 m3.3 ft | Conductor1.5 mm²AWG 16 · 25 A table | Design current5.5 A | Drop / allowance0.50% / 3% | |
| C43 · USB-C PD Outlet (60W) + ↔ Positive Bus Bar 1 + | One-way length1 m3.3 ft | Conductor1.5 mm²AWG 16 · 25 A tablePinned choice | Design current5.5 A | Fuse7.5 A | Drop / allowance0.50% / 3% |
| C44 · Negative Bus Bar − ↔ Negative Bus Bar 4 − | One-way length1 m3.3 ft | Conductor2.5 mm²AWG 13 · 35 A table | Design current11.5 A | Drop / allowance0.63% / 3% | |
| C45 · Positive Bus Bar + ↔ Positive Bus Bar 2 + | One-way length1 m3.3 ft | Conductor10 mm²AWG 8 · 80 A tablePinned choice | Design current6 A | Fuse10 A | Drop / allowance0.08% / 3% |
| C46 · 12V LED Downlight − ↔ Negative Bus Bar 2 − | One-way length1 m3.3 ft | Conductor1.5 mm²AWG 16 · 25 A table | Design current0.3 A | Drop / allowance0.02% / 10% | |
| C47 · 12V LED Downlight − ↔ Negative Bus Bar 1 − | One-way length80 cm2.6 ft | Conductor1.5 mm²AWG 16 · 25 A table | Design current0.3 A | Drop / allowance0.02% / 10% | |
| C48 · Lanterns (LED) + ↔ Positive Bus Bar 1 + | One-way length5.5 m18 ft | Conductor1.5 mm²AWG 16 · 25 A tablePinned choice | Design current0.5 A | Fuse1 A | Drop / allowance0.25% / 3% |
| C49 · Positive Bus Bar + ↔ 100 Ah LiFePO4 + | One-way length1 m3.3 ft | Conductor25 mm²AWG 4 · 160 A table | Design current41.5 A | FuseNo cable fuse set | Drop / allowance0.23% / 3% |
| C50 · Victron MPPT 100/30 BATT + ↔ Victron SmartShunt 500A B+ sense | One-way length1 m3.3 ft | Conductor1.5 mm²AWG 16 · 25 A tablePinned choice | Design current0 A | Fuse2 A | Drop / allowance0.00% / 3% |
| C51 · Engine 36HP — Volvo Penta MD17C Alt B+ ↔ Victron Orion-Tr Smart 12/12-18 IN + | One-way length1 m3.3 ft | Conductor6 mm²AWG 10 · 60 A tablePinned choice | Design current40 A | Fuse50 A | Drop / allowance1.94% / 3% |
| C52 · 200 W Solar Panel + ↔ Junction | One-way length50 cm1.6 ft | Conductor1.5 mm²AWG 16 · 25 A table | Design current8.5 A | FuseNo cable fuse set | Drop / allowance0.55% / 3% |
| C53 · USB-C PD Outlet (60W) − ↔ Negative Bus Bar 2 − | One-way length1 m3.3 ft | Conductor1.5 mm²AWG 16 · 25 A table | Design current5.5 A | Drop / allowance0.50% / 3% |
Component table and exact example assumptions
| Component | Ratings, role and assumptions |
|---|---|
| 80 Ah Start BatteryPlanning placeholder | 12 V · 80 Ah Cranking battery for diesel/petrol engine. |
| Main Battery SwitchPlanning placeholder | Single-pole disconnect on positive bus. |
| Flexible 100 W PanelPlanning placeholder | 18 V · 5.6 A rated / planning output · 100 W · 21.6 V STC Voc |
| Victron MPPT 100/30SmartSolar 100/30 | 30 A rated / planning output MPPT solar charge controller. 30A output, max 440W @ 12V / 880W @ 24V, 100V PV. Bluetooth built in; 12/24V battery auto-detect. |
| JunctionPlanning placeholder | A wire splice — any number of cables can meet here. Born from a cable dropped into empty space; promotes to a real junction once a second cable lands on it. |
| JunctionPlanning placeholder | A wire splice — any number of cables can meet here. Born from a cable dropped into empty space; promotes to a real junction once a second cable lands on it. |
| Bilge Pump 1100 GPHPlanning placeholder | 3.5 A load allowance Auto float-switch bilge pump, ~3.5A while running. |
| 200 W Solar PanelPlanning placeholder | 24 V · 8.5 A rated / planning output · 200 W |
| JunctionPlanning placeholder | A wire splice — any number of cables can meet here. Born from a cable dropped into empty space; promotes to a real junction once a second cable lands on it. |
| Positive Bus BarPlanning placeholder | Positive bus bar — common feed with multiple output studs. |
| Lanterns (LED)Planning placeholder | 0.5 A load allowance · 6 W Modern LED navigation lights — port, starboard, stern and masthead. Low draw, suitable for night passages. |
| Negative Bus BarPlanning placeholder | Negative bus bar — common return with multiple output studs. |
| Eberspächer Airtronic D2Airtronic D2 | 3 A load allowance · 34 W 2.2 kW diesel air heater. Runs on roughly 8–34 W (under 3 A at 12 V) depending on heat level; the glow pin draws about 100 W (~8 A) for the first minutes of each start. |
| Engine 36HP — Volvo Penta MD17CMD17C | 150 A load allowance · 55 A rated / planning output Volvo Penta MD17C — 36 HP / 26.5 kW @ 2400 RPM, 3-cyl. 1.4 kW starter cranks at ~150 A (~300 A inrush); alternators range from 35 to 55 A, with higher-output retrofits common. Very common in 30–35 ft Swedish cruisers (Hallberg-Rassy, Najad, Maxi). |
| 12V LED DownlightPlanning placeholder | 0.25 A load allowance · 3 W 3W warm-white downlight. |
| Whale Universal PumpUniversal | 6 A load allowance On-demand fresh-water pressure pump for boats and caravans. A built-in pressure switch starts it when a tap opens and stops it at cut-out pressure, so it runs only minutes per day. Whale's 8–12 L/min pressure pumps draw roughly 4–6 A at 12 V. |
| USB-C PD Outlet (60W)Planning placeholder | 5.5 A load allowance · 60 W |
| 12V LED DownlightPlanning placeholder | 0.25 A load allowance · 3 W 3W warm-white downlight. |
| Victron Orion-Tr Smart 12/12-18Orion-Tr Smart 12/12-18 | 18 A rated / planning output Isolated 18A DC-DC charger from start to house battery. Detects engine run from the input voltage and charges with a three-stage algorithm, set up over Bluetooth. |
| Positive Bus BarPlanning placeholder | Positive bus bar — common feed with multiple output studs. |
| Negative Bus BarPlanning placeholder | Negative bus bar — common return with multiple output studs. |
| Positive Bus BarPlanning placeholder | Positive bus bar — common feed with multiple output studs. |
| Negative Bus BarPlanning placeholder | Negative bus bar — common return with multiple output studs. |
| Victron SmartShunt 500ASmartShunt 500A/50mV (IP21) | 500 A/50 mV battery shunt with Bluetooth and a VE.Direct port, no display. Reads out through the VictronConnect app or a GX device; the aux input can monitor a second battery, midpoint or temperature. |
| USB-C PD Outlet (60W)Planning placeholder | 5.5 A load allowance · 60 W |
| Dometic CRX-65 FridgeCRX-65 | 5.5 A load allowance · 66 W Built-in compressor fridge/freezer for 12 or 24 V systems, rated 5.5 A / 66 W at 12 V. Averaged consumption is about 1.4–1.8 Ah per hour depending on ambient temperature — roughly 35–45 Ah/day. |
| 100 Ah LiFePO4Planning placeholder | 12.8 V · 100 Ah Generic 12V 100Ah lithium iron phosphate house battery. |
| USB-C PD Outlet (60W)Planning placeholder | 5.5 A load allowance · 60 W |
| USB-C PD Outlet (60W)Planning placeholder | 5.5 A load allowance · 60 W |
| 12V Reading/Wall LampPlanning placeholder | 0.25 A load allowance · 3 W Adjustable LED reading/wall lamp, typical bunk or saloon fixture. |
| 12V Reading/Wall LampPlanning placeholder | 0.25 A load allowance · 3 W Adjustable LED reading/wall lamp, typical bunk or saloon fixture. |
| Positive Bus BarPlanning placeholder | Positive bus bar — common feed with multiple output studs. |
| Negative Bus BarPlanning placeholder | Negative bus bar — common return with multiple output studs. |
Before adapting an example
What these drawings assume
Both drawings come from the same boat demo project. The first keeps its engine and battery area, load distribution panel and bow; the full demo also includes solar, cabin and stern circuits. Equipment, connections, cable lengths and protection choices are retained from the demo, with cable sizes recalculated by Crimp. The demo is a starting project with unresolved engine findings, not a verified installation. Switching controls, bonding, shore power and the actual installation environment need separate review.
- Equipment and saved settings come from the boat demo. Battery acceptance, BMS controls, charging configuration, solar compatibility and runtime have not been verified for an actual installation.
- Battery-post and cable fuse choices are retained from the demo. Check the actual device, holder, interrupt rating and placement, and resolve the engine findings before adapting the project.
- Lengths are physical one-way conductor runs. Voltage drop includes a return; shared paths use the engine’s conservative current bounds, not a prediction of simultaneous power flow. The calculation does not verify unequal shared-return lengths as one complete circuit. AWG labels are approximate table counterparts to metric conductors, not identical cross-sectional areas.
- Sizing uses Crimp’s ABYC-based tables for 105°C copper outside engine spaces, with no additional heat or bundling derating in these examples. Explicit 3% circuit targets and 10% cabin-light allowances are planning choices; terminals on placeholders carry generic planning limits, not verified connector ratings. US RV, UK campervan and Australian 4WD wording does not establish UK or AS/NZS installation compliance.
Adding monitoring or larger distribution changes the current paths. Read the SmartShunt return-path example and Lynx Distributor example, including their conservative series-current bounds and unresolved protection. The model pages keep those limitations visible.
Demo equipment
Component references
Read the catalog notes and linked documentation for the equipment used in the boat demo. Imported settings are example choices to review.
Crimp component libraryVolvo Penta MD17C engineEngine, starter and alternator terminals used in the boat demo.Crimp component libraryOrion-Tr Smart 12/12-18The demo’s DC-DC charger, with model notes and linked documentation.Crimp component librarySmartShunt 500 ABattery and system sides of the house-bank shunt.Crimp component librarySmartSolar MPPT 100/30Solar controller in the full boat demo.