Charger
Victron Orion-Tr Smart 12/12-18 isolated wiring diagram
Wire the isolated Orion-Tr Smart 12/12-18 between your starter and house banks. See the two protected positive paths and separate negative returns, then set up charging for your battery.
- Compatible systems
- 12 V
- Rated output
- 18 A
Connection essentials
Starter bank → IN
Run the starter supply and return to IN+ / IN−, with protection at the starter battery.
House bank → OUT
Run OUT+ / OUT− to the house bank, with protection at that battery. Check the battery profile first.
Keep isolation intact
IN− and OUT− are separate returns. Joining them bypasses isolation; plan grounding deliberately.
Wiring diagram
How the Orion 18A is wired.
Starter bank → isolated charger → house bank. Both positives need battery-end protection. IN− and OUT− are separate returns.
Both 12 V battery paths use the manual's 60 A external protection and 16 mm² cable from its 5 m table entry for the example's 3.048 m runs. The 60 A fuse rating is not operating current. Keep the isolated input and output returns distinct and configure charger mode before use. Manufacturer installation manual
Edit this wiring exampleHouse-bank output sizing for this example
The sizing panel covers the house-bank output. Review the input circuit and both battery fuses in the diagram.
3 m one way
12 V system
- Wire
- 16 mm² · 6 AWG
- Example fuse
- 60 A
- Design current
- 18 A
- Voltage drop
- 1.0%
Sized against ABYC E-11. The design current is the unit's rated output. 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.
Both 12 V battery paths use the manual's 60 A external protection and 16 mm² cable from its 5 m table entry for the example's 3.048 m runs. The 60 A fuse rating is not operating current. Keep the isolated input and output returns distinct and configure charger mode before use. Manufacturer installation manual
Supporting parts
- 6.1 m total of 16 mm² (6 AWG) marine cable
- Terminations for 16 mm² cable, matched to the equipment's screw terminals, leads or studs
- 60 A fuse and holder on the positive run
- 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.
Verified against the manufacturer's documentation (rev. 14 — 02/2026), checked 2026-09-11. Manufacturer documentation →
How do I connect the isolated Orion-Tr Smart 12/12-18?
Keep the input and output returns separate when preserving isolation. This page covers the isolated ORI121222120 model. Follow the charger-mode connection diagram:
- IN + / IN −: starter-bank supply and return, with a fuse at starter-battery positive.
- OUT + / OUT −: house-bank charge connection and return, with a fuse at house-battery positive.
- Remote H / L: control connections, outside this example's power paths. Follow the manual for your control method.
Connecting IN − to OUT − bypasses the model's galvanic isolation. Check your required grounding arrangement before adapting the drawing.
Do the displayed cable and fuse sizes cover both sides?
The sizing panel summarizes the output-to-house-bank run. The diagram also shows the starter-side input circuit. Both sides need their own cable and protection review; 18 A is the output rating, not an input-current allowance.
The example uses 16 mm² cable and a 60 A fuse on each 12 V side, with 3.048 m / 10 ft one-way runs. These are choices from the 5 m bracket of Victron's cable-and-fuse table. Review them for your actual route and installation conditions. A 60 A fuse is protection, not a prediction of input current; the DC-DC charger size tool compares output rating with vehicle-side demand.
What should I set before charging the house battery?
Select charger mode and the correct battery profile in VictronConnect before connecting the battery to be charged. Fixed-voltage power-supply mode is a different operating mode. Follow the manual's connection and setup sequence.
Mount vertically with terminals down and airflow around the fins. The 18 A rating applies at 40°C; hotter installations reduce output.
Why does charging stop while the engine is running?
The charger infers engine operation from input voltage. A smart alternator can lower that voltage while driving. Check VictronConnect's status, input wiring and the vehicle-specific engine detection settings.
Some vehicles need a genuine engine-running signal through the specified remote wiring. An ignition feed can remain live with the engine stopped; it is not equivalent. Follow the manual's signal guidance and leave engine detection enabled when using its external-signal override. Disabling detection can drain the starter battery.
Can Bluetooth show the charging current?
No. This Orion-Tr Smart does not display input/output current or have a VE.Direct port. Bluetooth configures and monitors the available status data. See the notes in the isolated model specifications.
Add a SmartShunt or BMV-712 to measure net house-bank current. For a complete layout, open the dual-battery example. If separate negatives are unnecessary, compare the non-isolated Orion XS.
Fit check
Connect it to the rest of your system.
Describe your setup to draft a system with Orion-Tr Smart 12/12-18 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
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.
- Compatible systems
- 12 V
- Rated output
- 18 A
- Planning charge current
- 17 A
Terminal map
IN + / IN − belong to the starter side; OUT + / OUT − belong to the house side. This is the isolated 12/12-18 model. Remote on/off and engine-detection setup are outside this power-path drawing. Current limits are catalog planning values.
IN +
positive · input
IN −
negative · input
OUT +
positive · output
OUT −
negative · output
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 Orion 18A.
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.