Buck-Boost DC-DC 100A
Victron Buck-Boost 100A wiring diagram
Programmable Buck-Boost for service-battery charging from 10–30 V vehicle systems. Maximum output is 100 A at 12 V or 50 A at 24 V; configure engine detection and the alternator-current limit.
- Rated output
- 100 A
Wiring diagram
How the Buck-Boost 100 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
- 35 mm² · 2 AWG
- Example fuse
- 125 A
- Design current
- 100 A
- Voltage drop
- 2.5%
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.
Supporting parts
- 6.1 m total of 35 mm² (2 AWG) marine cable
- Terminations for 35 mm² cable, matched to the equipment's screw terminals, leads or studs
- 125 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. Version 11 — September 23rd, 2025), checked 2026-10-01. Manufacturer documentation →
Which Buck-Boost is this?
The Buck-Boost 100 A is a programmable converter for charging a service battery from a vehicle system, including smart alternators. Both input and adjustable output cover 10–30 V. The 100 A name is its 12 V output class, not its output at every voltage: the manual lists 50 A at 24 V, and its conversion table lists 50 A for 12 V to 24 V. See printed page 9 before selecting a conversion.
How do the connections map?
Crimp's IN + maps to physical IN, OUT + to OUT, and both negative symbols to the single GND connection. This is a common-ground installation. The USB configuration connection, CAN connection, and programmable purple/green control wires are omitted.
Connect the ground paths to the converter, battery, and chassis before connecting either positive. The manual warns that connecting both positives without GND can cause uncontrolled current, and states that the converter has no reverse-polarity protection. The center GND connection is M8; do not infer a tightening torque from that thread size.
Which protection and cables are specified?
For this 100 A model, the manual's under-5 m table specifies 50 mm² cable and 125 A fuses on 12 V sides, or 80 A fuses on 24 V sides. Apply each row to the voltage of that side; a mixed-voltage installation can need different input and output fuses. Cable environment, length, and fault-current interruption still require checking.
These are manufacturer installation values, not proof that a particular alternator can supply the requested power. The simple symbol does not calculate voltage-dependent input demand or select a conversion mode.
What must be configured?
Use TSConfig over USB to set the output voltage, current limit, undervoltage threshold, and activation method. Printed page 8 limits the commissioning current setting to at most 60% of the vehicle alternator's supplied current; the alternator and vehicle installation can impose a lower limit. Match charging voltage and permissions to the battery and its BMS.
Engine-running detection or the programmable input controls activation. Confirm shutdown with the engine stopped so the starter battery is not drained. Mount in a ventilated space away from salt, moisture, and excessive heat; thermal current limiting is not a substitute for adequate cooling.
Fit check
Connect it to the rest of your system.
Describe your setup to draft a system with Buck-Boost DC-DC 100A 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
Programmable Buck-Boost for service-battery charging from 10–30 V vehicle systems. Maximum output is 100 A at 12 V or 50 A at 24 V; configure engine detection and the alternator-current limit.
- Rated output
- 100 A
- Planning charge current
- 95 A
Terminal map
Catalog connection points, current direction and planning limits. Check the manufacturer's pinout and connector ratings before installation.
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 Buck-Boost 100.
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