Charger
Dual-input 40A DC-DC charger with MPPT solar input. Vehicle input accepts 9–32V so it runs under 12V or 24V alternators; Redarc specifies a 60A input fuse.
The reference run on this page is 1 m one way, sized against ABYC E-11. Your own run will differ, and the canvas sizes that one.
Wiring diagram
The drawing shows where the feed, the return and the fuse land on this part. The starter uses the same reference circuit and sizing assumptions. Read the installation notes for manufacturer requirements before adapting the runs.
The starter uses the manual's 60 A battery fuses, a 16 mm² conductor choice above its minimum area, and a 1 m charger-to-auxiliary-battery run. These are pinned example choices; review them after edits. The engine's generic DC-DC input-current estimate does not model this charger's voltage conversion or solar sharing. Manufacturer installation manual
Open starter in CrimpBuild it out
Open the canvas with BCDC1240D already placed, then add your batteries, charging, distribution and loads around it.
Every cable you draw there is sized against ABYC E-11, from the same tables as the reference on this page.
Technical reference
The catalog facts for this part, which terminal takes what, and the hardware you'll want around it. Check the nameplate on your own unit before you order.
1 m reference run
12 V system
Sized against ABYC E-11. Boats built to UK or EU rules answer to ISO 13297 — check these figures against it before you build. The design current is the unit's rated output. The length is one way; voltage drop includes an equal-length return. The shared starter uses 3.048 m (10 ft) runs unless a shorter run is stated. These are example assumptions for you to adapt to your own installation.
The starter uses the manual's 60 A battery fuses, a 16 mm² conductor choice above its minimum area, and a 1 m charger-to-auxiliary-battery run. These are pinned example choices; review them after edits. The engine's generic DC-DC input-current estimate does not model this charger's voltage conversion or solar sharing. Manufacturer installation manual
Check stud sizes, fuse type, run length and how warm the space gets against the gear you actually have before you order.
These are logical circuit connections. ALT + maps to the red vehicle lead, PV + to yellow, and BATT + to brown. PV − and BATT − represent the shared black ground connection, not separate physical negative leads. The listed currents are catalog planning limits, not manufacturer wire ratings. Trigger and profile wires are described in the installation notes.
ALT +
alt-pos
positive · input
PV +
pv-pos
positive · input
PV −
pv-neg
negative · input
BATT +
out-pos
positive · output
BATT −
out-neg
negative · output
Field notes
What we've read and heard about installing this exact part. These are notes, kept apart from the numbers Crimp works out.
This is the BCDC1240D, BCDC Classic40, a 40 A charger for a 12 V auxiliary battery. The D suffix matters. REDARC's model specification identifies separate vehicle and MPPT solar inputs, and 60 A protection on both battery paths. The vehicle can be 12 V or 24 V; the output is for a 12 V battery. Classic, Core and Alpha are separate product families.
For a 4WD dual battery setup, the starter battery supplies the red vehicle-positive lead through a battery-end fuse. The brown output lead charges auxiliary positive through its own battery-end fuse. The black lead is common ground. The starter models this vehicle path with a 12 V AGM source and 200 Ah auxiliary bank; solar is left disconnected.
All negative connections must share an electrical ground. On vehicles with starter-battery current sensing, the required return may be a designated chassis point rather than the battery-negative post. Use REDARC's common-ground diagrams and the vehicle's instructions. Crimp's logical negative connections are not a physical harness pinout.
The Classic manual, pages 6 and 14–16, specifies 60 A input and output fuses, recommends MIDI protection and requires at least 13.56 mm² conductor area for 1–5 m. The example selects 16 mm² and pins the manufacturer's fuse rating.
The auxiliary-battery run is 1 m (about 3.3 ft), following the short-output-run guidance. The vehicle feed is 3.048 m (10 ft). Each includes an equal-length return for the example calculation. The reference panel describes the output circuit; input current is a generic engine estimate, not a voltage-conversion or solar-sharing simulation. Replace placeholder batteries and review pinned hardware after changing the layout.
Yellow accepts unregulated solar; select the blue trigger and orange battery-profile connections from the manual. These control wires and optional solar are outside the starter. A removable canopy or caravan also needs a common return across its connector; use the separate manufacturer diagram for that layout.
Use the lithium conversion guide to plan battery changes and the fuse checker for fault-current and exact-part checks. The ABYC-based methodology does not establish AS/NZS installation compliance.
See the BCDC1240D dual-battery system example for the vehicle source, auxiliary bank, distribution and protected loads together, including unresolved protection checks.
Verified against the manufacturer's documentation (rev. INST173-3 EN), checked 2026-09-11. Manufacturer documentation →
Method & provenance
The manufacturer publishes some of these numbers and Crimp works out the rest. It's worth knowing which is which.
From the maker
Manufacturer, model, ratings and which terminal does what come from the catalog. A newer revision, or the nameplate on the unit in your hand, can say something different — when it does, the nameplate wins.
ABYC E-11
Sized against ABYC E-11. Boats built to UK or EU rules answer to ISO 13297 — check these figures against it before you build. The run length and the current above are what drive the result. Crimp doesn't know how warm your space gets; draw the cable inside an engine-bay zone on the canvas and it sizes for the heat.
Next step
It lands on the canvas already placed. Add what it connects to, and every run gets its wire and fuse as you draw.