RNG-DCC1212-40
Renogy DCC1240 wiring diagram
RNG-DCC1212-40: 40A non-isolated 12V-to-12V DC-DC charger, without solar input. D+ is required for operation; applying 12V to LC limits output to 20A.
- Compatible systems
- 12 V
- Rated output
- 40 A
Wiring diagram
How the DCC1240 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
- 16 mm² · 6 AWG
- Example fuse
- 50 A
- Design current
- 40 A
- Voltage drop
- 2.2%
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 16 mm² (6 AWG) marine cable
- Terminations for 16 mm² cable, matched to the equipment's screw terminals, leads or studs
- 50 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 1.4), checked 2026-10-01. Manufacturer documentation →
What does the DCC1240 do?
This entry is RNG-DCC1212-40 / DCC1212-40, the legacy 12 V-to-12 V, 40 A onboard charger covered by Renogy’s 20/40/60 A Version 1.4 manual. It has no solar input and is distinct from newer RBC40D1U and dual-input MPPT products. The technical table gives an 8–16 V input battery range and 500 W rated maximum power.
How do the connections map?
Crimp’s START + / START − are the INPUT pair; BATT + / BATT − are the OUTPUT pair to the house battery. The two circuits share a common negative; separate terminals do not mean galvanic isolation. The manual describes a common grounding point and says not to use the charger body as the grounding connection.
The drawing omits D+ ignition, LC current limit, five DIP switches, and the RJ11 temperature-sensor port. D+ is required for this charger to operate, not merely an optional smart-alternator setting. Connect it to the vehicle’s appropriate engine-running signal as established from that vehicle’s wiring documentation.
What protection and wire sizes are specified?
Renogy’s 40 A wiring row specifies 60 A input protection and 50 A output protection, with wording allowing a close available rating. Its 0–3 m reference uses 6 AWG input and 8 AWG output; longer runs require the larger sizes in the table. Input current can be up to 50% above output current, so do not size both sides as though they each carry only 40 A.
The connections are M6 × 10 mm. Protect both battery-fed positive cables and confirm actual conductor ampacity, routing and voltage drop. The source’s terminal-torque line uses unusually small values; obtain confirmation for the installed terminal before applying a guessed torque.
How are charging current and chemistry configured?
Applying 12 V to LC halves the rated output to 20 A. This can help match a smaller battery or available alternator capacity, but it is a control input, not a power feed.
Set the five DIP switches using the manual’s exact table: ON is downward when facing the switches, and SW5 ON selects lead acid; OFF selects lithium. Lead-acid profiles use absorption and float; lithium uses absorption without float. Match voltage to the battery maker’s requirements and do not use temperature compensation with lithium.
Install close to the house battery, horizontally or vertically on a firm surface, with at least 50 mm clearance, ventilation and protection from moisture, dust and excessive heat. Clear fan airflow is necessary for full output.
Fit check
Connect it to the rest of your system.
Describe your setup to draft a system with RNG-DCC1212-40 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
RNG-DCC1212-40: 40A non-isolated 12V-to-12V DC-DC charger, without solar input. D+ is required for operation; applying 12V to LC limits output to 20A.
- Compatible systems
- 12 V
- Rated output
- 40 A
- Planning charge current
- 38 A
Terminal map
Catalog connection points, current direction and planning limits. Check the manufacturer's pinout and connector ratings before installation.
START +
positive · input
START −
negative · input
BATT +
positive · output
BATT −
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.
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Plan your installation with DCC1240.
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