Charger
Review how the Balmar Digital Duo Charge DDC-12/24 connects, how it operates and which installation requirements apply to this model.
Open this example as a new project. Use your own parts and cable lengths to make the plan yours.
Three-terminal power/reference arrangement, mandatory enable, deliberately short supplied input and >=8 ft output extension need exact common-negative starter-bank diagram; generic four-wire converter example is misleading.
Three-terminal power/reference arrangement, mandatory enable, deliberately short supplied input and >=8 ft output extension need exact common-negative starter-bank diagram; generic four-wire converter example is misleading.
Wiring diagram
Open this example in Crimp to use your own parts and cable lengths. Review the assumptions and installation notes as you adapt the circuit.
Installation notes
Guidance for this model, with sources linked beside the relevant advice.
Verified against the manufacturer's documentation (rev. SUP-0202 Rev B, 12 May 2017), checked 2026-10-01. Manufacturer documentation →
Digital Duo Charge transfers up to 30 A from a charging house bank to the starter bank. Its four output profiles cover flooded, deep-cycle, gel and AGM batteries; the manual does not establish a lithium starter-bank profile. Configure 12 V or 24 V operation to match both banks. With the enable lead permanently supplied, charging begins when input exceeds 13 V in a 12 V system or 26 V in a 24 V system. See enable wiring, PDF p. 3.
Connect the fused input lead to house positive and fused output lead to starter positive. Both banks require a shared negative system. The separate 14 AWG ground wire is the controller reference, not a replacement for the starter bank's heavy negative cable. The ON/OFF lead also needs the chosen enable supply; installing only the large positive cables will not commission the charger.
Both supplied positive leads contain 30 A fuses and use 10 AWG cable. Balmar calls for a short input lead and recommends at least eight feet (2.44 m) of output extension to the starter battery. The manual deliberately uses that wiring arrangement for its dynamic response; shortening everything for appearance changes the specified installation. Mount dry, within reach of the supplied input lead, with the status LEDs visible. See cable instructions, PDF p. 2.
Confirm system voltage and battery profile before enabling, then measure current and starter voltage while the house bank is charging. Demand above 30 A can cause the Duo Charge to stop and retry. Its optional external-solenoid circuit is a distinct installation for high demand; it does not turn the internal converter into a larger charger. Investigate persistent cycling and excessive voltage drop before changing fuses. See operation and overload behavior, PDF p. 5.
Build it out
Add DDC-12/24 to your diagram, then connect your batteries, chargers and loads. Crimp calculates cable sizes and checks the connections as you draw.
Every cable you draw there is sized against ABYC E-11, from the same tables as the reference on this page.
Technical reference
Check the model, ratings and connection points against your own unit before choosing installation hardware.
Check stud sizes, fuse type, run length and how warm the space gets against the gear you actually have before you order.
Catalog connection points, current direction and planning limits. Check the manufacturer's pinout and connector ratings before installation.
HOUSE IN +
in-pos
positive · input
START OUT +
out-pos
positive · output
CONTROL GND
gnd
negative · input
ON/OFF
enable
signal · bidi
BATTERY TEMP
temp
signal · bidi
SOLENOID CONTROL
solenoid
signal · bidi
AUTO / MANUAL
mode
signal · bidi
A dash means a current rating is not specified here.
Method & provenance
Manufacturer specifications describe the equipment. Crimp calculates cable results from the circuit and assumptions you enter.
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
Open this example as a new project. Add your equipment and cable lengths, then review the sizing and checks for your setup.