Balmar Digital Duo Charge DDC-12/24 connections

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.