I. INTRODUCTION
Thank you for choosing your Digital Duo Charge.
Like our ARS-4 and Max Charge voltage regulators,
the Duo Charge features a programmable micro-
processor with four preset programs to ensure
proper charging for Gel, AGM, Standard
Flooded and Deep-Cycle Flooded batteries.
The addition of an optional battery temper-
ature sensor (MC-TS-B) enables the Duo
Charge to monitor the ambient temperature of the
battery being charged. Should a battery over-temperature
condition occur, the Duo Charge will automatically discontinue charging.
The Duo Charge delivers charging current to a maximum of 30A. Should the secondary bat-
tery bank require charging currents in excess of that amount, the Duo Charge can be used
in conjunction with a solenoid to provide a charging pathway up to the amperage limits of
the alternator or other charging source.
II. INSTALLATION
The Duo Charge is housed in a durable anodized aluminum heat sink. Four pre-drilled
mounting holes enable the Duo Charge to be easily mounted to a bulkhead, stringer or
other flat surface. For optimal viewing of the color-coded LED display, a vertical mount with
the 1/4” spade terminals at the top of the unit (as shown in the drawing at right) is preferred.
Installation is as follows:
1. Mount the Duo Charge in a dry, well-ventilated place. Avoid excess heat and/or vibra-
tion. Avoid locations where Duo Charge or wiring connections could be exposed to
sprayed water or coolant.
2. A pre-made 10-gauge fused wire, with ring terminals at each end, runs between theprimary battery and the Duo
Charge INPUT terminal. Use caution when installing the ring terminal at the house battery.
3. A fused 10-gauge wire with ring terminal and butt connector is supplied. The ring terminal is connected at the
start battery positive with the butt connector crimped to the user-supplie10-gauge wire required to connect to the
OUTPUT terminal on the Duo Charge. A minimum run of eight feet is recommended for the output wire.
4. The Duo Charge must be connected to a common ground source. A 16-gauge BLACK ground wire should be con-
nected between the Ground terminal (marked “ground” in diagram) and the system’s central ground bus.
BATTERY BANKS MUST BE CONNECTED BY A COMMON GROUND!
5. The Duo Charge is equipped with a sleep state which uses minimal current when voltage falls below 13 volts in
a 12-volt system or 26 volts in a 24-volt system. In most cases, this terminal can be connected via 14-gauge wire
to the house battery or the INPUT terminal on the Duo Charge. An ON/OFF toggle can be installed in this wire to
manually shut down the Duo Charge. If using the Duo Charge to control charge flow from a shorepower charg-
er, be sure that the output from the charger to the starting battery is disconnected.
6. The Duo Charge can monitor and respond to battery over-temperature conditions at the starting battery when
optional battery temperature sensor (MC-TS-B) is installed. To install, connect the sensor lug at the negative post
of the starting battery and the 1/4” spade terminals to the positive and negative pins marked TEMP SENSE (+)
and TEMP SENSE (-) on the Duo Charge.
7. Should a larger secondary battery require charging amperage greater than the Duo Charge’s 30-amp rating, the
Duo Charge can be connected to a solenoid. Be sure that the solenoid used is adequate to handle amperages in
excess of the alternator’s rated output. When using a solenoid, cabling between the house and starting batteries
via the solenoid must meet or exceed gauges recommended by the 3% voltage drop chart included in your alter-
nator or regulator’s installation manual. The “Solenoid” terminal should be connected to the ground side of the
solenoid activation relay. To activate the solenoid, install an ON/OFF toggle between the Duo Charge’s
Auto/Manual terminal and system ground. When the toggle is in the ON position, the solenoid drive will go to
ground and the Duo Charge’s internal circuitry will be bypassed.
Digital Duo Charge
Installation and Operator’s Manual
