House
Bank
St
ar
b
o
ar
d
B
at
te
ry
S
en
se
+
Power
Post
1
4
1
2
3
4
R
R
RECOMMENDED CHARGING COMPONENTS
Dual Alternators/Single Engine
Single Max Charge Regulator
Output To Single House Bank
(Engine Battery Charged W/Duo Charge)
18930 59TH AVE. NE
ARLINGTON, WA 98223 USA
360 435 6100
WWW.BALMAR.NET
MC-612-H Voltage Regulator
Alternator #1
Alternator #2
DDC-12/24 Digital Duo Charge
Field Output
From MC-612
Engine
Bank
3
2
Wiring Instructions:
When charging a single house battery bank via dual alternators on a single engine, we
recommend the following:
1. Install appropriately sized alternators to support the capacity of the house battery
bank to be charged. We recommend that the combined capacity of the two
alternators should be approximately 25 to 40 percent of the rated battery capacity.
For optimal output and engine performance, we recommend that alternators be of
same, or similar output capacity.
2. When controlling dual alternators on a single engine, the only Balmar voltage
regulators to be used are the Max Charge MC-612 (for 12-volt applications), or the
MC-624 (for 24-volt applications). The field output from the Max Charge regulator
must be split to two equal length field wires. This can be accomplished by using a
wire tap to the regulator's existing field wire to to integrate the second field wire,
or to use a three-way (tee) connector connected to the field wire in ther regulator
harness, with each of the adjoining terminals supplying a field wire to each
alternator. In either case, termination should be made as close to the regulator
wiring plug as possible (within 1-1/2" to 2" of the plug).
3. Positive output cables from both alternators can be run direct to the house battery,
or from each alternator to a power post, with a common run to the house battery
bank. Using the power post as a central location for the combined alternator
outputs to meet makes it possible to ensure that cable runs from both alternators
are of equal length, minimizing the possibility of resistance compromising output
from either alternator. Use 3% voltage drop chart to determine proper cable size.
Use amperage capacity of combined alternators to determine ampacity, and cable
size required. See ABYC recommendations for fusing.
4. Connect regulator power (RED) and positive battery sense wires
to the central power post, alternator positive output post, or
directly to house battery positive to ensure accurate voltage
sensing. Increase the size of the power (RED) wire to 12-gauge if
wire length is increased beyond harness length.
5. Install Digital Duo Charge, as indicated at right, to provide
controlled charging current to the engine start battery. The
Digital Duo Charge's ON/OFF wire can be connected to the same
ignition circuit supplying the Max Charge
voltage regulator if Duo Charge is only required
while charging with the alternator and
regulator. Should the Duo Charge be required
to supply charging current from other charge
sources, the ON/OFF wire can be connected
directly to the house battery positive, or to the
input terminal on the Duo Charge being
supplied by the house battery bank. If used to
supply charging current from charging sources
other than alternator and regulator, ensure that
all charge sources (shorepower, solar, wind, etc),
all be directed to the house battery only. See
Duo Charge installation instructions for
additional wiring details.
Summary of Contents for Max Charge MC-612
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