SURE POWER MARINE ISOLATOR INSTRUCTIONS
FOR INBOARD APPLICATIONS
(This instruction sheet is to be used in conjunction with Isolator Instruction #180012)
The installation of a Sure Power Battery Isolator in a marine inboard application is very similar to that of a
typical automotive installation, with a few minor exceptions. The difference arises when the use of a battery
selector switch is required or desired.
When installing a Battery Isolator in an application not requiring the use of battery selector switches, please
follow the Sure Power Multi-Battery Isolator Application and Installation Instructions (#180012), included in
this package. When using more than one charging source, please refer to the group installation instructions
for that particular alternator. Most marine installations will fall under Group 1 or Group 3 instructions. Typical
marine wiring diagrams without selector switches are shown in figures 1, 2 and 3.
Battery Isolators may be used with selector switches. Isolators actually enhance battery switch applications
because each battery can still be charged independently when the switch is connecting either battery.
Typical Isolator with battery switch applications are shown in figures 4 and 5. These diagrams are only two of
the possible connection alternatives.
NOTE: Be sure that the alternator has remote sense capability. Most single-wire Delco alternators do
not have this provision. The voltage regulator must sense battery voltage. The sense line should be
connected to the main battery terminal of the Isolator. Call the Sure Power customer-service department if a
particular application arises which is not covered.
NOTE: If using a circuit breaker in the main battery line, Sure Power recommends connecting the voltage
regulator sense line to the main battery terminal of the Isolator.
Please refer to ABYC and BIA rules and recommendations regarding proper marine wiring sizes and proper
circuit breaker protection.
Inboard Marine Isolator Application Chart
Number of
Charging Sources
Maximum
Alternator Output
Number of
Battery Banks
Sure Power Isolator
Model Number
1
70 Amps
70 Amps
95 Amps
95 Amps
120 Amps
120 Amps
160 Amps
160 Amps
2
3
2
3
2
3
2
3
702
703
952
1203
1202
1203
1602
1603
2
70 Amps
70 Amps
120 Amps
120 Amps
2
3
2
3
2702
2703
3202
3203
For Group 2 Applications, add a "3A" suffix to the model number.
For Group 3 Applications, add an "R" suffix to the model number.
LITHO IN USA
PAGE 1
INSTRUCTION 180119A 0102
Sure Power
Battery Isolator
Sure Power
Battery Isolator
Circuit
Breaker
Circuit
Breaker
Circuit
Breaker
ENGINE
BATTERY
ONLY
Circuit
Breaker
Circuit
Breaker
ENGINE
BATTERY
ONLY
AUXILIARY
BATTERY
AUXILIARY
BATTERY #1
To accessory
distribution panel #1
To accessory
distribution panel
Figure 1
One alternator, two battery banks without selector switch
Applicable Isolator Models: 702, 952, 1202, 1602
To accessory
distribution panel #2
Figure 2
One alternator, three battery banks without selector switch
Applicable Isolator Models: 703, 1203, 1603
Sure Power
Battery Isolator
Circuit
Breaker
Circuit
Breaker
ENGINE
BATTERY #1
Circuit
Breaker
AUXILIARY
BATTERY
Sure Power
Battery Isolator
Circuit
Breaker
Selector
Switch
To accessory
distribution panel
ENGINE
BATTERY #2
AUXILIARY
BATTERY #2
Circuit
Breaker
BATTERY #1
BATTERY #2
To accessory
distribution panel
Figure 3
Two alternator, two or three battery banks without
selector switch
Applicable Isolator Models: 2702, 3202 (two battery banks)
2703, 3203 (three battery banks)
Figure 4
One alternator, two battery banks with selector switch
Applicable Isolator Models: 702, 952, 1202, 1602
CB
CB
ENGINE
BATTERY #1
Sure Power
Battery Isolator
Selector Switches
AUXILIARY
BATTERY
To accessory
distribution panel
ENGINE
BATTERY #2
CB
Figure 5
Two alternator, two or three battery banks with selector switch
Applicable Isolator Models: 2702, 3202 (two battery banks)
2703, 3203 (three battery banks)
10189 S.W. Avery Street
LITHO IN USA
Tualatin Oregon 97062
Tel 503.692.5360
PAGE 2
Fax 503.692.9091
www.surepower.com
INSTRUCTION 180119A 0102
RECTIFIER TYPE ISOLATORS FOR MARINE
OUTBOARD ENGINES
Sure Power Rectifier Type Isolators are specifically designed for the latest outboard engines with regulator/rectifier type
alternators. The system allows for the convenience of running one, two or three auxiliary batteries to power all types of
accessories and safety equipment from a single or twin charging source. These special Isolators are designed to
withstand high peak inverse voltages.
ISOLATOR INSTALLATION / NO SELECTOR SWITCH
1. Mount Isolator in a convenient location near the auxiliary battery.
2. Connect a new #10 wire from the "A" terminal of the Isolator to the existing yellow-gray wire junction on the regulator
terminal block. Do not remove any existing wires.
3. Connect a new #10 gauge wire from the #1 terminal of the Isolator to the positive terminal of the auxiliary battery.
4. Connect auxiliary loads to the positive terminal of the auxiliary battery or to the #1 terminal of the Isolator.
5. Connect the negative terminal of the auxiliary battery to a good common negative ground.
6. For two or three battery Isolators, repeat step 3, 4 and 5 for each auxiliary battery.
7. Follow ABYC and BIA recommendations for circuit breaker protection and wire sizes.
ISOLATOR INSTALLATION / NO SELECTOR SWITCH
1. Mount Isolator in a convenient location near outboard motors.
2. Connect a new #10 gauge wire from the "A1" terminal of the Isolator to the existing yellow-gray wire junction on the
#1 motor regulator terminal block. DO NOT REMOVE ANY EXISTING WIRES.
3. Connect a new #10 gauge wire from the "A2" terminal of the Isolator to the existing yellow-gray wire junction on the
#2 motor regulator terminal block. DO NOT REMOVE ANY EXISTING WIRES.
4. Connect a new #10 gauge wire from the "B1" terminal of the Isolator to the existing #1 main battery positive post.
5. Connect a new #10 gauge wire from the "B2" terminal of the Isolator to the existing #2 main battery positive post.
6. Connect a new #10 gauge wire from the "B3" terminal of the Isolator to the new auxiliary battery positive post.
7. Connect the negative posts of all three batteries to a good common negative or ground point.
8. Connect auxiliary loads between ground and the positive post of auxiliary battery.
9. Follow ABYC and BIA recommendations for circuit breaker protection and wire sizes.
ISOLATOR INSTALLATION / WITH
SELECTOR SWITCH
EXPLODED VIEW
REGULATOR
JUNCTION
BLOCK
REGULATOR
RECTIFIER
YELLOW
YELLOW/GRAY
GRAY
PURPLE
TO ALT.
TO ALT.
1. Follow standard Isolator instructions, steps 1 and 2.
2. Step 3 - Connect outputs of Isolator to battery
terminals on selector switch. Example: Isolator output
terminal #1 to selector switch battery terminal #1.
Repeat as required.
3. Follow ABYC and BIA recommendations for circuit
breaker protection and wire sizes.
NEW
EXISTING WIRE
RED
TO STARTER
SOLENOID
LITHO IN USA
TO BATTERY
ISOLATOR
PAGE 3
INSTRUCTION 180119A 0102
SURE POWER MODEL 702
Application: 1 Engine, 2 Battery
No Selector Switch
SURE POWER MODEL 702
Application: 1 Engine, 3 Battery
No Selector Switch
NEW WIRE
NEW WIRE
SURE POWER
MARINE RECTIFIER
ISOLATOR
MODEL 702
SEE EXPLODED
VIEW
STARTER
CABLE
SURE POWER
MARINE RECTIFIER
ISOLATOR
MODEL 702
CIRCUIT
BREAKER
SEE EXPLODED
VIEW
STARTER
CABLE
CIRCUIT
BREAKER
+
-
+
ENG. BATTERY
ONLY
CIRCUIT
BREAKER
-
+
AUXILIARY
BATTERY
-
TO ACCESSORY
DISTRIBUTION PANEL
-
+
AUXILIARY
BATTERY #1
TO ACCESSORY
DISTRIBUTION PANEL #1
TO ACCESSORY
DISTRIBUTION PANEL 2
SEE EXPLODED
VIEW
NEW WIRE
CIRCUIT
BREAKER
SURE POWER
MARINE RECTIFIER
ISOLATOR
MODEL 702
ENGINE #1
+
-
AUXILIARY
BATTERY #2
SURE POWER MODEL 702
Application: 1 Engine, 2 Battery
with Selector Switch
SURE POWER MODEL 2703
Application: 2 Engines, 3 Battery
No Selector Switch
SEE EXPLODED
VIEW
+
ENG. BATTERY
ONLY
-
ENGINE #1
BATTERY
STARTER
CABLE
SURE POWER
MARINE RECTIFIER
ISOLATOR
MODEL 2703
NEW WIRE
CIRCUIT
BREAKER
CIRCUIT
BREAKER
BOTH
CIRCUIT
BREAKER
CIRCUIT
BREAKER
ENGINE #2
1
2
OFF
SEE EXPLODED
VIEW
+
-
+
ENGINE #2
BATTERY
-
SELECTOR
SWITCH
AUXILIARY
BATTERY
+
NEW WIRE
-
+
BATTERY
#1
TO ACCESSORY
DISTRIBUTION PANEL
BATTERY
#2
TO ACCESSORY
DISTRIBUTION PANEL
SURE POWER MODEL 2703
Application: 2 Engines, 3 Battery
with Selector Switch
CIRCUIT
BREAKER
SEE EXPLODED
VIEW
NEW WIRE
ENGINE #1
+
-
+
CIRCUIT
BREAKER
ENGINE #1
BATTERY
1
2
OFF
SELECTOR
SWITCH
STARTER CABLE
ENGINE #2
SEE EXPLODED
VIEW
+
ENGINE #2
BATTERY
AUXILIARY
BATTERY
BOTH
TO ACCESSORY
DISTRIBUTION PANEL
SURE POWER
MARINE RECTIFIER
ISOLATOR
MODEL 2703
BOTH
1
SELECTOR
SWITCH
2
OFF
CIRCUIT
BREAKER
STARTER CABLE
NEW WIRE
10189 S.W. Avery Street
LITHO IN USA
Tualatin Oregon 97062
Tel 503.692.5360
PAGE 4
Fax 503.692.9091
www.surepower.com
INSTRUCTION 180119A 0102