How to Wire a Marine Battery Switch
Battery switches are an important safety device in boats and recreational vehicles. The ability to shut off a battery in a boat can prevent dangerous attempts to start the motor in the event of a fuel leak in the engine compartment. In both boats and recreational vehicles, having a second battery to select can prevent being stranded when the main battery is discharged. Adding a battery switch is a good job for the do-it-yourself boater or RVer.
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Instructions
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1
Disconnect the negative cable from the battery.
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2
Determine the best location for the battery switch. This should be someplace easily accessed by the boat operator.
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3
Install a battery box for the second battery, if one is being installed.
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4
Measure the distance from the main battery to the switch. You will need one battery cable this length.
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5
Measure the distance from the secondary battery box to the switch. You will need another battery cable this length.
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6
Measure the distance from the secondary battery to the vehicle, or boat, ground connection. You will need a third cable of this length.
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Determine the distance from the battery switch to the terminal where the main battery's positive cable attaches to the solenoid or starter. You will need to purchase this cable also.
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8
Remove the positive cable from the main battery and solenoid or starter.
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9
Install a cable from the positive post of the main battery to terminal one of the switch.
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10
Install a cable from the positive post of the secondary battery to the switch.
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11
Install the cable from the OUT (common) terminal of the switch to the point on the solenoid or starter where the original positive cable from the main battery was attached.
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12
Attach the ground cable for the secondary battery to the battery and the chassis ground.
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13
Place the battery switch in the off position.
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14
Attach the main battery negative cable to the battery.
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15
Turn the switch knob to select a battery to use.
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Tips & Warnings
Wear safety glasses and gloves when working with batteries. Always disconnect the negative battery cable first.
Resources
- Photo Credit Photos by KK Lowell
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Comments
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That's great and everything but this bit: "Attach the ground cable for the secondary battery to the battery and the chassis ground." What chassis ground? It's a fiberglass boat..
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My lighting was poor, so I used my remote charger to boost the service battery, the result, within seconds was a short circuit and fire. The 3-way switch has been damaged and will need replacing. What may have caused this? I have charged the engine start battery in this manner on the odd occasion and everything was fine.
