How to Attach a Car Battery Cut off Switch

Last Updated: October 10, 2022 References

Whether you’re going to be away from your automobile, boat, RV, or farm machinery, or if you are simply want to deter would-be thieves, a battery cutoff switch can be very useful.

Disconnecting the battery when leaving your vehicle for an extended period helps keep it from draining. When it’s time to power up, simply engage the switch, reconnecting the battery, and away you go. The opposite holds true for the larcenous types. By disconnecting the battery, you provide one more major obstacle for them to overcome before they take to the road. In your car!

Steps

1
Installing your own cutoff switch is relatively easy, but please heed the cautions outlined below. If you are skittish about playing with electricity, or not sure how to continue, consult a professional. They’ll be glad to help, and you’ll get a first-rate, firsthand education from a professional.
2
A cutoff switch is installed on or near the battery, and is used primarily to prevent battery charge depletion and for long-term storage. A fused switch will maintain current to your alarm, on-board computer, central locking system, and stereo, but still prevent your car from starting - the current generated when attempting to start the vehicle will blow the fuse and shut down all electrical connections.^{[1]
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3
Buy a new switch. The easiest type of switch you can use is a simple terminal disconnect switch. Be sure your new switch is rated to handle the load of your vehicle’s battery. This is very important! Choosing a switch that is used, worn, or underrated can result in serious electrical problems or even fire.
4
Disconnect the negative terminal (usually black, marked with a “—” sign). Do this first to avoid the possibility of electrical short circuiting or shock, neither of which are good for your vehicle or your body!^{[2]
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5
Disconnect the positive battery terminal (usually red, and marked with a “+” sign).^{[3]
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6
Carefully remove the battery clamp from the negative lead and save it should you want to remove your cutoff switch later.
7
Clean your terminals and check the fluid levels in your battery.^{[4]
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8
Attach the battery cutoff switch to the negative terminal, and tighten securely.^{[5]
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9
Reattach the positive lead to the positive battery terminal, and tighten securely.
10
Following the instructions that come with your switch, reattach the negative lead to the switch, and tighten securely.
11
Make sure the cutoff switch is turned off. Test the system by starting your vehicle.
12
If all is works as expected, turn off the vehicle and engage the cutoff switch. Make sure you still have power to all systems.
13
Do not attempt to start your vehicle with the cutoff switch engaged, or you will blow the fuse.

Community Q&A

Question

Where would the cut off switch be on a 2010 Gallant?

Community Answer

Wherever you put it. I suggest on the battery, as displayed in the article. No car comes with them installed.

Warnings

This technique will also work for carburetor icing (if you happen to still have a carburetor) but should not be tried by the timid. A better solution (prevention) is to use gas line antifreeze and not run on the dregs of a gas tank in winter.

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Be careful of any new installation that requires splicing of wires. Any sloppy connections can result in a short. As a matter of precaution, always install a fuse as well.

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If you are going to be away from your car for a major part of a northern winter, remove the battery from the car and store it out of the cold. A charged lead-acid battery will not freeze. However, a discharged lead-acid battery (and a lead acid battery will gradually discharge if the vehicle is not run) will freeze and probably destroy the battery.

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Additionally, if a car battery will not start a car during very cold weather, removing the battery to a warm place will rejuvenate it to the point where it will probably start the car. The warming takes time and the battery will need to be replaced anyway (unless you move south or wait for spring), but this may get you out of a jam if you have the patience to wait for the warming.

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