A Battery disconnect switch is a device that acts as a physical current cut off switch for a battery. It is attached to the negative terminal of a battery and will have a lever or screw-like switch for quick battery current termination. It is the mechanical equivalent of untying a battery terminal with a spanner so that the battery is isolated completely from the car or other electrical connections.
What other names is a battery disconnect switch called?
There are different names that people call this simple yet incredible innovation.
Some call it isolator switch, battery disconnector, battery isolator, or the longer and more professional term battery disconnect switch. So if you see any of these names on the specifications know there are all talking about the same thing.
Why do I need a disconnect switch?
If you are planning of storing away your car or boat for a very long time or you don’t frequently use it, having a disconnect switch will be your lifesaver. If you don’t frequently use your car, RV, or boat background electronics will gradually drain your battery and cause it to fail on you when you want to have a ride next time.
You need a battery disconnect switch so that you can easily cut out your battery from the background electronic activity to prevent your battery from draining.
If you live in very cold places a battery isolator will prevent your battery from failing to start when you want to use it after a while in freezing temperatures.
Security is another reason you may want to get yourself one of these. When you use battery switches you can prevent some amateur unauthorized use or total theft of your vehicle. Of course, a professional car thief will easily overcome this hurdle. But not all people that want to steal your car will be experts and a battery switch maybe your savor on that day.
The other reason you may want this device is to preserve the battery charge of your second battery. There are several reasons you may have two batteries install such as powerful audio load. In such cases, a battery switch will protect the power in your second battery from draining.
Battery disconnect switches are very affordable and will not make any serious dent in your wallet, averaging at $20 for simple designs. It’s worth it to get you one of these for the benefits it offers, it’s so affordable.
And if you have a special car that you drive only once in a while and you have naughty boys at home, you may want to do more than just hide the keys but have a switch that will stop them from taking off even when they find the keys.
Types of Battery Disconnect Switches available on the market
There are three types of battery disconnect switches. And these are the knife blade, knob-style, and the keyed and rotary type.
The knife blade type is named after the fact that it’s shaped like a knife. Its blade-like shape makes it easier for it to fit in situations where clearance from the body of the bonnet is a problem and the space is tight between the battery terminals and the body of your hood. This type is very simple and very easy to install either vertically or horizontally depending on your clearance.
The second type, the knob style is by far the most popular type. It has an intuitive clockwise or counterclockwise knob, hence the name, switch to cut off or supply battery power effortlessly. These switches are miniature and able to fit in tight spots. It is also connected directly to the battery terminal and does take any special equipment or expertise so anyone can install it.
The last type is the keyed and rotary type that uses a key or rotary to turn it on and off. A key makes for added security. Its security features make this type the most commonly used in industrial and other corporate settings. There are also used in boats, RV, and agro machinery.
How to connect a disconnect switch
Connecting a battery disconnect switch is a very easy procedure that almost anyone can do without paying a mechanic.
As a precaution, you want to make sure you have a pair of gloves and a set of goggles when handling your battery. Accidental acid spills will lead to severe injuries and slash liquid in your eyes.
Having covered your personal safety, you need to switch off your car engine and electronics completely and use the right size spanner to remove your negative battery terminal. Depending on your particular model connect one side of your battery switch to the battery terminal directly and the cord that came to the terminal must be connected to the other side of your switch. With that done you are pretty much ready to go.
Similar post: Best Car Alarms For Vandalism
Pay close attention to the space you have available in your car hood as that may affect the clearance from the body of your car.
Price ranges for switches
For all the benefits it offers, the cost of a battery switch is always within reach for many car owners. You can get yourself one of these, starting from as low as $20. The more advanced models will cost a bit more for extra features but a simple one will suffice if you on a tight budget. I think everyone should most certainly have a Battery Disconnect Switch.
Important features to consider when buying a Battery Disconnect Switch
The most important feature of a battery isolator is its amperage. The amps refer to the maximum current it can handle without shorting and getting damaged. You need to make sure you get a switch with the right amps. Placing a smaller rate switch on a powerful heavy-duty alternator and or battery will be dangerous. And just as a good precaution you should always get a battery switch with higher but not equal amps to your car and battery system.
Switch Design and hood space
You want to pay close attention to both the design of your switch and space in your car hood, RV, or boat. You want to make sure that the clearance from the body of your hood is enough to allow the switch not to touch the body.
How you are going to install and fit the switch to your battery must be carefully considered. Some battery disconnect switches are very complicated and may need you to make some mounting changes to your existing battery so that they can fit. An amateur should avoid such switches because you easily fail to get it right and even endanger your car safety in doing so. It will also likely cost you more to do so.
Best Battery Disconnect Switches of 2021 Reviewed
Now that we have run you through all the essentials of battery disconnect switches, here is our recommended and reliable list of some of the best battery disconnect switches.
Fastonix 2 Post High Current Master Battery Disconnect Switch with Wace Plate
- Rated 180A continuous
- 3/4 inch hole of mounting
- 3.52 ounces of weight
- 3/8 terminal post.
The Fastonix 2 Post High Current Master Battery Disconnect Switch is a universal disconnect switch that works on any car battery. People have different reasons for using a disconnect switch in their cars and how the disconnect switches are connected matters. This disconnect switch must be connected on the negative if you are trying to shut off the battery. On the other hand, put it on the positive if you are doing it for NHRA compliance.
The Fastonix 2 is a manually operated disconnect switch. This means that it cannot return to the off position automatically. Not until you turn the actuator, the Fastonix 2 will remain in the same position. On a positive note, this feature will help prevent your car from being stolen.
The Fastonix 2 also has two mounting configurations. The first one is the thin panel which has a maximum thickness of 1/4 inch and the second is the thick panel with a maximum thickness of 5/8 inch. The disconnect switch has a threaded shaft. The threaded shaft is where the switch will be mounted with two nuts for precise positioning.
This model can be mounted anywhere. But to avoid incidental shorting, you are advised to mount this switch as close to the battery as possible. The gauge wire easily hooks it up if it’s close to the battery.
It is also equipped with a heavy-duty handle. This handle is at an off position when packed. The reason for this is to prevent the incidental switching of the disconnect switch. So when you are turning the switch to the on position, it gives a solid click. In this way, you will be able to know if you disconnect switch is on or off.
Sometimes we drive through unfriendly environments and the major function of the heavy-duty casing is to protect the internal components of the switch. However, this model is designed with the terminals being exposed outside the body, so you are advised to put them inside if you are mounting the switch lever on the outside.
They are also designed with two small terminals. The function of these two terminals is to switch off the smaller load of power. In motor racing, the disconnect switch is where the ignition power wire is run through so that the sports car can be turned off when the disconnect switch is off. Among the two terminals, you use the smaller terminal to switch any load that is not more than 20 amps.
Even though the current rating of this disconnect switch is 12V, it can also work on a 24V system. But this is only possible if the amperage of the application is low. A 160 track hoe is a good example of a 24V application that the Fastonix 2 battery disconnect switch can work on.
Also, this type of switch works well as a power disconnect for RVs when they are not being used.
The RoadMaster 766 Remote Battery Disconnect is an excellent system. But before installing this model, you are advised to conduct careful system planning. This model unit can be used to disconnect a battery while towing your car. The steering column lock doesn’t engage if the battery has been disconnected. If you use this model undertow, you need an extra fused power supply from the battery to power up the braking of the car. With this feature, you can also be charging your battery while towing your car.
The RoadMaster 766 accommodates both the air force one and the brake buddy system. For the Air Force One system, a dedicated power supply must be provided. You attain that by crimping a fuse wire to an extra ring terminal on the solenoid body. You will find this extra terminal under the battery post. During this process, the Air Force One system will remain powered up when other systems are shut.
On the other hand, to power up the brake buddy system, you will need to connect an appropriate size of a fuse with a wire direct from the battery. This can be done in two ways. The first one is adding an extra power port under the dash and the second is by simply wiring an already existing power port to the battery. The second option can be done without tapping from the fuse block.
The RoadMaster 766 is designed to disconnect the positive side of your battery. In this model, both the brake light switch and the supplemental brake system are directly hooked up to the positive side of the battery. Before the battery disconnect connection is done, the supplemental power source must be connected directly to the positive side of the battery. The negative side is only used for blade disconnect but unfortunately, this doesn’t work on some car models.
The RoadMaster 766 is also easy to install. To avoid accidental contact, the on and off button of this unit is easily canceled in the kick panel. You are advised to install it next to the battery for the battery cables to easily hook it up. The manufacturer of this model has taken an extra mile by pre-assembling it for easy installation.
WirthCo 20148 Battery Doctor Battery Disconnect
- 12 volts
- 2-1/4 inch
- Vertical style
- Stud and wing nut top post terminal
The WirthCo 20148 is a high-quality product with the power of 250 amps continuous and 750 of surge. This is the maximum rating of amps it can handle in case you want to use it on a multiple battery power bank. This means that this model can be used on a 5th wheel trailer with a 12V system.
When disconnecting the battery, the WirthCo 20148 is perfect for mounting on the negative side. Mounting this model on the positive side will create a short because it has a lot of exposed metal. It would also not be easy to connect on the positive side because both the connector and the post are on the negative side. In addition to that, on any DC system, it is best to cut power from the negative side and this model is designed for that.
On the downside, this model only works on batteries that have top posts. Where the lever pivots vertically it’s where the positive battery cable and the battery post connects. On the opposite side, the lever must not be pressed into the receptacle. On the WirthCo 20148 model, the lever does not move horizontally.
This model lasts longer than most of the ones on the market. It is made from brass; therefore, you are advised to be using dielectric grease to prevent rusting. It’s only the bolts and the wing nuts that are stainless.
It also easily fit during installation. The WirthCo 20148 will fit the negative side of any battery as long as it’s a 12V. On the other hand, the post on the blade switch easily accommodates the negative clamp without any difficulties. The knife blade rotates more than 180 degrees to the parallel open position. This brings about the best of life extension of the battery.
It’s a multi-compatible device. It works on cars, boats, campers, and other applications of power disconnect. You can use two of these models on a 3/4 snow plow truck and they will work perfectly fine. On the downside, the WirthCo 20148 model only works on an upright post.
Perko 9611 DP Compact Medium Main Battery
- High conductive studs
- Polycarbonate body
- 315 amps continuous
- 50 volts
- Weighs about 13 ounces
The Perko 9611 is an on and off battery switch that uses the Perko traditional footprint of the 9601 series. This means that they are easy to install. The Perko 9611 battery switches can be mounted in different positions. And the fact that they are protected from ignition; they can be installed in engine rooms of equipment’s powered by gasoline.
The Perko 9611 series is designed for surface mounting. They are a compact disconnect type of switches. Meaning they have a bright red polycarbonate reinforced housing for safety. The reinforced housing has large easy to turn knobs. Red fiber-reinforced polycarbonate is for heavy-duty switches.
The additional features of the Perko 9611 series include key lock security and alternator disconnect. Four removable skirt panels have been installed in this model. They are for easy cable connection from different directions. They are equipped with high conductivity studs that are long enough to handle more than one cable. These high conductivity studs are also strong enough for torque needed to secure connections.
The Perko 9611 series helps manage the overall electrical use of power onboard. And during a period of inactivity, the Perko 9611 series helps to prevent the battery from draining. In a case of an emergency, they allow for a quick and easy way to shut down the entire electrical system. And to prevent unauthorized use of your car, an optional key lock has been installed.
Blue Sea 6006 M series master battery switch
- intermittent rating of 500A
- Single circuit
- Alternator field disconnect
The Blue Sea 6006 M series is a single circuit type of disconnect switch.it is equipped with an alternator field disconnect (AFD). The function of alternator field disconnect is to protect the diode in the alternator in the event of the switch being switched to the off position while the engine is running.
An LED can be connected to the alternator field disconnect terminals to indicate if the battery switch is in any position but off. But this can be applied if alternator field disconnect is not being used to protect the alternator. The Blue Sea 6006 has a maximum voltage capacity of 48V DC. It will not work on any appliance that has a higher rate. It’s designed with a stud size of 3/8 inch. On the other hand, the terminal stud torque is 120 in-ib (13.56 Nm). These features make the Blue Sea 6006 M series easy to install at any position.
The Blue Sea 6006 M series has an intermittent rating of 500A (5 minutes). Intermittent rating refers to the maximum amount of current a switch is designed to carry for a minimum of a designated period. This maximum current of the switch is designed to be conducted for countless periods. It also has a cranking rate of 30 seconds. This refers to the cranking current which is required by the starter circuit before the engine start. During the starting circle, the starting current varies significantly. And to overcome the inertia and compression of the engine, a large surge of current is required.
When the surge occurs, the current becomes two to four times the average cranking current. There are peaks and valleys as the engine turns. This happens as the pistons are going through the compression and exhaust cycles. The sizing up of the batteries, cables, and battery switches is done by the cranking current. The Blue Sea 6006 M series is ignition protected. This means that it’s safe to install it on a gasoline-powered car.
Longacre 45761 battery disconnect switch with panel 2 terminal
- Bright red handle
- 175 amp of continuous rating
- Aluminum panel
The Longacre brand has built a reputation for itself in the marketing of gauges, scales, and battery switches. And the Longacre 45761 battery disconnect switch with panel 2 terminal is one of their designs. So If your car battery has drained, this is the easiest and practical solution to the problem. There are different ways in which Longacre 45761 can be installed. Creating a break in the negative cable of the battery is essentially what you are doing. The positive cable of the battery is for a starter while the negative cable for a frame.
For installation, you are required to have two black negative cables. 42-inch cables are a recommended length for a perfect installation. So be sure to measure before installation. Get one of the black cables and hook it up to the battery. The other end of the cable must attach to the kill switch. Then get the second cable and hook it up to the kill switch. The loose end of the second cable must be attached to the frame. If you don’t have enough port you may need to drill holes in the firewall.
This model of a switch does not require grounding. You are advised to put it in a place like a ground wire. You can also put it in the hot wire but you will be required to pay extra attention to avoid grounding it accidentally.
The handle of the Longacre 45761 is red in color and removable. Through the center, the handle is secured by a Philips head screw. And to remove the handle, the screw must first be removed. Once the screws are removed, the handle can be turned with a pair of pliers. The Longacre 45761 has studs of 3/8 inch in diameter for easy mounting. A solid sheet is the most preferable place for mounting the Longacre 45761.
The Longacre 45761 can be mounted anywhere. But to avoid incidental shorting, you are advised to mount this switch as close to the battery as possible. The gauge wire easily hooks it up if it’s close to the battery.
The Longacre 45761 has a heavy-duty casing. The major function of the heavy-duty casing is to protect the internal components of the switch. So when we drive through hostile weather conditions; this model is designed with the terminals being exposed outside the body, so you are advised to put them inside if you are mounting the switch lever on the outside.
Wrapping it up
A battery disconnect switch is a cheap and effective way to prevent your car, boat, or other batteries from totally draining so that you always have power in it when you want to use it. It is also a fantastic tool for preventing theft and other unauthorized use of your car.
Read also: Best Car Battery Testers
The fact that they are so cheap I feel every car, boat, or RV owner, among others, should have one.
1. Why does my battery still drain even when my car engine is off and no lights are on?
A lot of people think that the fact that the car is off and no lights are on that their battery is not in use. They forget the background electronics such as alarm systems and clocks that slowly and continuously use your battery power. If your car is left dormant for a long time the charge loses accumulate to a point that your battery may even drain. This is made worse if the battery is not strong and has some years on its clock already.