We’ve all been there. You stuck your weekend car in the garage, then life happened, and now it’s been 4 months. The battery is drained because there’s some gremlin that’s draining your battery, and you didn’t know about it. Now what would have been a pleasant drive up the coast is a day spent looking for the charger you swear you had in the shed. Next time, throw a disconnect switch on your battery before you store it.
If you are looking for a disconnect switch, we put together this guide for you. We’ll talk about the basics, give you a top ten list with reviews, and follow up with some in-depth stuff. In the end, we’ll try and answer any question you’ll have and get you informed as fast as possible.
Battery Disconnect Basics
There is nothing complicated about a disconnect switch; their entire function is summed up in the name. There are some key things to keep in mind when looking for one, though. First, let’s look at some of the reasons you might install a disconnect. Knowing the application will help you determine which features you want.
Reasons to Install a Disconnect
The following are the common reasons to install an on/off switch for your battery. We’ll go more in depth in the big guide on these.
- Security: If the battery does not provide power to the starter, a would-be thief can not start the car unless they connect it.
- Battery Longevity: Disconnecting the battery before putting a car in storage will prevent the battery from discharging while in storage.
- Convenience: When you work on a car, the first step is often “disconnect the battery.” If you work on your car a lot, it can save a ton of time if all you have to do is flip a switch.
The Types of Disconnect Switch
Two main categories separate different switches from one another: where they can be installed and how they operate.
Install Location
There are two primary places you can install a disconnect switch.
- On the Terminal: Many switches attach directly to a battery terminal.
- Remote: Remote switches can be installed anywhere that you can reach. You simply run the battery cable to the switch and then to the car.
Operation Type
There are basically four different ways that a switch will work.
- Rotary: A rotary switch is very simple and is the most common type. You just turn the dial on or off.
- Screw: A screw style switch uses a knob that you unscrew to turn off. They are very simple and hard to damage.
- Key: A keyed switch needs a special key to turn the switch on or off.
- Knife: A knife, or blade, style switch is a lever that makes a connection between two contact points.
Other Considerations
There are a handful of other considerations beyond the type of switch.
- Amperage Rating: We’ll talk more about amperage below. Generally speaking, it’s not something you have to worry about unless you have extra lights, an aftermarket sound system, or a larger vehicle. 100-200 amps is sufficient for most vehicles.
- Weatherproofing: Boats, off-road vehicles, and heavy equipment should use switches that are waterproof and protected from mud.
- Price: Disconnect switches are relatively inexpensive, but some do cost quite a bit more than others. You’ll have to pay more for high amp ratings, all-metal construction for durability, and specialized designs.
- Access: Most switches will be installed near the battery, so you need to be able to get to the cables and reach the switch. If you can’t, or don’t want to have an easily accessed switch for safety reasons, there are relay-based switches that can be installed anywhere.
- Looks: It’s probably not a priority for most people, but it’s nice to have a switch that fits into the theme of your build or is high-contrast and easy to find.
That’s about it for features and qualities. When you look through our list, just note that primarily we wanted to make sure we have a good variety for you to choose from. That way, you can find the one that fits your needs the best, even if it’s not the one we think is the best.
Top 10 Car Battery Disconnect Switches 2021
1. Best Overall Switch: Kohree Battery Disconnect
Editor’s Rating:
Facts
- Install Location: Remote
- Type: Rotary Switch
- Amp Rating: 275
The Best Feature
The Kohree switch is just a simple on/off dial. Nothing really stands out about it, but it works just fine, and it’s inexpensive. It’s easy enough to mount, simple to use, and is instantly identifiable as a battery disconnect. Usually, that’s all you want.
What Could be Better
It’s all plastic, which means it won’t last as long as a metal switch. Most people don’t disconnect their batteries often, so this switch will probably last as long as your battery with no issue.
The bigger issue is that it can’t be installed flush. In fact, it’s a little awkward to install altogether. It has plastic covers that keep debris out, which is nice but adds frustration to the process.
How Does it Compare
Everything else on our list has some specialty. That means if you need something specific, there’s probably a better option. For instance, if you have a high amperage application, there’s this switch that can handle a lot more current. If you need better security, this inexpensive switch is operated by a separate key. If flush mounting is important to you, this QuickCar switch is perfect.
For most people, though, the Kohree Battery Disconnect is fine, and that’s why we recommend it.
Pros
- Inexpensive
- Easy to use
- Easy to find
Cons
- Not as durable as other switches
- Can be frustrating to mount
2. Best Budget Switch: Top Post Master Disconnect
Editor’s Rating:
Facts
- Install Location: On the terminal
- Type: Screw
- Amp Rating: 300
The Best Feature
The best thing about a screw style post mount switch like this is that they could not be easier to install. You pop the battery cable off and slip the switch onto the terminal. That makes installing these switches a very approachable project for anyone. They are also cheap, but unlike a lot of inexpensive things, they are still fairly strong.
What Could be Better
You have to mount it to the battery, which means you have to have access to the battery to use it. You also need space, although not as much as other styles of terminal mounted switches.
The only issue that you might run into is that since they are so cheap, there are inconsistencies from part to part that affect the size and shape. You may find that it’s not quite big enough to just slip onto a terminal or that the post is too big for a standard cable end. It’s nothing a tap with a rubber hammer won’t fix, but it can be annoying.
How Does it Compare
We have a right angle switch here that installs and functions identically but can help if your cable routing doesn’t allow for the extra length this switch offers. Also, if you don’t have a standard post style battery, you’ll need a remote switch or a side post switch.
You will have to spend more for just about everything else, though, even if it’s not much more. When a car part can be cheap and straightforward, it’s hard to justify spending more for a piece that performs the same.
Pros
- Inexpensive
- Simple to install
- Durable
Cons
- Won’t fit on some batteries
- Might need to be reshaped to fit your car
Editor’s Rating:
Facts
- Install Location: Remote
- Type: Rotary Dial
- Amp Rating: 250
The Best Feature
The Flaming River switch can handle 2,500 amps for short bursts. That gives it the highest amp rating on our list and makes it one of the very few switches suitable for being installed on a large battery. People with bigger trucks or huge sound systems who need a shutoff will love that.
What Could be Better
It’s the most robust switch on this list, but it’s also the most expensive. Most of the time, that won’t be an issue. If you need a switch like this, especially if you’re building some kind of competition vehicle, chances are you’ve already spent a lot more on other components.
The other issue, and it’s a really minor issue, is that it can disappear in an engine bay. The black mounting bracket and dull metal finish make it blend in with grease and bolts. It’s nothing some red paint can’t fix, but most other switches on this list are already high-contrast and easy to find.
How Does it Compare
The Blue Sea Systems switch is also an all-metal, waterproof, and high-current switch. Unless you really need the extra amp rating that this switch offers, the Blue Sea Systems switch will work just fine and save you a lot of cash.
Pros
- Waterproof
- Heavy-duty
- High amp rating
Cons
- Very expensive
- It’s probably more than you need
4. Waterproof High-Current Switch: Blue Sea Systems
Editor’s Rating:
Facts
- Install Location: Remote
- Type: Rotary Switch
- Amp Rating: 350
The Best Feature
It’s indestructible, has a high amp rating, and can be installed anywhere. If you have an RV or boat that has batteries in need of isolation, this is perfect. It’s especially good for RVs since it’s rated to 48v. A battery bank with 4 batteries can all be hooked to this single switch.
What Could be Better
It is a bit expensive. That’s because it’s made of metal and has beefy internal parts, which means that the quality is worth the price. It just is rather expensive for what amounts to a fancy light switch.
It’s also not the most intuitive thing to mount. It has four holes through the case that you can run a bolt through, but if you are going to install it on a dash, it’ll protrude awkwardly, or you’ll have to source out a faceplate for it.
How Does it Compare
This switch sits comfortably between the Flaming River switch and the Kohree switch. It has a much higher amp rating than the Kohree but has a higher price to match. If you just need a simple switch for your car or RV and don’t need the extra durability or heft, the Kohree might suit you better.
On the other hand, if you have a race car and need something even more robust, the Flaming River switch is what you need.
If you have a boat, though, we consider this your best option. Even though the Kohree is technically rated for marine applications, you are going to want the extra quality that this switch offers. It’s one thing to be stuck on the highway waiting for a tow truck. It’s a whole new level of frustration rowing a large boat back to a dock.
Pros
- Well-made
- High amp rating
- Waterproof
Cons
- A little expensive for a switch
- Can be hard to mount
5. Best Relay Switch: Stinger SGP38
Editor’s Rating:
Facts
- Install Location: Remote
- Type: Relay
- Amp Rating: 80
The Best Feature
Most switches have to be installed near the battery because it’s difficult to run the heavy cables needed. A relay controlled switch solves that issue because you can install the body close to the battery but operate it using a switch mounted anywhere.
The biggest reason to use something like this is that it makes for excellent theft protection. You hide the on/off switch somewhere in your cabin, like under a cup holder or behind a false panel. When you park in a bad area, you flip the switch. That way, even if some loser manages to get into your car, they can’t hotwire it since the battery is disconnected.
What Could be Better
The amp rating is fairly low, which is unfortunate. If you are isolating a secondary battery or just interrupting a solenoid signal for anti-theft, it’s fine. It’s going to break if you try to use it as a main cut-off for your entire system.
How Does it Compare
If you compare this switch to a dedicated disconnect like the Blue Sea switch, you’ll find a lot to complain about. The Blue Sea switch is waterproof, can handle a large amount of current, and is incredibly durable. This Stinger switch is none of those things.
All that really means is that you have to do a lot more thinking and prep to best utilize this relay switch. If you want something similar but a bit easier to use, check out the wireless relay switch. It’s more complicated, but you can operate it from anywhere.
Pros
- The switch doesn’t need to be near the battery
- Good for theft protection
- Easy to operate
Cons
- Has a low amp rating
- Is more complicated to install
6. Easy Access Switch: Zoostliss Battery Disconnect
Editor’s Rating:
Facts
- Install Location: Remote
- Type: Rotary Switch
- Amp Rating: 500
The Best Feature
There are two neat things about this switch, and both lend themselves well for using this switch on smaller, non-car things. The first thing is that it’s easy to mount anywhere since it’s really compact and designed to be externally mounted. The second thing is that it’s operated using a removable key, so if you don’t want someone to use your lawnmower when you aren’t home, you can just leave with the key.
What Could be Better
The quality could be better. That’s something that’s expected from a cheaper product, but it’s worth saying.
The other issue is that you can lose the key. The key is on the big side and awkwardly shaped, so it is not something you can just thread onto your keychain and forget about. Chances are you’ll throw it into a toolbox where it will get lost in a sea of sockets, and then you’ll go to try and dump your trailer of dirt and won’t be able to find it.
How Does it Compare
The Zootliss switch here is low in cost, which lets it compete against the screw style switches. That means if you don’t want a terminal mounted disconnect and are on a budget, this is the best option we list.
However, the Top Post Master switch, or a more expensive switch like the one by QuickCar, will serve you better if you want a disconnect for your primary vehicle. Neither will leave you stranded if you lose the key, and both are of higher quality.
Pros
- Inexpensive
- Secure
- Easy to install
Cons
- Quality could be better
- If you lose the keys, you’re out of luck
7. Great Looking: QuickCar Racing Products 55-010
Editor’s Rating:
Facts
- Install Location: Remote
- Type: Rotary Dial
- Amp Rating: 125
The Best Feature
This switch isn’t unique in operation or function, but it is unique in the fact that it looks like it fits in a high-performance dash. It has a mounting plate that is more familiar than the standoffs that many switches use, and the high contrast red on black color scheme fits right into the racecar motif.
What Could be Better
There’s nothing really wrong with it, but there’s a lot of little areas that could be improved. It’s not as protected as other switches, so a little bit of shielding and waterproofing would go a long way to improve the design.
It would also really benefit from a higher amp rating. It’s fine for your dirt oval car that has a total of 3 wires, but the minute you add radios, lights, and beefy ignition systems you’ll reach the limit of what this switch can handle.
How Does it Compare
If you are considering this disconnect, you are looking for something that fits your high-performance car. There are two other switches on our list that are meant to be used as safety disconnects on race cars or similar: the Flaming River switch and the Blue Sea Systems switch.
Both are more expensive than this QuickCar switch, but both can handle a lot more amperage. If you have a truck or something that will get covered in mud, the Blue Sea switch is waterproof. If you have a car that has a really serious electrical system and can pull over 1,000 CCA, get the Flaming River switch. If you have a race car on a budget or a restomod that has to look good, the QuickCar is perfect.
Pros
- Looks good
- Has a standard mounting plate
- Is inexpensive for its category
Cons
- The amp rating isn’t very high
- It isn’t waterproof
8. Wireless Remote Switch: WATERWICH 12V
Editor’s Rating:
Facts
- Install Location: Remote
- Type: Wireless Relay
- Amp Rating: 180
The Best Feature
The best and defining feature of this shutoff switch is that it’s controlled by a key fob. That means you get out of your car, hit the keychain, and the battery is disconnected. If anti-theft is what you want most out of a disconnect switch, this is your best option.
What Could be Better
We wish it was easier to install. That’s what’s going to turn most people off when it comes to this device. Unlike a traditional switch that just needs one input and one output, a wireless remote switch needs constant power. That adds a layer of complexity and another failure point to the electrical system.
How Does it Compare
If you don’t value the ability to disconnect the battery from outside the car using the wireless transmitter, then there’s really no reason to get this switch. A standard relay switch like the Stinger is still great for anti-theft, and almost any rotary switch will be more reliable over time.
One of the smaller things to consider is that it’s actually easier to fit into an engine bay despite being more complicated to install. Most remote switches still have to be accessed; you need to be able to reach in and flip the switch. With a relay switch, you don’t have to be able to reach it. You can hide it underneath the battery without any issue, meaning that even if thieves can jimmy your hood open, they’ll need time and tools to take your ride.
Pros
- Can be operated outside the car
- Great for theft protection
- Can be installed in places with low access
Cons
- Is more complicated than other switches
- Not as reliable as other switches
9. Decent Side Post Switch: Abigail Disconnect
Editor’s Rating:
Facts
- Install Location: On the terminal
- Type: Knife
- Amp Rating: 250
The Best Feature
The greatest thing about a knife-style disconnect is that they are incredibly simple and easy to understand. It’s just a bar of metal that is either making a connection or not.
What that’s best for is for people who do a lot of work on their vehicle and will be connecting or disconnecting the battery often. You can flip it off, make a change, then flip it on without needing to spend a ton on a high amperage rotary switch.
What Could be Better
There are a few big disadvantages to the knife-style design. The most significant problem is that it has a ton of exposed copper, so you absolutely should not use it on the positive terminal.
That leads to the second issue, which is that it has to be installed on the side of the battery. It takes up a lot of room, so if you are cramped for space in the engine bay, it’s a terrible option.
How Does it Compare
For most people, something like the Top Post Master switch is a better option because that style of terminal is more common, and that style of switch is more secure. However, if you have screw style terminals, which are really common in GM vehicles, then you can’t use the Top Post Master switch. That leaves a remote switch or something that can mount to the side of the battery like this knife switch.
Pros
- Mounts to bolt in style battery terminals
- Very easy to operate
- Easy to install
Cons
- Only fits a certain battery type
- Takes up a bit of space compared to others
10. Alternative Budget Switch: GraceMe Right Angle
Editor’s Rating:
Facts
- Install Location: On the terminal
- Type: Screw
- Amp Rating: 150
The Best Feature
This switch sits at an angle so that you have extra options when connecting the cable to the terminal. That’s especially useful if you have short cable or are worried about clearances.
What Could be Better
Screw style switches that mount to a terminal sufferer from the same handful of issues. The screw is a bit more prone to failure than a rotary dial is, and if you are unlucky, it’s easy to lose the screw if you take it all the way off.
The bigger problem, and it’s one that affects every post style terminal connection, is that it only works with a specific size of terminal post. If you have screw in terminals or want to install the disconnect on something that isn’t a car, you are out of luck.
How Does it Compare
It installs and functions identically to the Top Post Master switch; it just has a different configuration. It’s still cheap, it’s easy to install and easy to use. If you don’t want something hanging off a terminal, get the inexpensive Zoostliss switch instead. For 90% of applications, this switch or the Top Post Master switch will be just fine.
Pros
- Easy to install
- Easy to use
- Inexpensive
Cons
- Only fits one type of battery
- Has to be mounted on the battery
A Closer Look at Disconnects
We said above that we’d get into some of the specifics. We would hate to be liars, so here we go. We will start with expanding on the different uses for a disconnect switch.
Uses for a Disconnect Switch
We mentioned it before, but the most significant factor when choosing a switch for yourself is what you are going to do with it.
Race Car Safety
Many sanctioned race bodies require a battery shutoff. You’ll have to check with the rules for whatever event you are participating in. Be aware that sometimes safety tech wants the switch on the positive side.
Anti-Theft
The general idea behind using a battery disconnect for anti-theft is that a thief can’t start the car and drive away if they have no power. The downside is that most disconnect switches are designed to be easy to get to, which means that the thief will be able to simply turn them back on.
If you are looking for anti-theft from a switch, get one that either has a hidden switch that activates a relay or that uses a key. That way, even if a thief can get your hood open, they can’t simply hook the power back up.
Storage
You should generally disconnect your car’s, boat’s, or lawnmower’s battery before putting it into long-term storage. Most vehicles will have some parasitic loss. That loss comes from small devices or wiring issues that draw a tiny amount of energy from the battery. It may take those small leaks months to lower the voltage significantly, but they can kill a battery if left too long.
If you are storing something with a battery long-term, consider picking up a battery maintainer as well. We have an entire article about them over here.
Battery Isolation
RVs, some trucks, and cars with aftermarket sound systems will often run multiple batteries. Some people will even install extra batteries to help run inverters and similar things. By isolating the batteries, you can control how they charge and what they are used for.
While this is a common reason, you should consider using a battery isolator instead of or in addition to a disconnect. You can brush up on what those do here.
Convenience
Whenever you work on a car, you should remove the negative battery cable. Popular Mechanics has a good breakdown of why, including a mildly terrifying anecdote. If you do a lot of work on your car, or need to diagnose electrical problems, having a simple disconnect switch will save you a ton of time and frustration.
About Amperage
Amperage ratings can cause a little bit of confusion. Your battery is measured by the Cold Cranking Amps it can produce. That’s the amount of current the battery can produce for a very brief period of time to start the car.
A switch will have a similar rating in terms of the maximum amperage. However, that information can be hard to find or inaccurate. The general amp rating is more accurate and easier to find on the switch. It’s a much more difficult number to derive from your car, though, which makes matching a switch to your electrical system frustrating.
Adding Up the Accessories
A very basic electrical system only has an amp draw of 50-100 amps, which means that every switch on our list is sufficient. In order to find out whether or not you need a high-current switch, you need to look at all the things attached to your battery. Start with 80, then add:
- +5 amps per extra light
- +100 for a high-performance or larger engine (5 liter+ or diesel truck)
- +20 for small subwoofer and amp
- +50 for a larger aftermarket sound system
- +20 for a small inverter
- +100 for a large inverter
If you want to be more precise, you need to calculate the total wattage of all your accessories and divide that number by 12. Then add that number to the output of your alternator, and then give yourself a 5% margin of error. The truth is, though, the worst-case scenario is that you break your switch and are out a few dollars.
Installation Tips
Once you get your new disconnect switch, you have to install it. Keep the following tips in mind.
- Use the right cable size. If you are installing the switch far away from the battery, you may need a larger diameter cable. Use this simple calculator to find out the wire size.
- Beware of objects that can short out the switch. Especially if the switch is a blade or screw that is exposed, and extra especially if you are installing the switch on the positive or hot side of the battery.
- Be aware that many batteries have multiple wires for each terminal. The disconnect will not work unless you sever the connection entirely.
- If a battery disconnect is getting very hot, there is an issue. Disconnect the battery asap and look for shorts/double-check your amperages.
- A battery disconnect switch is not an engine kill switch. It cannot be used in place of one.
FAQ
What Does A Battery Disconnect Switch Do?
As the name suggests, a battery disconnect switch is a device that breaks the connection between the car battery and the rest of the car. They are used for a variety of reasons, including anti-theft, safety, diagnosis, and to avoid loss of charge over time.
Should The Disconnect Be On The Positive Or Negative Side?
Most of the time, you should install a disconnect switch on the negative terminal. However, there are some situations that it’s better to install on the positive side. Multiple battery setups often have multiple grounds, so you have to use the single positive wire as the disconnect spot. Also, if you are drag racing, they often require the disconnect to be on the positive side.
Can A Battery Disconnect Switch Go Bad?
Yes, although it’s rare. Anything that has moving parts will wear out eventually. The good news is that if a disconnect switch fails, there is very little risk to your engine.
Where Are Battery Disconnect Switches Installed?
Most inexpensive disconnect switches are installed directly onto the battery terminal. Fancier switches can be remote and installed anywhere. They will often need to remain close to the battery due to factors like wire size and space, but there’s no rule that says you must do that.
Why Is It Better To Disconnect The Negative Cable?
The reason you put the disconnect on the negative side, as well as the reason you disconnect the negative side when working on the car, is that it lowers the risk of shorting out the system. The entire car is connected to the negative side through the ground, so if you accidentally touch the negative terminal to a part of the car nothing will happen. If you accidentally touch the positive side to the car, though, you will get sparks and risk damaging components.
Wrapping Up
Whether you are looking for convenience or peace of mind, a battery switch is a simple solution to many battery-related issues. If you have three minutes, a crescent wrench, and enough money to buy lunch, then you have everything you need to install a disconnect. Grab one and avoid the frustration of a dead battery.
Source: Tools - autoquarterly.com
