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How to Get 12V Power From Trailer Plug?

How to Get 12V Power From Trailer Plug?

If you’re someone who frequently uses a trailer, you’re likely familiar with the electrical connections found at the back of the tow vehicle. While these connections are primarily used to power the trailer’s lights, did you know that they can also provide a 12V power source? This is a particularly useful feature for anyone who needs to charge a phone, power a small device, or use interior trailer lighting while on the road. But how do you get 12V power from your trailer plug? In this blog post, we’ll explore the steps involved and provide some tips for making this process as smooth as possible.

Checking The Voltage On Trailer Plug

If you own a trailer, you know the importance of maintaining it for safe and smooth traveling. One crucial part of trailer maintenance is checking the voltage on the trailer plug. The voltage ensures that the trailer lights work correctly and signals to drivers behind you that you are braking or turning.

Step 1. Get your tools ready

Before starting, ensure you have all the necessary tools to check the voltage on your trailer plug. You’ll need a voltmeter, safety glasses, and a pair of gloves to protect your hands. You should also ensure your trailer is not connected to your car and the battery power is off.

Get your tools ready

Step 2. Check the pins on the trailer plug

Most trailer plugs have four to seven pins that connect the wires to operate your trailer’s lighting system. Begin by examining the pins on your trailer plug for any signs of damage, dirt, or corrosion. You can use a wire brush to clean the pins.

Step 3. Turn on the battery and check voltage

After examining the pins, turn your trailer’s battery power on. Gently insert the volt meter’s positive end into one of the pins on the trailer plug and the negative end onto the tow vehicle. It’s best to check the voltage on all the pins to see if there are any discrepancies.

Step 4. Interpret the voltage measurement

The voltage on each pin should vary slightly, ranging between 10-14 volts. If you notice any readings outside of this range, it may indicate a problem on the trailer lighting system. A voltage lower than 10 volts may indicate a broken wire, fuse, or bad connection, while a voltage above 14 volts may signal excessive voltage from your vehicle.

Step 5. Fixing the problem

If you notice any of the discrepancies mentioned above, start by checking if the light bulb is working correctly. Check the connection, fuses, and wires. You can use a multimeter circuit tester to ensure there’s no loose connection or a blown fuse. You can also get a professional to check out the issue.

Maintaining your trailer’s electrical system is an essential part of trailer maintenance. Checking the voltage on your trailer plug ensures that the lights work correctly, and other drivers can safely share the road with you. Regular voltage checks can also prevent accidents and save you from emergency repair bills. We hope this guide helps and allows you to keep your trailer in good working condition.

Fixing the problem

12V Power: What It Is And When It Is Needed

Do you often wonder what 12V power refers to and when it is needed? You’re not alone! For people who are not tech-savvy, the term “12V power” may sound confusing. But, it doesn’t have to be! Here we will explain what 12V power means, its uses, and when it is needed. So, let’s dive in and make things clearer.

First things first, what is 12V power? To put it simply, it refers to the amount of voltage that powers devices, appliances, and tools that operate on a 12-volt source of energy. This includes the battery in your car, a portable air compressor, or a power drill. Devices that require only a small amount of energy to function, such as some lamps and LED lights, or USB-powered devices, also work on this voltage.

Now, when is 12V power needed? The quick answer is, 12V power is required whenever a device, appliance, or tool uses this voltage rating as their power source. Vehicles like cars, trucks, and motorcycles, use 12V power to start the engine, power the headlights, and run various other functions. Similarly, RVs, boats, and campers use 12V power to keep the water pumps running, charge phones and laptops, and power various electronic devices. [1]

Moreover, 12V power is essential when it comes to camping and hiking. Portable solar panels equipped with 12V batteries can provide power to camping gear such as tents, lights, fans, and cooking appliances. The same goes for hiking. A portable fan or a phone charger can transform your outdoor adventure.

12V power is also used in the film industry to power all sorts of lighting equipment. LED and tungsten lights typically run on 12V power so that they can be used on location with a minimum need for adaptors or generators. It’s an efficient and easy way to bring the power to the set.

12V power is a versatile source of energy that powers many devices, appliances, and tools. It’s used in various applications, from the home to the wilderness, camping, and the film industry, and everywhere in between. So, if you’re planning on going on a camping or hiking adventure, or you’re involved in the film industry, or you simply have a device that requires 12V power, it’s essential to know how it works. Understanding that 12V power is simply the amount of voltage being used, and when it is needed, can make all the difference.

How to Get 12V Power From Trailer Plug: TOP Ways

When it comes to getting power from your trailer plug, it is not always as straightforward as it might seem. If you are unfamiliar with the process, you might be asking yourself how to get 12V power from trailer plugs. Thankfully, there are a few simple methods that you can use to get power from your trailer plug. Let’s discuss some of the different ways you can do this, so you can power up your trailer with ease.

Method 1: Use a 12V Battery

One of the most popular methods for getting 12V power from your trailer plug is to use a 12V battery. All you have to do is connect the positive and negative terminals from the battery to the appropriate pins on your trailer plug. This will allow you to power any 12V devices that you have in your trailer. This method is easy to set up, and you can use it to power your trailer even if you don’t have access to external power.

Use a 12V Battery

Method 2: Use a Solar Panel

If you want to power your trailer using renewable energy, then you might consider using a solar panel. A solar panel can be used to convert sunlight into electricity. To use this method, you will need to connect your solar panel to your trailer plug using a charge controller. The charge controller will ensure that your battery is charged correctly, and that you get the most out of your solar panel. This method is great if you plan on spending a lot of time off-grid.

Method 3: Use a Generator

If you have a generator, you can use it to power your trailer via your trailer plug. To use this method, all you have to do is connect your generator to your trailer plug, and then plug your devices into your trailer. This method is excellent if you need a lot of power and have access to a generator. However, generators can be noisy, so keep that in mind when using this method.

Method 4: Use an Adapter

If none of the above methods work for you, you can always use an adapter to get power from your trailer plug. An adapter can convert your trailer plug’s power into a different type of power that your devices can use. You can use an adapter to convert your 12V power into USB power, or AC power. This method is the most versatile, but it might require some research to find the right adapter for your needs.

Dangers Of Getting 12V Power From Trailer Plug

As someone who owns a trailer, you know the importance of connecting it to your tow vehicle securely. You may have tried to extract 12V power from the trailer plug for different purposes, but have you considered the risks involved? When you get 12V power from a trailer plug, you open up a can of worms and put yourself and other road users in danger. Let’s look at why this is a horrible idea and why you should stop doing it.

Voltage Spikes

The constant running of the trailer’s battery will cause voltage spikes as the voltage rises and falls over and over. Your device or gadget that you have connected may not be able to handle this and may be corrupted or damaged by the voltage spikes from the trailer’s battery. So if you need continuous 12V power, get a separate battery rather than taking it from the trailer.

Battery Drainage

Every time you draw power from the trailer’s battery, it runs down the charge, and if you keep doing this, you may find yourself with a dead battery. In case you have plans for using your trailer, the drained battery can prove disastrous, especially if you’re out in the middle of nowhere and cannot get help. Repeated draining of the trailer battery may also cause the battery’s shelf life to decrease or fail to hold a charge when you need the power.


A trailer battery is only meant to supply power to the trailer’s systems such as lighting, water pumps, and other features designed to run on the battery. If you keep drawing power from the trailer’s battery, you may overload it and cause damage to the battery or create a risk of fire and mayhem.

Risk of Electrical Problems

Taking 12V power from the trailer can also cause electrical issues to your tow vehicle or trailer. This can happen if there are electrical mismatches between the trailer batteries and other electrical devices connected to your tow vehicle. Electrical spikes or poor connections may cause electrical fires or damage to the electrical and electronic components of the connected devices.

Safety Concerns

Finally, one of the most significant risks of getting 12V power from the trailer plug is that safety is compromised. More specifically, the brake system on your trailer may fail to work since the battery won’t be supplying the power required to power the brakes. This may result in a catastrophic accident and harm to both the driver and passers-by on the road. [2]

Safety Concerns

When to Ask Professional Help

In this digital era, we rely heavily on gadgets that require a constant power supply. And sometimes, it becomes impossible to recharge them when you are on the go. That’s when getting 12V power from the trailer plug comes in handy. While it’s easy to do-it-yourself, it requires the proper knowledge and tools.

First and foremost, if you’re not confident or comfortable working with electrical circuits, it’s best to seek professional help. Dealing with electrical circuits is dangerous and if not handled properly, it can have severe consequences. A professional electrician ensures that the circuit is correctly installed, preventing any potential hazards.

Secondly, if you’ve tried to troubleshoot and fix the circuit and still can’t get it done, it’s best to ask a professional. Trying to force it without any knowledge of electrical circuits could lead to damaging your trailer plug permanently. Therefore, it’s advisable to seek professional help to prevent any forced damages.

Thirdly, if you’ve just bought a new trailer and aren’t quite conversant with the 12-volt power source, it’s best to ask for professional assistance. Different trailer brands come with different models of 12-volt sockets. Therefore, getting professional help ensures the proper fitting of the sockets, preventing any malfunction or shorts.

Fourthly, if you’ve extensively used the trailer plug over a long period, it’s best to seek professional help for a maintenance check. Like any other gadget, the trailer plug may undergo wear and tear, leading to a malfunctioning circuit. A professional check ensures that the circuit is in good working condition, preventing any possible breakdowns.

Lastly, if you’re unsure about the installation of additional appliances to the circuit, it’s best to ask for professional help. Installing an additional gadget without the proper knowledge can cause more damage than good to the circuit. It’s advisable to seek professional guidance on how to install new appliances to your circuit to ensure that everything fits correctly.


Are trailer plugs 12V?

No, not all wires in a trailer plug are 12V. Trailer plugs have a variety of wires, and each wire is responsible for a specific function. The most common trailer plug is the 7-way plug, which is shaped like a hexagon. The wires in the 7-way plug include a white ground wire, a blue brake wire, a green tail light wire, a yellow reverse light wire, a brown running light wire, a black auxiliary wire, and a red or black 12V power wire.

Does a 12 pin trailer plug charge the battery?

Yes, a 12 pin trailer plug can charge your battery. However, not all the 12 pins are necessarily used for this function. A 12 pin trailer plug follows the same principle as a 7-way plug. The additional five pins in the 12 pin plug provide extra functionality, such as reverse lights, auxiliary power, brake lights, and power for an electric brake controller. However, the 12V power wire in the 12 pin plug can charge your battery.

What wire color is for 12V?

Most trailer plugs use a red or black wire to signify 12V power. This wire is usually used to power a battery charger or for charging your trailer’s battery. However, in some instances, the 12V wire can be brown or green. Always check the manufacturer’s instructions for the correct wire colors.

Useful Video: Ford truck – Lack of 12V Power at 7-Way – why???


Accessing 12V power from your trailer plug is a simple process that can provide a great deal of convenience while on the road. By following these steps and taking care to consider your power needs, you can ensure that your devices stay charged and ready to go while you’re out exploring. Just be sure to double-check your tow vehicle’s wiring and test everything out before heading out on your next adventure. Happy trails!

  1. https://www.rvsupercentre.co.nz/page/using-12-volt-power-in-your-motorhome/#:~:text=12%20volt%20power%20is%20supplied,awning%20and%20toilet%20flush%20system.
  2. https://outbacktravelaustralia.com.au/4wd-mods-diy-workshop/how-to-fit-a-12v-trailer-plug/