So, you’re designing your campervan’s electrical setup, and now you’re faced with a big decision—what voltage should you go with? Should it be 12V, 24V, or even 48V?
It might seem like just another technical choice, but it can impact the overall design and cost of your setup, especially when it comes to things like wire sizes and component choices.
Don’t worry if it all feels a bit overwhelming right now – that’s exactly what this guide is for. By the time we’re done, you’ll have a much better idea of which voltage makes the most sense for your setup and your needs.
This guide will help you get started, and if you’re looking for more in-depth guidance, the Campervan Electrics Handbook is a great resource to have by your side.
What Is System Voltage?
Before we dive into the different options, let’s take a moment to understand what system voltage actually means. Simply put, the system voltage of your campervan refers to the voltage level at which your electrical system operates.
It’s kind of like choosing the size of a water pipe—bigger pipes can carry more water, and smaller pipes carry less. In electrical terms, higher voltages allow more power to flow using thinner wires, while lower voltages might need thicker wires to move the same amount of power.
Your system voltage directly affects things like how much power you can safely use, the type of components you’ll need, and even how your campervan’s batteries and charging systems interact.
For most campervans, the common options are 12V, 24V, and 48V, and each has its pros and cons depending on your power needs and setup.
Choosing the right system voltage means finding the balance that fits your power consumption, wiring layout, and future plans. And don’t worry—it’s not as complicated as it might sound. By the end of this guide, you’ll know which one is right for you.
Overview of System Voltages: 12V, 24V, and 48V
Choosing between 12V, 24V, and 48V depends on what you need from your campervan’s electrical setup. Here’s a closer look at each:
12v Systems
A 12V system is the most popular choice. It’s simple and straightforward, and many appliances like fridges, lights, and water pumps are designed to run on 12V, making it easy to find compatible parts.
If your power needs are moderate—maybe you’re looking to power some basic lighting, a fridge, and charge a few devices—a 12V setup can be a great fit. It keeps things simple and helps keep initial costs down.
However, because 12V is a lower voltage, you’ll need thicker cables to handle larger power needs or longer wire runs, which can add to the cost if you expand your setup later.
24v Systems
Moving up to 24V can be a smart move if you have more power-hungry appliances or longer cable runs.
With 24V, power loss over long distances is reduced, allowing you to use thinner wires compared to a 12V system. This can be particularly useful in larger campervans where appliances might be spread out.
While there aren’t as many appliances specifically designed for 24V, you can use converters to drop down to 12V for things like lights and USB chargers.
This makes 24V a good middle ground if you’re looking for more efficiency without needing the power of a 48V system. It’s a bit more complex than 12V but can pay off with improved efficiency if you need more power.
48v Systems
For those with heavy power needs or plans for off-grid living, a 48V system might be the best option. It’s ideal for setups with large inverters, multiple appliances, or significant power demands like air conditioners.
The higher voltage means you can use much thinner cables, which helps keep weight and costs down when running wires over longer distances.
However, a 48V system is more complex and generally suits those who are comfortable with advanced setups or plan to hire professional help. Compatibility can also be a concern since not all appliances are available in 48V, so it’s important to plan your setup carefully.
The Impact of Circuit Lengths on System Voltage Choice
When it comes to designing your campervan’s electrical system, circuit length plays a big role in deciding which voltage is right for you. The longer the distance between your battery and the devices you’re powering, the more you’ll encounter voltage drop. Essentially, voltage drop happens when electrical energy loses some of its “push” as it travels through a wire, especially over longer distances.
In a 12V system, managing this voltage drop means using thicker wires to ensure that enough power reaches your appliances, even when they’re placed further from the battery. These thicker cables can get bulky and expensive, especially for higher-powered devices or longer runs. But with a 24V or 48V system, the higher voltage means you can use thinner wires while maintaining the same level of power delivery. This can simplify installation and help reduce costs on cable materials.
For example, running a 200W device over a 10 metre distance would require a much thicker wire in a 12V setup compared to a 24V or 48V one. By choosing a higher voltage, you can use a thinner and more affordable cable without compromising on the power your devices receive.
For a deeper dive into how circuit lengths affect your campervan’s electrical setup, check out our article, Why Circuit Lengths Matter in a Campervan Electrical Design. It covers everything you need to know about managing voltage drop and choosing the right wire sizes to keep your system running efficiently.
Alternator Size and Its Influence on System Voltage
Your alternator plays a key role in keeping your campervan’s batteries charged while you’re driving. It’s designed to recharge your starter battery and can also help power your leisure battery bank through a DC-to-DC charger. A DC-to-DC charger is necessary to properly manage the charging process, ensuring that your leisure batteries get the right charge from the alternator without overloading or undercharging them.
Most campervans come with a 12V alternator, so choosing a 12V system for your leisure batteries makes everything simpler. When the leisure batteries are the same voltage as the alternator, the DC-to-DC charger has a straightforward job: it matches the power from the alternator to the leisure batteries without needing to convert the voltage significantly. This keeps the charging process more efficient and reduces the chances of complications or inefficiencies.
However, if you opt for a 24V or 48V system while your alternator is 12V, the DC-to-DC charger has to step up the voltage from 12V to 24V or 48V to charge your batteries. This can be done, but it adds complexity to the system, potentially reduces charging efficiency, and can increase costs since higher-capacity DC-to-DC chargers are more expensive.
Sticking with the same voltage as your alternator simplifies things by minimising conversion needs and potential energy losses. It’s especially useful if you want to keep your setup straightforward and reduce the number of components involved. For many van owners, this makes a 12V system the easiest and most cost-effective choice when their campervan already has a 12V alternator.
But if you have higher power needs that make a 24V or 48V system more appealing, the trade-off is a more complex charging setup. This is worth considering if you’re comfortable with a bit more installation work and managing the additional equipment.
Existing Equipment and Its Impact on System Voltage
When choosing a system voltage for your campervan, it’s important to think about the equipment you already have. If your existing gear—like appliances, batteries, or your alternator—doesn’t match the voltage you’re considering, you’ll need to adapt it using converters or chargers, or rethink your system voltage. Here’s how this plays out:
Imagine you have a heater that runs on 24V, but you’re planning to use a 12V system for your campervan. You’ll need a step-up converter to boost your 12V power up to 24V just for the heater. It’s a way to keep your heater, but it does add extra equipment and complexity. Alternatively, you could go with a 24V system, which would power the heater directly without needing converters.
Now, let’s say your van has a 24V alternator and starter battery, but you want a 12V battery system for your campervan. Here, you’d need a step-down DC-to-DC charger to convert the 24V power down to 12V, allowing your alternator to safely charge your 12V batteries. But if you matched your campervan system to the alternator’s 24V, you could skip the conversion and keep things simpler.
The reverse is also true: if your alternator is 12V but you want a 24V system, you’ll need a step-up DC-to-DC charger to boost the 12V power up to 24V. This lets you use a 24V battery bank with your existing alternator, but it does mean adding extra components.
Even if you decide on a 24V system, you might have a few appliances that still run on 12V. In that case, a step-down converter will drop the 24V down to 12V for those devices. It’s a handy way to keep using your 12V gear without switching everything over.
In short, it’s often easier to stick with the same voltage as your existing equipment, especially your alternator, because it avoids the need for extra converters. But if a different voltage fits your needs better, you can make it work with the right adjustments—just keep in mind the added costs and complexity.
Cost Implications of Different System Voltages
It’s easy to assume that higher voltage systems like 24V or 48V will save you money thanks to smaller wires and bus bars, but it’s not always that straightforward.
With a higher system voltage, you can use thinner cables, smaller fuses, and more compact busbars and switches. But unless you’re working with a very large or power-hungry setup, the savings here aren’t always as big as you might think.
Where costs can start to add up is with the appliances themselves. Since 12V is the standard for most campervans, 12V versions of appliances like lights, fans, and water pumps are generally easier to find and tend to be more affordable.
If you go with a 24V or 48V system, you might find that higher voltage versions of some appliances—like heaters and fridges—are harder to come by and can cost more.
This is simply because the demand for these appliances is lower, so there are fewer options on the market, and they often come with a premium price tag.
Another factor to consider is the need for converters. If you choose a 24V or 48V system but still want to use a few common 12V appliances, you’ll need step-down converters to adapt the voltage.
These converters add to the initial setup cost and add a bit more complexity to your system.
In the end, the cost difference between 12V, 24V, and 48V systems will depend a lot on your specific setup and needs.
If you’re working with a smaller, more standard setup, sticking with 12V is often more cost-effective and simpler. But if your energy needs are higher and you’re willing to invest in the right equipment, a 24V or 48V system could be worth the added expense.
It’s all about balancing the initial costs with the long-term benefits for your campervan adventures.
How System Voltage Affects Wire and Fuse Size for Different Voltage Heaters
When wiring your campervan, the voltage of your system—whether 12V, 24V, or 48V—determines the wire and fuse sizes required for the same type of appliance. Below, we’ve provided wiring diagrams that show how connecting a 240-watt heater to a battery bank differs depending on the system voltage.
Each diagram illustrates a different heater: one designed for 12V, one for 24V, and one for 48V. Although the heaters all draw the same power (240 watts), the wire thickness and fuse rating required vary significantly with each voltage. Lower voltage systems like 12V need thicker wires and larger fuses because they draw more current to deliver the same power. As the system voltage increases to 24V or 48V, the current decreases, allowing for thinner wires and smaller fuses to handle the same load.
These diagrams clearly show how system voltage impacts your wiring setup, helping you understand why higher voltages can be more efficient and cost-effective for larger setups or longer cable runs.
Wire and Fuse Size for 12v System Voltage
This diagram shows how a 12V battery bank is used to power a 240W heater through a 10-metre wire. Because the system operates at 12V, a larger wire (6 AWG, 16mm²) and a 20 amp fuse are required to handle the current safely. The thicker wire ensures minimal voltage drop over the 10 metre distance, while the larger fuse provides adequate protection for the circuit.
Wire and Fuse Size for 24v System Voltage
In this setup, a 24V battery bank powers a similarly powered 240W heater over a 10 metre wire. Since the system operates at a higher voltage, the wire size can be reduced to 12 AWG (4mm²) and the fuse size to 10 amps. This illustrates how increasing the system voltage reduces the current needed, allowing for smaller, more cost-effective wiring and fuse sizes.
Wire and Fuse Size for 48v System Voltage
This diagram shows a 48V battery bank powering a 240W heater, again using a 10 metre wire. With the highest voltage system, the wire size can be reduced even further to 16 AWG (1.5mm²), and only a 5 amp fuse is required. This demonstrates the efficiency of higher voltage systems in reducing both wire thickness and fuse size, making installations simpler and more cost-effective.
Impact of System Voltage on Cost of Wiring
Select the system voltage from the dropdown below to see the correct wire size for a 25a circuit and indicative cost for each cable length. This helps illustrate how higher system voltage result in lower wiring costs.
Indicative costs roughly correct as at October 2024.
Factors to Consider When Choosing Your Voltage
Choosing the right voltage for your campervan isn’t just about picking a number; it’s about finding what suits your setup and your travel style. Here’s a quick summary of the main factors to think about when making your decision:
Your Power Consumption Needs
Start by considering how much power you use each day. The more power-hungry your appliances are, the more you might benefit from a higher voltage system like 24V or 48V. A higher voltage can handle bigger power loads more efficiently, making it a great choice for those running large inverters or planning on full-time van life.
Circuit Lengths and Layout
If you’re planning to place appliances further from your battery bank, like running a fridge at the back of a larger van, the length of your wiring matters. Higher voltage systems like 24V or 48V can help reduce power loss over those long cable runs, allowing you to use thinner and more affordable wires.
Alternator Compatibility
Most campervans come with a 12V alternator, so matching your battery system to that can keep things simple. If you want a 24V or 48V system, you’ll need to add a DC-to-DC charger to step up or step down the voltage, adding a bit more complexity and cost to your setup. Matching the voltage between your alternator and batteries is often the easiest way to keep your charging setup efficient.
Existing Equipment
Think about what you already have. If you’re already using 12V appliances, it might make sense to stick with a 12V system to avoid the need for converters. But if you have some key appliances that are 24V or if your alternator is 24V, it might be worth considering a 24V system to simplify your setup.
Component Availability
12V components are widely available and often less expensive due to their popularity. Moving to 24V or 48V can mean fewer options and higher prices for appliances like fridges, heaters, and lights. Make sure you can find the parts you need before committing to a higher voltage system.
Budget Constraints
Higher voltage systems can save you money on wiring and certain components, but they might require more investment upfront, especially for converters or compatible appliances. Weigh the initial costs against any long-term savings or efficiency gains you might see.
Future Plans
Think ahead—do you see yourself adding more appliances or increasing your energy needs down the road? A 24V or 48V system might give you more room to expand without needing a complete overhaul later. But if your setup will stay simple, a 12V system could be all you need.
By weighing these factors, you’ll have a clearer idea of which system voltage makes the most sense for your campervan setup. Whether you stick with 12V for simplicity or go for 24V or 48V for efficiency, the right choice will keep your travels powered up without unnecessary headaches.
How Our Campervan Electrical Design Service Can Help
If you need help making sense of it all, we’re here to lend a hand. Our design service takes your unique needs and crafts a system just for you—saving you time and ensuring everything works seamlessly. Reach out to chat with us about your options!
FAQs
Yes, you can mix 12V and 24V appliances, but you’ll need step-up or step-down converters to match the voltage of each device with your system. For example, if you have a 24V system but want to use a 12V fridge, a step-down converter can safely adapt the voltage. Keep in mind that adding converters can increase the complexity of your setup and might reduce efficiency slightly.
It depends on your needs. A 24V system can be more efficient for larger setups because it reduces the need for thicker cables, which saves space and costs on wiring. However, if your power needs are moderate, a 12V system is often more straightforward and more cost-effective since it aligns with most standard campervan appliances.
Generally, yes. Appliances designed for 24V or 48V systems can be harder to find and often come with a higher price tag due to lower demand. While 12V appliances are more common and tend to be less expensive, choosing a higher voltage system could mean spending more on specific items like fridges, heaters, and inverters. It’s a good idea to check the availability and cost of key appliances before deciding on a higher voltage.
To calculate your daily power needs, make a list of all the appliances you plan to use, including lights, fridges, chargers, and other devices. Find out the power consumption in watts for each item (usually listed on the label), then multiply that by the number of hours you expect to use it each day. Add up the total watt-hours (Wh) for all your appliances to get a rough estimate of your daily power consumption. This will help you choose a system voltage that can handle your needs.
Using wires that are too thin for your power needs can cause voltage drop, overheating, and even pose a fire risk. This is especially a concern with 12V systems over longer cable runs, as they require thicker wires to maintain power. To ensure safety and efficiency, always use a wire size that matches your system voltage and power requirements. You can use our DC wire size calculator to find the right size.
Upgrading from a 12V to a higher voltage system is possible, but it’s not always easy. It may involve replacing your battery bank, installing new DC-to-DC chargers, and potentially adapting some of your existing appliances. If you think you might want more power down the road, it’s worth considering a 24V system from the start, as it offers a good balance of efficiency and compatibility.
24V systems are generally considered safe for most campervan applications, especially compared to mains power. While 24V carries more “push” than 12V, it is still classified as low voltage and does not pose a significant shock risk under normal conditions. However, like any electrical system, it’s important to handle wiring and components correctly to avoid short circuits, overheating, or fires. Proper fusing, good-quality connections, and following safety guidelines will ensure your 24V system operates safely.
To create a 24V system from a 12V power source, you can use a DC-to-DC step-up converter, which increases the voltage from 12V to 24V. This is useful if you have a 12V alternator or battery system but want to power certain 24V appliances or charge a 24V battery bank. Another method is to wire two 12V batteries in series. By connecting the positive terminal of one 12V battery to the negative terminal of another, you can effectively create a 24V battery bank. Keep in mind, though, that wiring batteries in series means the two batteries need to be identical in type, capacity, and age to ensure balanced charging and safe operation.
Conclusion
Choosing the right voltage is a key step in building a reliable and efficient campervan setup. By understanding the differences between 12V, 24V, and 48V systems, you’re already on your way to creating the perfect electrical setup for your adventures.
If you’re ready to design your campervan electrical system or just need some guidance, don’t hesitate to reach out. And if you prefer a DIY approach, the Campervan Electrics Handbook is filled with the kind of insights and examples that can help you get it right.
Happy travels, and remember, we’re here to help if you need it!
