For many, installing the electrics is often the most challenging part of a van conversion. With so many different components, wires, and calculations, it’s easy to feel overwhelmed when planning your camper’s electrical system!
In this electrical guide, we break down everything you need to know in order to DIY your own electric system in a camper van. From start to finish. Step-by-step. No prior experience is needed and no electrical engineering degree required. (We’re social science and art majors, and we did fine!)
By the end of this post, you will be able to build your own van electrical system and understand how all the different components and wires come together to power all the devices in your camper. Our goal is to make this guide easy to understand with information that is practical and actionable.
We’re ready for the challenge. And we hope you are, too. So let’s go!
The 5 Parts To A Complete Van Electrical System
A van’s electrical system can be broken down into five distinct sections. In each section, we provide the information and recommendations you need to help answer all the questions you’ll have. Below is a summary of the 5 parts to a functioning camper electrical system.
What kind of batteries and how many of them will you need? Should you wire multiple batteries together in series or in parallel? In this section, you will learn everything you need about the most important part of any electrical system: the batteries!
Most of the electrical devices that you will install in your camper van will likely run on 12V DC. What does this mean? And why? In this section, we show you how to wire 12V devices to your batteries so that they function properly. Don’t fret, intuitive diagrams are included!
Using solar panels is the most popular way that camper vans charge their battery bank. In this section, we teach you how to properly size your solar panel system and wire all your solar components together so that you have a robust off-grid charging solution!
In order to charge most laptops and other regular household appliances, you will need a source of 120V AC power. In this section, we show you how to wire an inverter so that you can run these types of devices from your 12V batteries.
We recommend having at least two ways to charge your batteries. The first is using solar and the second is to connect to your van’s alternator so that you can charge while driving. In this section, we show you how to do just that!
The batteries are the “heart” of any camper van’s electrical system and should be the first components to plan for in an electrics build. Batteries supply the power to run all your devices, such as the lights, USB ports, fan, fridge, laptops, blender, and more.
Before installing any batteries in your camper van, you’ll need to answer three important questions.
- What type of battery do you want?
- How many batteries do you need?
- Will you connect your batteries in series or parallel?
We help you answer each of these questions below.
1.1 - Types of Batteries for Camper Vans
There are four different battery chemistry types that can be used in a camper van. They are:
- Flooded Lead-Acid (FLA)
- Gel Cell
- Absorbent Glass Mat (AGM)
- Lithium-Ion (LiFePO4)
However, only the last two types (AGM & Lithium) offer realistic solutions for camper vans. This is because FLA batteries require regular maintenance and Gel Cell batteries require slower charge and discharge rates, which may not be compatible with van life. And ultimately, both of these two battery technologies have shorter lifespans when heavily used on a daily basis. (Source)
So then which battery chemistry should you choose? AGM or lithium?
AGM vs. Lithium Batteries
In the table below, you can see how the two battery chemistries differ in characteristics.
~2X more energy
~5X longer lifespan
Better in cold
From this table, you can see that these two batteries have different pros and cons. AGM batteries are almost always cheaper than an equivalent lithium battery, but tend to have shorter lifespans and usable energy.
Therefore, to answer the question about which battery chemistry you should use depends on your budget, travel timeline, and van life goals.
To learn more about which battery better suit your needs, read our AGM vs. Lithium battery post.
Our opinion: Lithium (LiFePO4) batteries are the clear winner over AGM. This is especially true as lithium prices have declined substantially in recent years. Check out our post ‘Why Lithium Is Worth It’ to learn more.
Recommended Lithium & AGM Batteries
Based on our experience and the experiences of others, below are our battery recommendations.
Budget Lithium Batteries
Due to their extremely low cost/charge cycle, we believe that selecting a budget, no-frills LiFePO4 lithium battery is the best option for the majority of camper vans. This is especially true if you plan to live in a van for longer than 1.5 years.
Two popular budget models that we recommend:
Premium Lithium Batteries
If getting the best quality power supply is critical for your van life, we 100% recommend using Battleborn batteries. We’ve been using Battleborn for 4 years in our camper and never once had any issue with them. High quality components and customer service.
Two popular premium models that we recommend:
We don’t discount AGM batteries entirely. And for many van lifers, AGMs continue to be the battery of choice to supply their power needs.
If, after reading this article, you believe AGMs still provide the best battery solution for your needs, we recommend the following two AGM models:
1.2 - Connecting Multiple Batteries Together
You can connect multiple batteries together in different ways to increase total battery capacity and overall voltage. Batteries can be connected in either parallel or series. We discuss each type of connection below.
To connect multiple batteries in parallel, connect all the positive terminals together and all the negative terminals together. The effect is that the total amount of current (Ah) increases but the overall voltage (V) stays the same.
To connect multiple batteries in series, connect the negative terminal of the first battery to the positive terminal of the second battery. Then the negative terminal of the second battery to the positive terminal of the third battery. And so on. The effect is that the voltage of the battery bank increases, but the overall amount of current does not increase.
Why increase the voltage? You should only wire batteries in series if you want to increase the voltage of your battery bank. Some campers like to run a 24V system but most choose their battery banks to run on 12V. Read our 12V vs. 24V post to learn more.
Our opinion: Usually only large, sophisticated RVs tend to utilize a 24V system, which offers little benefit for small to medium-sized electric systems. We recommend buying 12V batteries and keeping the system at 12V by wiring multiple batteries in parallel to increase power capacity.
Best Wire Size (AWG) For Battery Connections
If you’ve read our camper van wire size post, then you know we like to keep things simple. For all battery to battery connections, we recommend using high quality 2/0 AWG stranded copper wire. This wire thickness will ensure that you can power all your van’s electrical devices without overheating and is safe for 120V inverters that are rated up to 3000W. (We talk more about inverters in Chapter 4)
We also recommend using 2/0 AWG wire when connecting the batteries to several other downstream electrical components (e.g. bus bars, inverters, & 12V panels). So be sure to get a enough length of red and black wire. 10-15 feet is usually sufficient.
Wire Quality: All wires that we recommend are high quality, pure copper, stranded wires. Many cheaper wires found online are copper-clad aluminum (CCA). CCA wires are cheaper to manufacture and can safely conduct less current (Amps) than pure copper wires.
Additional Components & Tools
To connect the 2/0 AWG wires to the batteries, a copper lug (ring connector) must be attached to the wire end. The ring connector then connects to the battery terminal posts.
To attach the ring connector, you’ll need the following components and tools.
- 2/0 Wire Cutters: You’ll need heavy duty cutters to cut through these thick wires.
- Blade: You’ll need this to strip the wire jacket to expose the bare copper strands.
- Copper Lugs: These lugs attach onto the copper wire ends and connect to the battery. Check the terminal post size of your selected battery so that you know the correct diameter lug you need. In most cases, you’ll need either a 3/8″ or 5/16″ lug.
- Lug Crimpers: Do yourself a favor and spend a bit more for a hydraulic crimper, instead of the cheaper hammer crimper. This makes crimping the lug onto the copper wire much easier!
- Heat Shrink: Add heat shrink to improve the connection between the lugs and the copper wire.
- Heat Gun: Activates heat shrink.
Watch the video below to learn how all these components and tools work together to successfully attach a lug onto stranded wire cable.
1.3 - Calculating How Many Batteries You Need
Power capacity is rated in Watt-hours (Wh) and most 12V batteries that you can find online are rated for 1,200Wh.
In order to figure out how much battery power you need, you must calculate how much power (Wh) your camper van will use in a 24-hour period. The more electrical devices your van has, the more power it will use, and the more batteries you will need.
Do The Proper Calculations: We’ve seen too many camper vans trying to power too many devices with too little battery power. As a result, they are always running out of battery power and their batteries die prematurely and need to be replaced. Take the time to properly calculate an appropriate battery bank size.
To calculate how much battery power you need to sustain your camper’s electrical system, follow these steps.
1.4 - How To Charge The Batteries
There are three primary ways to charge batteries in a camper van.
- Solar Power | This method uses solar panels to convert the sun’s energy into usable power. This is a great option for passive charging throughout the day, just as long as it’s sunny outside. Skip to chapter 3 to learn more.
- Shore Power | This involves connecting a 12V inverter/charger to any outside wall socket. This is a great option for a quick charge if you happen to be located near a socket. Skip to chapter 4 to learn more.
- Alternator power (while driving) | This popular method charges the camper batteries while you are driving. This is a great option during the winter, when solar power is less reliable. Skip to chapter 5 to learn more.
We discuss each of these charging solutions in the subsequent chapters below.
1.5 - Chapter One Summary
At this point, you should have a solid understanding of the following three points regarding the batteries of a camper van’s electrical system.
- What type of battery chemistry you will be using,
- How many batteries you will need,
- How to connect multiple batteries together.
In the next chapter, we’ll discuss how to begin connecting critical components to those batteries to build a functioning 12V system.
The 12V DC System
Now that you’ve selected your batteries and wired them together, you’re ready to assemble the camper van’s 12V electrical system. This section includes connecting the batteries all the way to individual 12V devices, like the ceiling lights, vent fan, and USB ports.
If you follow this chapter to the end, you should end up with a wiring system that is similar to the diagram below.
There’s a lot going on in the above diagram. Lots of different components and wiring. So to help you better make sense of this wiring diagram, we separate this 12V DC system into three parts.
2.1 - Batteries To Bus Bars
The first step when setting up your 12V system is to connect the batteries to the bus bars. To complete the connection between the batteries to the bus bars, we will be wiring four additional components in-between. We talk about each of these components below.
2/0 AWG Wire
2/0 AWG wire is the perfect size to connect the batteries to the bus bars.
This is the same cable we recommend when wiring multiple batteries together. We will also be using this same wire to connect several other devices in the later chapters.
Copper Lugs (3/8" - 2/0 AWG)
If you are using 2/0 AWG wire to connect each of our recommended components below, then you will specifically need these 3/8″ lugs.
These copper lugs come supplied with heat shrink to help cover any bare copper strands for a better lug-wire connection.
300A ANL Fuse/Holder
Fuses prevent unforseen spikes in electrical current from overheating and burning your wires. The 2/0 AWG wires we recommend are welding cables and can safely withstand up to 400A of current. (Source)
We suggest a 300A fuse to protect the 2/0 wire and all downstream electrical devices. You almost certainly will never be drawing more than 300A of power in your camper.
Don’t forget to pick up a fuse holder to house the fuse.
Terminal Post Size: 3/8″
Master On/Off Switch
This master switch keeps you safe from electrical hazards when you a building and maintaining your electrical system.
Whenever we need to add & remove components or touch any electric terminals, we turn the switch to ‘OFF’ to stop the flow of electrical current from the batteries.
Terminal Post Size: 3/8″
Unlike a phone or laptop, 12V batteries do not display their state of charge (SOC) percentage. But by installing a battery monitor, this device will display your battery’s SOC by monitoring the watts as they enter and exit the batteries.
Although pricey, we recommend the Victron BMV-712 because its Bluetooth capabilities allow you to pair the device to your smartphone. Read our battery monitor wiring post to learn more.
Terminal Post Size: 3/8″
Budget alternative: AiLi Monitor
Bus bars are power distribution and collection centers. By connecting your batteries to these bus bars, you can then connect all future downstream electrical components (e.g. the 12V panel, solar charge controller, & inverter) to these bus bars instead of directly to the batteries.
Prioritize proper cable management with bus bars.
Terminal Post Size: 3/8″
Splurge alternative: Victron Lynx Distributor
2.2 - Bus Bars To 12V Panel
With the bus bars now connected to the batteries, you can connect the 12V fuse panel to the bus bars.
100A Circuit Breaker
To protect the electrical wire and the fuse panel, installing a 100A circuit breaker is recommended.
12V Fuse Panel
This fuse panel connects to all your downstream 12V devices and allows for up to 12 device connections. In our van, we connect this panel to our:
- LED lights
- Vent fan
- 12V fridge
- Water pump
- Diesel heater
- USB sockets
2.3 - 12V Panel To Devices
Once the fuse panel is connected to the bus bars, you’re ready to connect all your 12V devices to the panel. Below is everything you will need to get this done.
Ring connector (M8 - 14AWG)
These specific ring connectors fit the M8 terminal posts on the fuse panel. Each 12V device will need two of these ring connectors; one for the positive post and the second for the negative post.
These connectors also come with heat shrink pre-attached for an improved connection to the copper wire.
14/2 AWG Wire
14AWG wire is the preferred wire size to connect all 12V devices to the fuse panel. These wires can handle 240W of power (20A) at 12V, which is more than enough for each of your devices.
We recommend getting ’14/2′ wires, which means two 14AWG wires (red and black) are encased in an outer jacket. This gives an additional layer of protection against vibrations, sliced wires, and short circuits.
Butt Connectors (14 AWG)
Each 12V device comes attached with a short length of red and black wire. You will need to extend these wires to the fuse panel with butt connectors.
These butt connectors also come with heat shrink pre-attached for improved connections to the copper wire.
The connection of each 12V device to the batteries isn’t complete until a blade fuse is inserted into the slots in the fuse panel to complete the circuit.
Blade fuses come in different amp-ratings (color coded). To calculate the correct fuse size for each 12V device, find the device’s peak current draw and round up to the next fuse size.
2.4 - Popular 12V Devices For Campers
Below is a list of popular 12V devices that are commonly installed in camper vans and RVs.
- LED Lights: These 12V puck lights are popular in the van life community. But light strips and fairy lights are also common.
- Ventilation Fans | Proper ventilation is a must for van life. The Maxxfan and FANtastic Fan are the two most popular models.
- USB Sockets | We like these USB/12V combo sockets. The number of electric devices that plug into these two types of sockets is virtually endless.
- Fridges | Our electric fridge cooler is a top 3 van life essential for us. Read our Dometic fridge review to learn more.
- Water Pumps | Pumps water from your fresh water tank to the faucet. The ShurFlo pump is a popular model among van lifers.
- Fuel Heaters | Whether a heater runs on diesel, gasoline, or propane, it will require a 12V connection to the batteries.
- Composting Toilets | Several professionally made composting toilets, like Nature’s Head, include a small 12V fan to exhaust the bad air.
2.5 - Chapter Two Summary
At this point, you should be able to connect all the 12V devices to your battery bank through the bus bars. For more detailed help and explanation, check out the following articles.
The Solar 'PV' System
Relying on solar panels is the best way to keep your batteries charged on a daily basis. Spending the time to install solar panels is worth it. And if you’re on a tight budget, just know that you can build a complete solar system for less than $450.
But before you start randomly buying solar panels and hoisting them up on your van’s roof, you’ll need to answer the following questions:
- What type of solar panels you want?
- What size solar array do you need?
- What size charge controller?
- Will you connect your panels in series or parallel?
We help you answer each of these questions below.
3.1 - Types Of Solar Panels
When building a solar system for a camper van, there are three types of solar panels to choose from.
These are the most popular solar panels for campers because of their durable construction, which includes a rigid aluminum frame and a top layer of tempered glass for added protection.
These panels are much thinner than their rigid panel counterparts and do away with the thick aluminum frame. As a result, these solar panels are highly flexible and have a lower profile, ideal for stealth camping.
These solar panels fold up and store away inside your camper when not needed. The ultimate panels for complete stealth. And when you need to charge, simply take the panels out and point them towards the sun.
Our Opinion: Get rigid solar panels and forget trying to be stealthy. Rigid panels last longer, are more durable, and better withstand scruffs from low branches, dirt, and dust.
3.2 - How To Calculate Your Solar Array Size
It is important to have the proper amount of watts in your solar array because if you install too little wattage, you won’t be able to properly recharge your batteries each day. This can lead to running out of power during the night.
If you already correctly sized your battery bank system (Section 1.3), then figuring out your ideal solar array size is easy. This is because the size of a solar array should correspond to the battery size.
A Common Misconception: Some van lifers calculate their solar array size based on their daily power usage. However, if you properly sized your battery bank to meet your daily power usage, then you should match your solar array size to your battery bank size.
If you have a 12V battery bank, use the below ratios to determine your solar array wattage size.
- If you are using lithium batteries, use a 1:1 ratio of battery bank Ah to solar array watts.
- If you are using AGM batteries, use a 2:1 ratio of battery bank Ah to solar array watts.
Refer to the sizing table below to locate your ideal solar array sized (based on 12V battery Ah size AND chemistry)
Battery Size (Ah)
Solar Array Size (W)
Solar Array Size
3.3 - Series vs. Parallel Connections
Just as when wiring multiple batteries together, you can choose to connect multiple solar panels together either in series or parallel. You can see the wiring differences between the two styles in the graphic below.
Wiring Panels In Series
To wire multiple solar panels in series, connect the negative line of the first panel to the positive line of the second panel. Then connect the negative line of the second panel to the positive line of the third panel. And so on.
The result is that the voltage (V) of each individual panel is added together, but the overall current (A) only equals the output current of a single panel.
Wiring Panels In Parallel
To wire multiple solar panels in parallel, connect all the positive lines together and all the negative lines together using MC4 branch connectors. If you have two solar panels, use a 2-1 branch connector. If you have three solar panels, use a 3-1 branch connector. And so on.
The result is that the individual current (A) of each individual panel is added together, but the overall voltage (V) equals the output voltage of a single panel.
Series vs. Parallel: Which Is Better For Solar?
It is up to you to decide how you like to connect your solar panels together. Panels wired in parallel are more efficient when partially shaded, but require additional components (branch connectors) and you ‘might’ need to install a solar fuse.
Our Opinion: If you only have two solar panels, connect them in parallel for added efficiency in shade. Two panels in parallel do not need to be fused. If you have three or more panels, consider wiring them in series for a simplified wiring process without fuses.
3.4 - Solar Charge Controllers
After the solar panels, the solar charge controller is the most important device in any solar PV system.
What Size Solar Charge Controller Do You Need?
Charge controllers come in different sizes (amp-ratings). The larger the solar array, the larger the charge controller will need to be. Find your ideal charge controller size using the table below based on the total wattage of your solar array (assuming you’re running a 12V system).
Solar Array Size
Our Opinion: We love our Victron charge controller and connect our smartphones to the device via Bluetooth multiple times per day. Check out our Victron charge controller review to learn more.
3.5 - How To Wire A Solar System
In this section, we go over all the wires and components required to connect the solar panels to the bus bars. In the end, your solar system should look like the diagram below.
With so many types and sizes of solar panels on the market, it can be paralyzing to know which panels to choose.
Whichever you do select, make sure you’re getting the highest efficiency solar panels with ‘9BB’ technology, like these panels from BougeRV.
Learn more: What are 9BB solar panels?
Stranded Copper Wire (Red & Black)
It is important that you use the correct size wire when assembling your solar system. The two most important factors that decide solar wire size are:
- Solar panel connection type (series vs. parallel)
- Total wattage of solar array
10 AWG wire is what most camper vans will need, but check out our solar wire calculator post to help you choose the best wires for your solar system.
MC4 connectors are the standardized connection type for solar systems.
Although solar panels come with two pre-attached MC4 connectors, you will need at least one additional pair to complete your system.
Solar Entry Gland
This entry gland attaches to the roof of your van and protects the solar wires as they enter the vehicle from the outside.
Silicone sealant comes included with this product.
Solar Charge Controllers
Charge controllers regulate the voltage from the solar panels to the batteries and is a critical device for any solar system. Check out our additional charge controller resources to learn more:
The circuit breaker protects the solar wire from overheating and all downstream electrical components from any unforeseen surges in power.
The amp rating of the circuit breaker should match the amp-rating of your solar wire, so be sure to size your solar wires first.
Connect your solar wire to the circuit breaker with appropriately sized ring connectors. If using 10 AWG solar wire, these M6 ring connectors will work.
Ring Connectors (To Bus Bars)
Use ring connectors to connect the solar wire to the bus bars. If you use our recommended bus bars, get the M10 connectors.
You must also size your solar wires before selecting your ring connectors. If, like us, you are using 10 AWG solar wires, these exact M10 ring connectors will be what you need.
3.6 - Mounting Solar Panels On Roof
Before hoisting your solar panels onto the roof, there are two things to consider.
Solar Panel Layout
Will you be laying out your solar panels length-wise or width-wise? And which way is the most space efficient?
To answer these questions, you’ll need to know the individual size of your solar panels and the dimensions of your van’s roof. Then you can play around with different configurations to help you decide the best possible fit.
To learn more, read: Solar Panel Roof Layout Design
Direct Mount vs. Roof Rack
Will you be installing the solar panels directly onto your van’s roof with screws and silicone sealant? Or will you install a roof rack first?
- Direct Mount | By installing the panels directly onto your van’s roof, you will have the lowest profile for your solar panels. This is the stealthier option. The downsides are that you will be creating holes in your van’s roof (leak potential) and removing the panels for maintenance will be a hassle.
- Roof Rack | All roof racks increase public awareness to your camper but they offer a less invasive installation process for your panels. Plus, the slim roof racks at Flatline Van Co. are pretty slick.
Our Opinion: We installed the solar panels directly to our van’s roof. They’ve worked great, look streamlined, and we haven’t had any leaks (yet). But we if could do our build again, we’d spend the money on a low profile roof rack instead.
3.7 - Solar System Summary
After reading this chapter, you should have a solid understanding of the following concepts.
- The ideal solar array size that meets your electrical needs.
- Your perfect solar charge controller size.
- How to wire the solar panels to the batteries.
- How to mount solar panels to your van’s roof.
Still have questions? Check out our other solar resources:
The 120V AC Inverter System
To run many common household appliances and most laptops, you will need a source of 120V AC power. The 12V power supplied by the batteries will not be enough to operate these types of devices.
To get 120V power, you will need to connect an inverter to your 12V batteries. An inverter increases the 12V power from the batteries and outputs 120V AC power.
This section will help you answer the following questions:
- What size and type of inverter do you need?
- What size wires are required?
- How to install an inverter and all related components?
We help you answer each of these questions below.
4.1 - How To Size An Inverter For Your Camper Van
Getting the right size inverter that meets your energy demands is important. If you select too small of an inverter, some of your larger appliances may not function properly. There are two factors to consider when sizing your inverter.
Sum Of Total Load
To know your minimum inverter size, you will need to calculate the max wattage your AC loads will require when run at the same time. If you don’t plan to use two certain appliances at the same time (like a hair dryer and blender), don’t add them together. Lastly, be sure to account for an appliance’s peak power and not their continuous power. Some appliances require additional wattage on startup.
Next, take the wattage sum and add 20% to this figure to ensure you don’t trip the inverter’s safety shut-off feature. Lastly, round up to identify an inverter size that is right for you.
Battery Bank Chemistry & Capacity
You must also be conscious that the inverter size you calculated appropriately matches your battery bank’s capacity and chemistry.
Because lithium and AGM batteries have a different Peukert Exponent, we recommend the following ratios of battery capacity to inverter wattage (for 12V battery banks).
- AGM Batteries: 350W of inverter power for every 100Ah of AGM battery capacity.
- Lithium Batteries: 1000W of inverter power for every 100Ah of lithium battery capacity.
4.2 - Standard Inverters vs. Inverter/Chargers
Standard inverters will only take 12V power and convert it to 120V power. For these inverters, electricity only flows in one direction.
However, there are inverters that double as a battery charger. Not only do they convert 12V battery power to 120V, but they can also convert 120V power back to 12V power when connected to shore power to charge the batteries. When you read about charging batteries by connecting to ‘shore power’, you will need to have an inverter/charger model to do this.
But picking up an inverter/charger model will cost you extra. These models can often cost almost twice as much as a standard inverter. For many camper vans, however, this additional cost is worth it.
Our Opinion: If your budget allows, get an inverter/charger. Charging from shore power is a great backup option when solar power can’t meet your energy demands (i.e. during winter or when parked in shade).
4.3 - Wiring An Inverter In A Camper
In this section, we go over all the wires and components required to integrate an inverter into your camper van’s electrical system. In the end, the finished result should look like the diagram below.
We break down the inverter wiring process into three sections:
- Bus bars to inverter
- Inverter to sockets (AC Out)
- Inverter/Charger to shore power (AC IN)
Bus Bars To Inverter
The first step in the inverter wiring process is to connect the inverter to the batteries. Because we already connected the bus bars to the batteries (in chapter 2), we only need to connect the inverter to the bus bars to complete the circuit.
Inverter (Or Inverter/Charger)
At this point, you should know what size inverter you need to power your 120V system and whether you will be getting an inverter only or an inverter/charger combo.
Every inverter has two large terminals (usually color coded in red and black). You will need to connect these terminals to the bus bars.
Learn more: How To Install An Inverter In A Camper
2/0 AWG Wire
2/0 AWG wire is the perfect size for any inverter rated up to 3000W.
This is the same wire thickness we recommend when connecting multiple batteries together and when assembling the 12V system.
Copper Lugs (3/8" - 2/0AWG)
You will need copper lugs to connect the 2/0 wire to both the inverter and to the bus bars. The 3/8″ lugs we recommend will fit the bus bar terminals any any Victron-branded inverter, but you will want to check the terminal size on the particular inverter you selected to ensure these lugs will fit.
Inverter To Sockets (AC Out)
Every inverter has an ‘AC Out’ section and this is where the 120V power gets distributed to all the AC devices in the camper van. In this section, connect 12/3 AWG wire from the inverter to a circuit breaker (and box) and then connect the wire to all the downstream sockets.
The final result should resemble the diagram below.
12/3 AWG Wire
Assuming you won’t be using AC devices simultaneously with a combined wattage of more than 2,200W (which is A LOT for a camper), this 12/3 wire will meet your electrical needs.
12/3 means that there are three 12 AWG wires packed inside an outer jacket. One wire for positive, one for negative, and one for ground.
This breaker box stores the 15A AC breaker. This particular box has two slots for circuit breakers, although we only use one slot in our camper.
Circuit Breaker (15A)
This 15A circuit breaker fits into the breaker box.
Using this circuit breaker protects your 12/3 AWG wire, which is rated for 20A, from overheating and keeps all your downstream electrical devices safe from surges.
If you want to install a socket into your walls (like at home), you’ll need to pick up a gang box to install behind your walls first. Then the socket gets installed onto this box.
Power Outlet & Wall Plate
There are lots of different wall socket types out there. We recommend going to a hardware store and perusing all the styles. We settled on these particular sockets.
Once you’ve selected your socket-style, you will need to purchase a wall plate to frame the socket. If you picked up our recommended socket, these walls plates will work nicely.
Inverter To Shore Power (AC In)
If you have an inverter/charger combo unit, you will also have an ‘AC In’ slot. This is where power from an external socket (shore power) enters the inverter/charger and charges your camper batteries.
12/3 AWG Wire
You can use the same 12/3 AWG wire that you used for the AC Out wiring. This wire is rated for 20A and can handle over 2,200W when connected to shore power.
This is plenty.
The 12/3 AWG wire connects to the back side of this power inlet. The front side of the power inlet faces outside and is connected to a 15A shore power outlet.
Whichever extension cord you get, make sure your cord contains 12 AWG wires. Many cheaper extension cords usually contain 16 AWG wires, which cannot safely conduct as many amps and have a tendency to get hot when connected to shore power.
This high quality extension cord works great for battery charging from shore power.
4.4 - Connecting Inverter To Ground
4.5 - 120V Inverter System Summary
After reading this chapter, you should have a solid understanding of the following concepts.
- How to calculate your ideal inverter size.
- Whether or not you want an inverter or an inverter/charger.
- How to wire an inverter into your camper’s electrical system.
Still have questions? Check out our other 120V inverter resources:
How To Charge Batteries While Driving (From An Alternator)
Being able to charge camper batteries while driving is the second most important battery charging method, after solar power. After a long drive, it’s nice to arrive at a campsite and start the evening with 100% battery charge.
This is arguably the easiest wiring section of all the chapters that we cover. And by the end of this chapter, you should have a wiring system that resembles the diagram below.
The 12V DC to DC charger senses when you turn on your vehicle’s engine and begins to send power from your vehicle’s battery to your electric system’s battery bank. The higher the amp-rating, the faster the charge rate to your batteries.
We like the Victron DC chargers because they work seamlessly between AGM and lithium batteries. And they are also Bluetooth enabled for easy access from your smartphone. Victon’s DC chargers come in 18A and 30A models.
To wire either side of the DC-DC charger, we recommend using 6AWG wire. With a minimum amp-rating of 55A, 6AWG will keep your system safe when using most standard DC-DC chargers.
Make sure you pick up red AND black wire.
50A Fuse & Holder
Use a 50A fuse to protect the 6AWG wire from overcurrent situations.
Copper Lugs (3/8")
Copper lugs are used to connect 6AWG wire to the batteries and fuses. The diameter of the ring is dependent on the specific products you want to connect to. Below are our lug size recommendations for 6AWG wire.
- Car battery: Check your battery for terminal size
- To/From 50A Fuse: 3/8″ ring connectors (6AWG)
- To Bus Bar: 3/8″ ring connectors (6AWG)
Frequently Asked Questions
"What Tools Do I Need To Build A Camper Electrical System?"
The following tools are instrumental to building an electrics system:
- 2/0 wire cutter – Cuts through thick 2/0 wire.
- 2/0 lug crimper – Crimps copper lugs onto 2/0 wire ends.
- Standard wire cutter/stripper – Cuts and strips 10-22AWG wires
- Ratcheting wire crimper – Used to crimp connectors onto 10-22AWG wires.
- Heat gun – Activates heat shrink material
- Digital multimeter – Measures electricity and helps diagnose electrical problems.
"Do You Recommend All-In-One Power Stations?"
These power stations, like the Goal Zero Yeti, are convenient devices that make building a camper electric system quick and easy. And if you have a small, modest-sized electric system and don’t have the inclination to build an entire system from scratch, an all-in-one power station can be a great option.
But convenience comes at a cost. These power stations are relatively expensive for the amount of stored power that you’d be buying. For almost the same amount of money, you can DIY your own battery bank and have 50-80% more power capacity!
And if you plan a more elaborate electric system with numerous 12V devices, then you really should skip these power stations and build your own system.
"Do You Recommend Electric Water Heaters?"
If you have a large enough battery bank and are willing to invest in a 3000W inverter, electric water heaters can be useful addition. However, water tanks do take up valuable storage space and we never took enough showers to justify keeping our tank.
Unless you plan to build an indoor shower stall, we think skipping an electric tank is the smart option. Instead, opt for a solar shower bag. They’re compact, cheaper, and more convenient to use. You can always boil water to fill the bag if the water isn’t hot enough by the end of the day. We use ours ALL THE TIME.
"Do You Recommend Induction Stove Tops?"
Cooking with electricity (as opposed to using propane) can be a viable option but only if you have sufficient battery capacity.
- If using lithium batteries, we recommend having at least 300Ah of battery capacity (at 12V)
- If using AGM, we recommend having at least 800Ah of battery capacity (at 12V).
If you’re not installing a battery bank of this size, we think going with a standard propane cook top is the way to go. Propane is cheap and easy to refill. It’s the reason why we usually don’t recommend induction stoves.
"How Do You Maintain A Camper Electrical System?"
There are three things we like to do to help keep our camper’s electric system in tip-top shape.
- Ensure bolts and screws remain tight: Once every few months, we use a screwdriver and socket wrench to tighten any screws and bolts that may have become loose, due to vibrations from driving.
- Ensure proper battery state-of-charge (SOC): Did you know AGM and lithium batteries like to be kept at different SOCs? For example, AGMs love to remain at 100% charge while lithium batteries prefer to be kept around 40-80%. Read our battery maintenance post to learn more.
- Prepare for long-term storage: When prepping to store the camper for long periods of time, we shut off our electric system and keep our lithium battery bank at ~50%. For AGMs, we would purchase a battery maintainer (trickle charger) to keep them consistently charged at 100%.
"Can You Make Me A Custom Wiring Diagram?"
We’ve recently started receiving several of these custom wiring questions every month and, unfortunately, we need to start declining these requests. We put a lot of love into our wiring diagrams, but they do take up a lot of our time.
If you are looking for diagrams that are a bit more customized, check out our “Custom Solar Wiring Diagrams” in our eBooks download page. We detail four different solar builds for four different budgets, from <$450 to ~$6,500.
Electrical System Regrets
Wires Are Not Secured Properly To Van
When we laid our electrical wire throughout the van, we simply taped the wires to our van’s frame and insulation boards. Big mistake.
Next time, we would use a combination of split wire loom and cable zip tie mounts to properly secure all our wires to the van.
Poor Choice Of 14 AWG Wire Type
When purchasing our 14AWG wire, we opted for the most flexible wires possible. This led us to these silicone jacket wires. However, these silicone jackets offer much less protection than these much sturdier 14/2 AWG wires, which have an additional outer jacket for extra protection.
We hope you enjoyed reading our camper van electric system guide and hope you found the information useful. Building your own system takes time and lots of homework, but if you go slow and are careful, we’re confident you can arrive at a successful installation.
If you have any questions, please feel free to send us an email through our contact page.
Lastly, be sure to check out our eBooks with useful wiring diagrams. They are a valuable resource and are all completely free to use.
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