Overland Electrical Systems Basics
Anyone who has camped will be familiar with using various battery-powered devices to make the experience more comfortable and safe. Flashlights, lanterns, walkie talkies, and GPS navigation systems can add convenience, comfort and a margin of safety to backcountry exploration. Overlanders often take this to another level.
Overlanding by definition is a form of vehicle based adventure travel. Because overlanders have a vehicle and possibly a trailer at their disposal, it’s possible for them to bring more capable battery-centered electrical systems into the backcountry.
In this article, we will provide a high-level overview of the electrical systems commonly built into overlanding vehicles and trailers. We’ll touch on the various types of overland electrical systems and provide links to resources with more information on particular types of setups.
What Are Overland Electrical Systems?
Simply put, an overland electrical system is a way to capture, store and use electricity while traveling in the backcountry. Such systems aren’t unique to overlanding and vehicle-based adventure.
Backpackers, cyclists, and boating enthusiasts often have various systems for capturing energy in batteries to store for later use. Overlanding systems are similar to those seen in boats, being larger capacity and often connected to a motor or fixed solar system.
For off-roading and overlanding, electrical systems are typically either found in a vehicle or a trailer connected to a vehicle, in which case the trailer and vehicle can either be isolated electrically or connected together (more common, as the vehicle’s motor can be used to charge a trailer’s batteries.)
Generally speaking, in an overland electrical system a power generator or multiple power generators produce electrical energy that is stored in batteries. These batteries then power electrical devices such as vehicle- or trailer-mounted lights, winches, refrigerators, and water heaters or external devices such smartphones, computers, GPS devices, radios, and fans.
Types of Overland Electrical Systems
As I mentioned before, electrical systems can be found in either a vehicle, a trailer, or some combination of the two. For instance, I have an overlanding trailer that contains a battery charging system that can be charged by my Jeep’s alternator while I’m towing the trailer. People traveling in conversion vans may have a similar set up, but the batteries will be housed somewhere in the van.
In addition to built in systems, it has become more common in recent years to use prebuilt portable power storage systems. Made by companies such as Jackery and Goal Zero, these systems are sometimes called power banks or solar generators (when connected with solar panels).
They have many of the components of an overland electrical system built into them, which significantly simplifies the process of putting together a power system. While these systems tend to be quite a bit more expensive for a given storage and output capacity than built-in power systems, they provide a lot of convenience and portability. I wrote an extensive article already about portable solar generators for overlanding, so I will focus on built-in systems in this article.
One question to ask yourself is whether you even need an extra battery bank. If you have minimal electricity requirements while camping, your vehicle’s primary starter battery may be all you need. If you plan to run larger electronics, such as water heaters and portable fridges, or simply to be off-the grid for a long period of time, a dual battery system may suit your needs.
Below we’ll look at a few examples of overland power setups, but first, let’s survey a few of the common components of such systems.
Components of Overland Electrical Systems
There are different ways to skin the cat when it comes to overland battery systems. Here we’ll describe a fairly standard setup that includes the ability to charge a battery using the vehicle’s motor, solar panels or shore power (electrical power from a campground hookup or home).
This basic overland power system will include the following components: battery, vehicle engine and alternator, solar panel, solar charge controller, wiring harnesses, and fuses.
Types of Batteries
The central component of a backcountry power system is the battery bank. The batteries store energy that can be used to power a variety of devices, from lights to refrigerators. When you are driving, your vehicle’s motor produces plenty of power, but once you stop, it’s up to your batteries to provide energy.
Batteries used for backcountry adventure fall into two broad categories: traditional lead-acid batteries (and their newer incarnations) and lithium ion batteries, a newer technology. In each case, these are “deep-cycle batteries” which produce a steady supply of power to devices and hold a charge for long periods of time. In contrast, the typical car battery is designed to produce sharp spikes in energy, for instance, when turning over the car engine during starting.
Lead Acid Batteries
Lead acid batteries have been around the longest and are the battery typically used to start cars and trucks. While the newer options noted below are rapidly becoming popular for overlanding, lead acid batteries are still used for overlanding and off-roading battery systems as they are a relatively inexpensive and reliable option.
Lead acid batteries are a “wet” battery, where lead electrodes are immersed in an electrolytic solution of sulfuric acid and water. These batteries have long been used as house batteries in overland vehicles and are still the most common – though other battery technologies are rapidly gaining steam.
Lead acid batteries have some downsides. They are relatively heavy and bulky, must be maintained by refilling the electrolyte fluid chamber, and they produce toxic gasses that must be vented. They also charge slowly.
Absorbed Glass Mat (AGM) Batteries
AGM batteries are a type of lead acid battery that incorporates absorbant fiberglass mats that suspend the battery’s electrolyte in a dry state instead of the wet state of traditional lead acid batteries.
This provides a number of advantages over traditional lead acid batteries, including faster charging, higher voltage output, vibration resistance and no outgassing, and no need to refill the battery with fluid. They are a type of valve regulated lead acid (VRLA) battery that has a valve that prevents outgassing.
One thing to keep in mind is that AGM batteries require different charging protocols than traditional lead acid batteries, so if you chose a deep cycle AGM battery for your overland setup, you’ll need to install a compatible charger. While AGM batteries are superior to traditional lead acid batteries in many ways, they are also more expensive.
Lithium Ion Batteries
Another newish technology, lithium ion batteries offer many advantages over traditional lead acid batteries and AGM batteries, including faster charging, lighter weight and a more compact size. They are also the most expensive – but well worth the money, especially for off-roading and overlanding.
Like AGM batteries, lithium ion batteries are a dry battery, where the electrolyte is suspended in a solid matrix. The advantages that lithium ion batteries have over lead acid batteries stems from the lithium ion chemistry. The batteries have a higher energy density than lead acid batteries, which allow for a large amount of energy to be stored in a smaller lighter battery. The batteries also charged more quickly.
There are several types of lithium-ion batteries. The type that is currently most popular for overlanding and conversion van systems are lithium iron phosphate (LiFePO4) batteries. A number of companies make these batteries, including Battle Born, SOK, and Revolution Power Systems.
Batteries store energy, but they don’t create it. That’s where power generation comes in. The most common sources of power overlanders use to charge their battery banks are their vehicle engine, which generates electricity via the alternator, and solar panels. It’s also possible to use small windmills to charge batteries, but it’s rare to see people using this technology.
We won’t go into the details hear, but for each of the power sources below, their may be additional circuit devices such as charge controllers, inverters and fuses that are required to connect them to your battery pack.
Many off-road and overlanding enthusiasts have traditionally installed a dual battery system that includes a vehicle battery, used to power the vehicle’s starter, lights and other electronics, and a “house” battery used to power auxiliary systems such as camping lights, water heater pumps and portable electronic refrigerators. We’ll get into the details of dual battery systems in a separate post.
In such dual battery systems, the vehicle battery and the house battery are charged by the vehicle’s engine when it is running. When in camp, you can then use the stored energy to power your light and other devices. See below for more details about the electrical output of alternators.
One reason people install additional batteries in their vehicle or in a trailer is that electrical devices can drain the starter battery so much that it won’t start their vehicle. In addition to offering extra power, a second battery isolates these devices from the starter battery preventing them from killing your battery.
In recent years, as solar panels have gotten smaller, cheaper and more powerful, they have become a common way to charge battery banks used in RVs, conversion vans and overlanding rigs.
Solar panels come in a variety of forms now as well, from metal encased panels that are permanently mounted on vehicle or camper roofs to thin panels that can be folded down and stowed away when not in use.
While pre-built power banks now almost always have inputs for solar panels built in, you’ll need to set up a charge controller to connect solar panels to a DIY overland power system.
Fuel Powered Generators
For a long time, gasoline powered generators were the only way that people could recharge their battery banks while traveling overland or in RVs. Solar panels have provided a much welcome alternative, as generators are heavy, noisy and polluting. That said, if you are headed into areas where it is essential to generate electricity when not driving and sunshine is limited, a generator might be your only option.
While generators inevitably produce fumes and are noisier than solar panels, newer models of generators are quieter and smaller than those of yesteryear. They also produce quite a bit of energy, so you can use one to recharge your battery bank quickly – which is an argument for installing a fast charging battery bank.
While batteries and power generators form the primary parts of an overland electrical system, there are several other key components. A charge controller, also known as a voltage regulator, is one of these. A charge controller prevents the charging source from overcharging batteries and prevents the batteries from losing energy when the charging source isn’t providing current.
The most common of these are solar charge controllers, which are required for managing the charge that comes into the battery from solar panels. People will also install charge controllers for power coming from the vehicle’s engine. In some cases, charge controllers provide additional information about the system, such as displaying how much charge is left in the battery bank.
If you’re shopping for a solar panel controller, you’ll likely come across two different types: Pulse Width Modulation (PWM) controllers and Maximum Power Point Tracking (MPPT) controllers.
PWM controllers are the more traditional type of controller. They work by regulating the amount of power that flows from the solar panels to the batteries. By doing this, they help to prevent the batteries from being overcharged. PWM controllers are typically less expensive than MPPT controllers, making them a good option for budget-conscious shoppers.
MPPT controllers, on the other hand, are designed to maximize the amount of power that is drawn from solar panels. By using advanced algorithms, they are able to constantly adjust the flow of power in order to ensure that the batteries are being charged as efficiently as possible – around 30 percent more efficient than PWM controllers. MPPT controllers tend to be more expensive than PWM controllers, but they can ultimately help you to get more power out of your solar system.
So, which type of controller is right for you? If cost is your primary concern, then a PWM controller may be a good option. However, if you’re looking to get the most out of your solar system, then an MPPT controller is likely a better choice.
Another key component of a backcountry power system is the inverter, a device that modulates the power produced by the battery so that it can be used for a variety of applications. Inverters typically serve as the outlet that you plug various electronic devices into, whether it’s house lights, a portable fridge, radios, or personal electronic devices such as smartphones and laptops.
The inverter is required to convert direct current coming from the batteries into alternating current for devices that run on AC. For DC powered devices, you can operated on a DC circuit from the battery and don’t need an inverter.
When dealing with electrical systems, fuses are your key safety device. Power can surge through a system for a variety of reasons, which can damage expensive components and cause fires. Fuses prevent these undesired outcomes by breaking a circuit that becomes overloaded.
Some devices such as charge controllers and inverters have fuses built in. You may also need seperate fuses in certain portions of your system.
Switches are the final component we’ll mention here. Switches can be placed in a circuit to control lights, pumps, lifts and other devices. These may be simple on-off toggles or more complex devices such as dimmer switches.
In many cases you won’t need switches, as the end use devices (radio, laptop, water heater, etc.) will have their own controls built in. But for managing built in systems such as hard wired lighting and custom built water heaters, you will likely need to install your own switches.
Example Overland Power Systems
Now that we’ve introduced the basic components of an overland system, it will be helpful to provide you with some concrete examples. Otherwise, it can be a challenge to wrap your head around it – at least that was my experience when I first dove into setting up my own system.
Below we’ll take a high-level look at some common overland electrical systems. We’re not going to cover a pre-built portable solar charger system, as we covered those in a separate article.
Please note that the schematics below don’t necessarily capture the level of detail you’ll need to build a DIY power system – they are meant to provide a general idea of how such systems are assembled with the major components. Also, consult with the component manufacturers and documentation to make sure that you are using batteries, charger controllers, wires, and fuses that are compatible.
Basic Vehicle-Powered Power System
The first system we’ll look at is a dual-battery system that relies on your vehicle’s engine (via the alternator) to charge a house battery used to power auxiliary devices such as lights, fridges and water heaters.
In smaller off-road capable vehicles, the extra battery has traditionally been housed in the engine compartment, next to the starter battery. One thing to note about the schematics below is that all of the battery output doesn’t have to go to the inverter. DC powered devices, such as house lights and water pumps, can be wired directly to the battery (with proper fuses/breakers/switches), since they don’t need the current to be converted to AC.
In a basic dual battery system, the output from the vehicle’s alternator charges both batteries. Because the alternator puts out current that is designed to charge such batteries, a charge control is not necessarily needed.
That said, a battery isolator is installed to prevent the house battery from drawing on the starter battery when devices are drawing power from the inverter attached to the house battery. This is a safety mechanism intended to prevent you from draining your starter battery and becoming stranded in the backcountry. The system is fused and grounded in several locations.
Solar-Only Battery System
Now that we’ve talked about a system that only uses the engine’s alternator to charge the house battery bank, let’s look at a system that uses only solar to charge it.
The primary difference between a traditional dual battery system and a solar powered system is that solar panels generate electric current in a voltage range that can damage the batteries. To avoid this damage, you will install a solar charge controller between the solar panels and the battery.
The charge controller regulates the voltage of the current coming from the solar panels to match the specification of the batteries and it prevents the battery from overcharging, which can damage it. The controller also prevents electric current from leaking back out through the panels at night, when they aren’t generating power.
Hybrid Power System
A common set up for overlanding rigs is to have the house battery bank charged by either solar or by the vehicle’s alternator. In this setup, the current flows from the solar panels and the alternator into the charge controller, which then feeds the current into the battery.
Setting this kind of system up is a bit more complicated, but provides two ways to generate power. This can come in very handy when the weather prevents the solar panels from generating much current or when you are driving a lot and can charge your system on the move.
In this scenario, you’ll need a charge controller that is capable of receiving inputs from the solar panels and the alternator. Some models of charge controller incorporate battery isolation, so you won’t need a separate battery isolator to prevent the starter battery from being depleted by your auxiliary “house” devices.
Key Electricity Concepts
Due to all of the terminology and various components electrical systems can be confusing. Below, we’ll unpack some of the common terms and concepts that are necessary to understand how an overland electrical system works and how to piece one together yourself.
Alternating current vs direct current
While alternators produce alternating current (AC) initially, this current is converted to direct current (DC) by a device in the alternator called a rectifier to run devices in the vehicle. So the output of an alternator is DC. A vehicle’s battery also outputs DC power.
A scientific understanding of the difference between AC and DC isn’t absolutely required, but it is important to remember that some devices will run on one type of current and not the other. If you want to run AC-compatible devices from your battery bank, you’ll need to convert from DC to DC through the use of an inverter. Some models come with outlets integrated into the inverter, but you can also get just the inverter to send power to outlets elsewhere.
Another factor to keep in mind is voltage, a measure of the potential of an electrical force or, put more simply, the electrical force it produces. If you think of electricity as water in a dam, voltage is a measure of the pressure forcing the water out of the bottom of the dam. A high voltage electrical device will produce a higher “pressure” of electricity as it flows out of a wire.
Vehicle alternators generally produce 13.5 to 15 volts while the vehicle battery generates 12 volts. A power outlet in a home or campsite in the United States will typically output 120 volts – though houses also sometimes have 240 volt outlets for running dryers and other devices that draw a lot of energy. Many portable electronic devices run on 12 volts, but it’s important to make sure you are running devices on the correct voltage.
Some larger overlanding and camping devices, such as portable fridges, can run from both 12 volt and 120 volt power sources – and some can operate on a wide range of voltages, which makes them great for travel in other countries..
One advantage of pre-built portable power storage devices is that they modulate the current to provide plug in outlets for various types of devices. If you are building a system yourself, you’ll need to make sure you have the properly modulated outlets for the various devices you’ll want to run.
Amperage is another important electrical concept to keep in mind when building an overland electrical system. Similar to voltage, amperage is a measure of electrical current. While voltage is the force that allows electrons to flow through a circuit (the “dam” of electrical potential mentioned earlier), amperage is a measure of the actual volume of electrons flowing through a point in a circuit. Current is measured in amperes or “amps.”
One way to picture this is to consider a charged battery with a small wire coming out of it. The battery has a certain amount of electrical potential – it’s voltage – that it is capable of generating. A small wire will only allow a small volume of electrons to pass through during a given time, so it has a small amperage. A larger wire would allow a greater flow of electrons and thus be capable of a larger amperage, even though the voltage of the battery remains the same.
Amperage is important in overland electrical systems, as different devices require different amounts of current to operate. Installing the correct wire gauge and other components to handle a certain amperage will ensure your devices have enough power and prevent a failure in your system.
Watts are another unit of measurement that you’ll seed on electronic devices, and is the product of the voltage and the amperage. The formula is as follows:
Watts = Amps X Volts
Wattage is a measure of electrical power, either the amount a device produces or consumes over time. Wattage can be very helpful in matching power sources to devices that will use the power.
For instance, a battery that can produce 1000 watts of power could theoretically power a device that uses 100 watts per day for 10 days without needing a recharge. Of course there are other factors at play, such as ambient temperature, but you get the picture.
Battery powered systems such as those found in overland rigs, RVs and conversion vans require a path for the current flowing through the system to return back to the negative side of the battery.
Circuits in the system, including those that flow through the various components can be grounded directly to the negative terminal on the battery. The battery is also grounded to the vehicle’s frame, so you can ground components that aren’t near the battery to frame instead.