Should I Wire My Campervan Leisure Batteries in Series or Parallel?
That, my friends, is the question. There comes the point in every van conversion where we must tackle these problems. They’re complex and confusing. Today, we’ll discuss the following:
- What do series and parallel mean in camper wiring?
- What is the difference between series and parallel for your campervan electrical system?
- Pros and cons of series and parallel?
- How to connect campervan leisure batteries in series?
- How to connect campervan leisure batteries in parallel?
Camper Wiring: Series and Parallel Meaning
First of all, we have to understand what the terms series and parallel mean.
Firstly, camper wiring in series means that components are connected end-to-end, providing only one path for the current to flow. For example, imagine water flowing through a pipe. In a series circuit, the water flows from the main pipe and through your boiler to the kitchen tap.
A parallel circuit is the opposite. There is more than one path for the current to flow. Connect electrical cables to branches in the circuit to create a parallel circuit. In this scenario, your water pipe splits into 2 – allowing the water to flow freely to the boiler and the kitchen tap.
In the same way, the water flow must split between the two branches, and so must the electrical current in a parallel circuit.
Camper Wiring: Series Vs Parallel
Next, we will examine how current and voltage differ within series and parallel circuits within camper wiring.
Regardless of whether your camper wiring circuit is series or parallel, the same total energy and power will be available from your batteries. It is important to say that how it is connected will determine the voltage and current at various points in the system.
Similarly in water pipes, the current in a series circuit will be the same at all points in the circuit. In parallel, however, the current will be equal to the sum of the current through each branch.
On the other hand, voltage is the opposite. In parallel, the voltage is the same across all branches of the circuit whereas in series, the total voltage is the sum of the voltage across each component.
It may seem like we’re getting into the nitty gritty of camper wiring here, but this is the important part when it comes to deciding how your batteries (and solar panels – but more on that later) will be wired.
Camper Wiring In a Nutshell
- Batteries wired in series – will increase the voltage of the system while the current stays the same as if there were only one battery.
- Batteries wired in parallel – will result in an increased maximum current flow and capacity, but the voltage will be the same as if there were only one battery.
What Does This Mean for My Campervan Electrical System?
Let’s assume for now that you’re using two 100Ah, 12V batteries. If they’re wired in series, your circuit will be 24V, but the maximum current you can draw will be 100Ah. If wired in parallel, your circuit will be 12V, but you’ll be able to draw a higher maximum amp hours – 200Ah.
When buying your appliances inside your van (like your USB chargers, lights, heater, etc.), they’ll be specific to one voltage. This means that lights designed to work on a 12V system will not work if you wire your multiple 12V batteries in series. This is why we can’t use household electrical products in your campervan. They have been designed to be used with 230V.
So the real issue behind how your batteries are wired is what voltage you want your system to be.
What Is Better: Camper Wiring in Series or Parallel?
The act of choosing if you want your campervan leisure batteries wired in series or parallel comes down to the size of your campervan electrical system. Most systems will be fine with a 12v system, therefore wiring in parallel is best. However, some very large systems will want a 24V system which requires the leisure batteries to be wired in series.
12V System: When To Wire a Campervan Leisure Battery in Parallel
For most van owners, you will want a 12V system powering your appliances. Most roof fans, van lights and USB chargers are available for a 12V circuit, which will dictate connecting your batteries in parallel.
As a rule of thumb, any appliances that pull less than 3000W can run off a 12V system without significant difficulties. However, if you plan on running any appliances that draw more than 3000W, you may want to consider a 24V system.
24V System: When To Wire Campervan Leisure Battery in Series
Trying to run an induction hob or similar power-hungry appliance using a 12V system will need you to install cables with a much larger conductor.
Larger cables are used to supporting larger current draws and are more expensive and more awkward to install (since they can’t bend as easily and may not fit through small spaces in your van). This is why larger systems with large power draws may favour wiring your batteries in parallel to increase the voltage. Also, it could let you half the size of your cables!
Camper Wiring In Series Vs Parallel: Advantages and Disadvantages
Wiring in Parallel
Advantages of Parallel:
- Directly power 12V appliances – Many appliances, such as lights, roof fans and USB charges, use 12V. These can be powered directly from your campervan leisure battery without needing an inverter.
- Straightforward charging – 12V batteries are the norm in the industry. Therefore you will have an easier time finding solar panels, battery chargers and battery-to-battery charges that work with 12V systems.
- Redundancy – If you have your batteries in parallel, and one stops working, you can still power your appliances from the other.
Disadvantages of Parallel:
- Thicker cables are more expensive – Having a low voltage system means you will have a high current. This high current requires thick wires, which are more costly than their thinner counterparts.
- Thicker cables can be harder to fit – Thicker cables are less malleable than thinner cables, which can sometimes mean they are harder to install in tight places.
Wiring in Series
Advantages of Series:
- Thinner cables are cheaper – Having a high-voltage system means you will have a lower current. This low current means you can use thinner wires, which are more affordable than their thicker counterparts.
- Thinner cables are easier to fit – Thinner cables are more malleable than thicker cables, which can sometimes mean they are easier to install in tight places.
Disadvantages of Series:
- Need inverter to power 12V appliances – Many appliances, such as lights, roof fans and USB charges, use 12V. If wired in series, you will need an inverter to step the voltage from 24V to 12V to power your 12V appliances.
- Charging Difficulties – 12V batteries are the norm in the industry. Therefore you may have a more difficult time finding solar panels, battery chargers and battery-to-battery charges that work with 24V systems.
- Single Point of Failure – If you have your batteries in series, and one stops working, your whole electrical system will be down as the circuit will be broken.
Camper Wiring: Our Recommendations
In general, camper wiring of 12V batteries in parallel offers the optimal solution for most van converters. 12V appliances are relatively easy to come by, and conductor sizes won’t be too onerous for most applications.
However, a few niche conversions may require wiring in series to achieve 24V or even higher.
- Van lifers who want to go gas-free by installing an induction hob and electric heating.
When converting a double-decker bus or something larger than your average van, your starter battery might already be 24V. Therefore, it would make sense to keep the rest of your system at 24V.
If you think this applies to you, we’d recommend getting in touch with our team before you make any concrete decisions or start placing orders. We fully appreciate that there’s a lot to be considered here. Our expert team can help you dive deeper into this subject.
How to Wire Camper Batteries in Parallel
To wire your batteries in parallel, you will need to connect the positive terminal of one battery to the positive terminal of all other batteries in your array and vice versa for the negative terminals. This is shown for a simple 2- and 3- battery collection in the diagrams below.
This is pretty straightforward to do, but it’s worth ensuring that the connections to the positive and negative busbars are made from the opposite ends of the battery array and that the cables between your battery array and busbars are the same lengths. This will ensure your batteries are loaded equally instead of constantly draining one before the others.
How to Wire Camper Batteries in Series
Camper wiring in series is rarely the way to go, but if you believe this is the approach that’s best for what you are looking to get from your van conversion, then please get in touch with one of our team, and we’ll be happy to help design a system that meets your needs.
Additionally, you will have to consider balancing your total battery capacity and required system voltage with the battery technology and how many batteries will make up your array. Wiring in series is generally done with 12V batteries to produce a 24V or 48V collection (using 2 or 4 batteries, respectively).