Cable Connections

Correct Cable Termination

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When it comes to terminating cables, there are several methods available, each with its own benefits and considerations. When installing the electrical system within your campervan, selecting the appropriate termination method for each cable is crucial for ensuring a secure and reliable connection.

In this article, we will explore four popular cable termination techniques which you are likely to use in your campervan: lugs, ferrules, ring crimps, soldered, MC4 connectors and direct connections with copper.

Several factors need to be considered in the selection process.

Firstly, the type and size of the cable must be taken into account, as different termination methods are designed for specific cable types and diameters.

Secondly, the application and environment in which the cable will be used play a significant role. For instance, if the cable will be exposed to harsh conditions such as high temperatures, moisture, or chemicals, a termination method with appropriate protective features must be chosen.

Additionally, the electrical load and voltage requirements must be considered to ensure the termination method can handle the expected current and voltage levels without compromising safety.

Lugs

Lugs are widely used in electrical installations to terminate cables. They are metal connectors typically made of copper or aluminium. Lugs are available in various shapes and sizes to accommodate different cable sizes and types. The cable conductor is inserted into the lug and secured using set screws or compression. The lug is then attached to a terminal block.

Benefits of lugs:

  • They provide a mechanically robust and electrically reliable connection.
  • Lugs can handle high current applications and are suitable for heavy-duty applications.
  • They allow for easy removal and replacement of cables when needed.
  • Lugs provide excellent conductivity and can withstand temperature variations.

Considerations:

  • Proper installation techniques and torque specifications are critical for ensuring a secure connection.
  • Correct sizing and compatibility between the lug and cable are important to prevent issues such as loose connections or overheating.
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Method for Crimping A Lug

Select correct size lug & cable
Align lug with cable
Strip insulation to match lug barrel
Insert copper into lug
Ensure crimper is set for the correct size lug
Set crimper around the lug and compress
Crimp as many more times as required
Finish with heat shrink

Ferrules

Ferrules, also commonly known as ‘boot lace ferrules’, are cylindrical metal sleeves used to terminate individual wire strands within a cable. They are commonly made of copper, aluminum, or brass. Ferrules are crimped onto the wire strands using a specialised crimping tool, creating a secure connection. The terminated wire can then be inserted into a terminal block or other connection point.

Benefits of ferrules:

  • They provide strain relief, preventing wire strands from fraying or breaking.
  • Ferrules enhance the electrical contact area between the cable and the terminal, ensuring better conductivity.
  • They facilitate quick and efficient termination, especially when dealing with multiple wire strands.
  • Ferrules offer a neat and organised appearance to cable terminations.

Considerations:

  • Choosing the correct size and type of ferrule for the cable size and application is crucial for a proper connection.
  • Proper crimping techniques and tool selection are essential to ensure a reliable and secure termination.
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Method For Crimping A Ferrule

Select correct size ferrule & cable
Strip cable to the length of the ferrule barrel
Locate cable inside ferrule barrel
Select the correct size crimp and compress the ferrule
Ensure the jaws are fully closed and tight around the barrel
Give the ferrule and tug to ensure its tight around the copper

Ring Crimps

Ring crimps, also known as ring terminals or ring connectors, are commonly used in electrical and automotive applications. They are metal terminals with a circular shape and a hole in the centre. The cable conductor is inserted through the hole, and the ring crimp is then secured using a crimping tool. The ring terminal can be attached to a stud or screw terminal for connection.

Benefits of ring crimps:

  • They provide a secure and permanent connection to studs or screw terminals.
  • Ring crimps are suitable for applications that require frequent disconnections and reconnections.
  • They ensure a reliable electrical connection and help prevent loosening over time.
  • Ring crimps are available in various sizes to accommodate different cable sizes.

Considerations:

  • Proper sizing and compatibility between the ring crimp and the terminal are crucial to ensure a snug fit.
  • Careful crimping is necessary to prevent loose connections or damage to the wire strands.
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Method for crimping a ring crimp

Select correct size ring crimp & cable
Strip cable to the length of the crimp barrel (allow 1-2mm more)
Locate cable inside crimp barrel
Select the correct size crimper and compress the crimp
Ensure the jaws are fully closed and tight around the barrel
Give the crimp and tug to ensure its tight around the copper

Direct Connection with Copper

In some cases, direct connection with copper can be employed. This method involves stripping the cable insulation and directly twisting or soldering the bare copper wire to the desired connection point.

Although this is a termination method commonly used across the electrical industry, we would highly suggest, where you can, always using ferrules when terminating stranded copper cables. Not only does it make the termination neater, its easier to locate the cable into the screw terminals and safer knowing that all strands of copper are contained within a ferrule.

Benefits of direct connection with copper:

  • It is a simple and cost-effective method.
  • Direct copper connections can be easily made and undone without additional hardware.
  • This method is suitable for low-current applications or short-term setups.

Considerations:

  • Direct connections with copper may not provide the same level of reliability and longevity as other termination methods.
  • The exposed copper wire is susceptible to corrosion, oxidation, and physical damage.
  • This method is not recommended for high-current or critical applications.
  • You must ensure there is enough copper to create a sound, secure connection. Hence why in our photos below, the copper is ‘doubled over’.
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Soldered Electrical Connection

A soldered electric connection is a method of joining two or more electrical components together using solder. Solder is a metal alloy with a low melting point that is specifically designed for creating a strong and reliable electrical connection.

The process of soldering involves heating the solder and applying it to the joint between the components. The heat melts the solder, allowing it to flow and form a bond with the surfaces it contacts. As the solder cools and solidifies, it creates a secure and conductive connection between the components.

Soldering offers several advantages for electric connections. It provides a strong mechanical bond, ensuring the components remain securely joined even under vibration or movement, key in any campervan build. . Additionally, soldering creates a low-resistance electrical pathway, allowing for efficient flow of electric current. The solder also helps protect the joint from oxidation and corrosion, which can degrade the connection over time.

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Multi-Contact 4 Connectors

MC4 connectors, short for ‘Multi-Contact 4’, are electrical connectors developed specifically for photovoltaic (PV) systems. They are designed to facilitate quick and reliable connections between solar panels, as well as between panels and other system components such as, charge controllers, and combination boxes.

The main reason for using MC4 connectors in solar panel installations is their superior safety and performance characteristics. Here are some key aspects that make MC4 connectors the preferred choice:

  1. Waterproof and Weatherproof: Solar panels are typically exposed to various weather conditions, including rain, snow, and extreme temperatures. MC4 connectors are designed to be fully waterproof and weatherproof, providing reliable electrical connections even in harsh outdoor environments. This ensures the longevity and durability of the entire solar system.
  2. High Efficiency: MC4 connectors offer low power loss and high conductivity, which are critical for optimising the performance of solar panel systems. They minimise resistance and maximise the power transfer from the solar panels to the rest of the system, resulting in enhanced overall efficiency.
  3. Easy and Secure Connections: The design of MC4 connectors allows for quick and simple connections, reducing installation time and effort. They feature a snap-lock mechanism that securely locks the connectors together, preventing accidental disconnections. This ease of use makes MC4 connectors ideal for both professional installers and DIY enthusiasts.
  4. Compatibility and Standardisation: MC4 connectors have become the industry standard for solar panel connections due to their compatibility with a wide range of PV components. This standardisation ensures that different brands and models of solar panels and system components can be easily interconnected, promoting flexibility and interchangeability.
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Regulations & Standard Compliance

Termination methods and techniques are defined by industry standards and regulations. Following these standards ensures that the electrical system meets the required safety and performance criteria.

Proper termination techniques take into account factors like cable type, voltage rating, current-carrying capacity, and environmental conditions, ensuring that the system is correctly installed, maintained, and inspected.

The choice of termination method depends on factors such as the application, cable type, current requirements, and desired durability. By understanding these different techniques, you can ensure proper cable terminations that meet your specific needs while maintaining safety and performance.

The regulations in BS7671 regarding the termination of cables specify requirements for ensuring safe and reliable electrical connections. Here are some key points from BS7671 in relation to termination:

Cable Selection: The standard provides guidance on selecting the appropriate cable size, type, and insulation based on the specific application, current-carrying capacity, and environmental conditions.

Connection Methods: BS7671 outlines various approved methods for terminating cables, such as crimping, soldering, compression fittings, terminal blocks, connectors, and suitable cable glands.

Correct Sizing: The regulations specify that cable terminations should be correctly sized to match the cable being terminated. This ensures proper contact and prevents overheating due to inadequate contact area.

Mechanical Strength: Cable terminations should have sufficient mechanical strength to withstand mechanical stress, vibration, and pulling forces. This includes the use of suitable supports, clamps, and fixings.

Electrical Continuity: Termination methods should ensure good electrical continuity between conductors, minimising resistance and voltage drop. Proper connection techniques and materials are crucial to achieve this.

Insulation and Protection: Cable terminations should provide adequate electrical insulation and protection against moisture, dust, and other environmental factors. Insulating materials, insulating sleeves, and appropriate enclosures should be used as required.

Accessible and Maintainable: Termination points should be easily accessible for inspection, testing, and maintenance purposes. Adequate clearances and labelling should be provided to facilitate identification and future work.

Compliance with Manufacturer Instructions: Cable termination should be carried out in accordance with the manufacturer’s instructions and recommendations. This ensures proper use of specific termination products and techniques.

It’s important to note that BS7671 is regularly updated, and it is crucial to consult the latest version of the regulations and any applicable amendments to ensure compliance with the current standards.
While the above information provides a general overview, it is always recommended to refer to the specific requirements and guidelines outlined in BS7671, if you do not have the latest edition, we will be happy to help guide you through the regulations. We pride ourselves in working to the regulations and also ensuring our clients are too.

For further information, we’re here to help!

Contact us

Conclusion

Terminating cables correctly is essential for achieving secure and reliable connections in your campervan. Lugs, ferrules, ring crimps, copper connections and soldering are all viable methods, each with its own benefits and considerations. The choice of termination method depends on factors such as the application, cable type, current requirements, and desired durability. By understanding these different techniques, you can ensure proper cable terminations that meet your specific needs while maintaining safety and performance.

Tom Alderdice

Hey, I’m Tom – founder of Tiny Build Electrics

My mission is to help sustainable-minded folks develop their electrical knowledge, giving them the confidence to do their own tiny build electrics.

Book A Consultation  
Victron Tools

Understanding Series and Parallel Wiring: Everything You Need to Know

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One common question that we get asked here at Tiny Build Electrics is in relation to series and parallel. Batteries in parallel? Solar array in series? Pros, cons?

This is a key stage in your Tiny Build and something you definitely want to get right! In this article we are going to break it down into small, manageable chunks to make it easy to understand.

Batteries in parallel

“In parallel the battery voltage remains constant and the amp hours increase”

Put simply, you connect the positive to positive, negative to negative. Easy, right? Well.. kind of!

The diagram below is why this type of connection is called ‘parallel’. The positives and negatives remain parallel to each other at all times. They never touch or connect, this is a parallel wiring format.

Voltage

Every time a battery is added to the bank the voltage remains the same but the amp hours increase

So, you understand the basic layout of a battery bank connected in parallel, but the electrical principles are also worth understanding. Again, we can keep this simple.

Every time we add a battery to the bank the voltage remains the same but the amp hours increase by the size of the added battery.

Here, you can have a look at a real life example of this, as the batteries in our own Tiny Build Electrics example are wired in a parallel configuration.

Positive or Negative

The system above comprises of two individual 100ah lithium-ion batteries connected in parallel.

Here we have a total of 200ah at 12V. The common mistake here is to double the voltage and not the amp hours. In parallel the battery voltage remains constant and the amp hours increase.

Connecting your batteries in parallel is not just as simple as connecting all the reds and all the blacks. You also need to consider balancing the system.

How can you do this?

Instead of connecting both the positive and negative at one end of the bank via one battery, we connect the positive to the load at one battery bank and the negative to the load from the other end of the battery bank.

The diagram to the right depicts a battery bank correctly connected in parallel.

See how the negative has been taken from the last battery to the installation, whilst the positive has been taken from the first battery to the installation. The bank is now working as one unit. The current being drawn from the battery bank will now be equal across each battery and the bank will receive charge equally across all its batteries.

This way the charge and discharge is evenly spread throughout the entire battery bank. This way of wiring increases the likelihood that the manufactures specified life cycles will be met. If this is not adhered to you are in danger of damaging your batteries and depleting their lifecycles.

positive

Common mistakes when connecting batteries in parallel

When connecting your batteries in parallel you must balance your battery bank as discussed above. This is a crucial step and often overlooked during the installation stage.

This diagram shows a common way in which parallel battery banks are incorrectly connected. The way in which these are connected puts strain on the primary batteries and is considered unbalanced.

As you can see in the diagram the battery closest to the installation, let’s call this the primary battery, is the first in line to be discharged and is also the first to receive a charge current.

Each set of connecting cables, between each battery, creates a resistance. Electricity will always take the path of least resistance, like water flowing in a river. The path with the least resistance always wins. In the diagram shown, the primary battery is the first power source which has least resistance and therefore this one takes the biggest hit.

This will then happen in reverse when the battery bank is being charged. The primary battery gets a largest amount of charge current, with every set of interconnecting cables the charge current depletes from one battery to the next leaving the last battery with very little charge current.

Useful Definitions

Resistance: A measure of the opposition to current flow in an electrical circuit.
Charge Current: A flow of electrical charge carriers

Undercharged

Batteries in series

“In series the battery voltage increases and the amp hours remain the same”

Batteries wired in series are different. The principles are in reverse to a parallel setup. Instead of the voltage remaining the same and the amp hours increasing, the voltage increases and the amp hours remain the same.

Keep in mind, if you plan to wire multiple batteries together in series, each battery needs to have the same voltage and capacity and rating, or you can end up damaging the batteries.

This may seem irrelevant as I’m sure, like most people, you plan on having a 12v system in your camper van.
But, with older vans and vehicles becoming ever more popular to convert into tiny builds, their onboard electrical systems may surprise you.

A lot of big lorries and buses are being converted into tiny homes and they often have a 24V or 48V systems. Something to definitely bear in mind to ensure you purchase the correct equipment for your system.

To Installation

4 x 12v 100ah batteries in series 48V 100ah Battery Bank

Series & Parallel Wiring for Solar Panels

Each solar panel has a positive and a negative. A series connection is created when one panel’s positive is connected to the negative of another.

Both series and parallel wiring formats can also be applied to solar panel arrays. There are pros and cons to both methods. This is something you should consider carefully before starting your build.

When you wire multiple panels in series, their output voltages add together and their output currents remain the same. Conversely, when you wire numerous solar panels in parallel, their output currents add together, but their output voltages stay the same.

Series Solar Panel Wiring

Each solar panel has a positive and a negative. A series connection is created when one panel’s positive is connected to the negative of another.

Wire Diagram

Total Voltage: 22v x 3 = 66V
Total Current: 4.52A
Total Power: 300W

*These calculations do not include resistance losses caused by the panels and the cables. These numbers are for example purposes only.

From the calculation above you can see that the voltage has been multiplied by the three panels to give us 66v, the current remains at 4.52 amps. The total power (watts) is also accumulative of the three panels. This accumulates to 300w.

So, what are the Pros to wiring in this series over parallel?

Pros to series wiring format

  • Higher voltage gives the MPPT controller (maximum power point tracking) more range when adjusting its charge current.
  • MPPT Charger requires 5 volts more than the battery voltage in order to start charging. This works well with the series wiring as it creates a higher voltage and the charger is able to charge from earlier in the day and later into the evening extending the daily charge period.
  • On cloudier days the solar arrays output voltage is reduced, but due to the higher voltages produced by the series wiring format, the MPPT is still able to create a charge current. Whereas a parallel array would drop below the MPPT’s minimum PV voltage and switch off.
  • A lot simpler to wire
  • Uses less cable than parallel

Cons to series wiring format

  • If any shade covers even a single cell on a panel, it will reduce the whole system’s power output. For example parking under a tree will seriously impede your output charging current. In simple terms, the array likes to be balanced, it likes to see the same amount of light over every cell and when it gets this, its incredibly effective.
  • Each panel and every cell within that panel are critical in a series format.
  • Any spots of dirt over any of the cells will impede how the system charges. Therefore if your panels are in series they will need to be kept clean to maintain a optimum charge current. In series you cannot connect different size panels together. The power (watts) from the first panel passes through both the second and the third to make the accumulation, they all must be equal in size.
Gland Diagram

Two solar panels wired in series fitted to the top of a camper van.

The panels themselves have two cables each, so 4 cables altogether, but by connecting the positive of one to the negative of the other we essentially create one giant panel. That then leaves a positive from one panel and a negative from the other. These are the two cables we send down to the electrical control panel to connect to the MPPT controller. As seen this in the photo.

Parallel Solar Panel Wiring

A parallel connection is created when the positive of one panel is connected to the positive of another, and the negatives are connected to each other.

Dod Diagram

Total Voltage: 22V
Total Current: 4.52A x 3 = 13.56A
Total Power: 300W

*These calculations do not include resistance losses caused by the panels and the cables, These numbers are purely for example purposes.

From the calculation above the voltage now remains the same, a constant 22v. The current is 13.56A (that’s the current of each panel multiplied by 3).

A solar array in parallel is fantastic if partially shaded. In simple terms, if a few cells were covered by an overhanging tree, the rest of the array would pick up the slack and still give a reasonable charge current.

Pros to parallel wiring format

  • One of the biggest pros to wiring in parallel is you can mix different size solar panels together. If, up on top of your campervan or motorhome roof, you have fans, surfboards, wifi boosters and therefore only have room for a 100w, a 50w and a 25w, they can be configured in different orientations around your equipment. Although this can be done, we at TBE do not advise this as it is very inefficient.
  • When in optimal conditions parallel can give a very good, strong charge current.
  • When shade hits any part of a solar array wired in parallel, the power output from that panel reduces significantly. BUT, any other panels in the configuration are unaffected.

Cons to parallel wiring format

  • The parallel setup needs a certain amount of power from the solar panels in order to create a charge current.
  • During the winter months, when the sun is low in the sky, the parallel format will struggle to produce enough voltage to initiate a charge.
  • Requires a lot more cabling to wire a parallel format therefore your cable costs will be higher.
Solars

*These calculations do not include resistance losses caused by the panels and the cables, These numbers are purely for example purposes.

Real world results

MPPT Parallel
MPPT Series

These two screenshots above were taken on exactly the same day under the same conditions. The difference being that one set of panels is wired in parallel and the other wired in series.

The main difference you can see is that the parallel system has around 18v to optimise the best charge current, whereas the series system has between 28V-70V. So, in the example above, the MPPT has dropped the voltage to 29.38V in order to increase the charge current to 5.2A.

The parallel system is just about managing a charge current but its very weak.

Where the parallel system shines is if the solar panels were suddenly to become partially shaded by a tree, for example. The series system would dramatically reduce while the parallel would be little effected as the panel which isn’t partially covered is still able to produce its power, the series system requires all cells to be clear to effectively create a charge current.

If you plan to travel in all seasons then series solar wiring is the better format for those conditions with less sunlight. The series wiring combined with an MPPT controller maximises your chances of getting a healthy charge current even on those overcast days.

Although you may suffer more losses during the optimum operating conditions, series can produce a high enough voltage to charge the batteries from dawn to dusk.

If you travel in a camper van or motorhome that has a roof full of vents and fans and the only option is to fit panels in here, there and everywhere, then parallel will provide you with the option of having multiple, different sized panels together on your roof but remember, the panels need to have the same voltage to maintain efficiency.

Van

Diagram above demonstrating solar panels wired in series with a Victron Energy MPPT Controller

Our recommendations at Tiny Build Electrics

  • Wire your campervan solar setup in series.
  • Wherever possible, use the same size solar panels throughout the entire array.
  • If you must mix panels then try to get their specification as close as possible.
  • Pay attention to anything on your roof that could cast a shadow onto your solar panels, including maxxair fans, TV dishes and sports equipment.
  • Avoid parking in the shade or under trees to maximise performance.
  • Keep your solar panels really clean.
  • Use an MPPT controller when wiring in both series or parallel to maximise performance
Tom Alderdice

Hey, I’m Tom – founder of Tiny Build Electrics

My mission is to help sustainable-minded folks develop their electrical knowledge, giving them the confidence to do their own tiny build electrics.

Book A Consultation