Do i need a dc to dc charger for my camper? DC-DC Vs VSR. Features image
Electrics

Do I Need A DC To DC Charger For My Camper? DC-DC Vs VSR

Exploring the realm of campers and mobile homes brings many considerations, particularly in powering your journey’s comforts. A common query is, “Do I need a DC to DC charger for my camper?”

Whether you’re a newbie or a seasoned van-lifer, let’s look at your options and provide you with the information you need to make a well-informed decision.

In its simplest essence, you don’t absolutely need a DC to DC charger. Other split charging methods may suit your lifestyle and camper better.

However, having a DC to DC battery charger does offer many advantages for maintaining battery health and ensuring efficient charging. Imagine it as a ‘nice-to-have’ rather than a ‘must-have’, although the benefits are compelling enough to tilt the scales towards the former.

This article aims to provide a straightforward overview of the DC to DC charger – shedding light on its function and whether it’s a worthy addition to your camper setup.

A DC to DC battery charger will certainly prove a worthy investment. Done correctly, you will be sure that your batteries in your campervan will live a long and happy life.

This post may contain affiliate links. Meaning, if you make a purchase after clicking one, we may earn some commission. This pocket money will help Vandercamp Adventures continue to grow at no extra cost to you. It’s a win win situation!! Learn More…

Portrait photograph of Jolly sipping a coffee

Trust Me, I’m An Electrician

Jolly (a self-confessed electrical geek with over 17 years of experience as a qualified electrical engineer) carried out the product review and testing.

His focus now is campervan conversion electrics which started in 2019 with the birth of Vandercamp. Jolly is either building his own campervan or providing electrical help and guidance to others.

The Renogy 40A DC to DC charger is installed on his current campervan powering a Renogy 200Ah Lithium Leisure battery. 

Disclaimer

The information in this post is a combination of our knowledge, expertise and research. The content of the post is not sponsored. Therefore, all opinions are our own.

Do I Need A DC To DC Charger?

Unfortunately, there are many factors that will influence whether you need a DC to DC charger for your campervan. All will be covered in this blog post.

However, there are 3 reasons why you MUST use a DC-DC battery charger.

1) If you have a lithium-ion leisure battery

Because lithium batteries have low internal resistance, they draw high currents from the alternator. Unfortunately, alternators are not designed for high current draw so will burn out or even catch fire.

Therefore, a DC to DC battery charger is required to regulate the current.

2) If your vehicle has a smart alternator

Smart alternators are fitted to vehicles registered 2015 onwards. Referred to as Euro 5 & 6 engines. The output voltage of a smart alternator is controlled by the engine management system to reduce electrical and mechanical load on the engine.

The output voltage is variable because it will rise and fall depending on the engine condition.

Traditional vs smart alternator charge voltage graph
Information sourced from Redarc Electronics.

Smart alternators don’t sustain a charge voltage for periods of time so require a DC to DC charger to regulate the output voltage suitable for charging a leisure battery.

3) If the alternator is your only means of charging

If you rely on the alternator to charge your leisure battery, then you need to ensure it charges to 100%. Not doing so will affect the efficiency and lifespan of the battery.

Unfortunately, other split charging methods will only charge a leisure battery to approx. 80%. Because they don’t regulate their output voltage to suit the battery’s charging needs.

DC-DC chargers regulate an alternators output voltage to fully charge a leisure battery.

Other Reasons Why You May Need A DC To DC Charger

Regular driving in winter months

Compared to other split charging methods a DC to DC charger is better suited to charging your leisure battery if you regularly drive your camper in the winter months.

It will provide the most efficient charge for the battery even if it’s working alongside a solar system.

If you use your camper in winter

Winter months can be tough for charging a leisure battery. Even if you have solar panels there may not be enough energy to charge a battery enough for what you need, let alone 100%.

Therefore, a DC to DC charger can be used as a secondary charging method.

Why You May Not Require A DC To DC Charger

  • Budget Considerations
    While DC to DC chargers have their benefits, there are other split charging methods that might be kinder on your wallet. Look at our DC-DC charger price comparison table.
  • Space Constraints
    Installing a DC to DC charger requires not only space for the unit but also adequate ventilation. For those with cramped quarters, this might not be ideal. Explore our comparison table to see the best fit.
  • Robust Solar System
    Possessing an efficient solar system that can consistently charge your leisure battery to 100% throughout the year reduces the need for an additional charging method.
  • Regular Hook-Up
    For those who frequently stay at campsites or plug into shore power, mains charging emerges as the most effective way to juice up a leisure battery.
  • Non-Lithium Battery Types
    Those with open/closed lead-acid, AGM or GEL batteries might not find a pressing need for a DC to DC charger. Traditional split charge methods can suffice, though with somewhat less efficiency.
  • Sunny Climates Advantage
    In a sunny climate, your camper could have solar panels. The natural abundance of sunlight can sometimes negate the need for a DC to DC charger, as your battery receives a more predictable and direct charge.
  • Extended Summer Stays
    For individuals who predominantly use their camper during summer and settle in one campsite for extended durations, the battery demands charging even when stationary. In such cases, enhancing your solar system or relying on a mains battery charger could be more beneficial.
  • Short Distances, Less Drain
    If your adventures predominantly span short distances, and you’re not relying heavily on power-hungry devices, the drain on your leisure battery might be minimal. In such scenarios, a DC to DC charger might not be a priority.
  • Maintenance and Complexity
    For some, the idea of adding another component to their vehicle system can seem daunting. The more systems and components, the more there is to potentially maintain or troubleshoot.
  • Efficiency Isn’t Top Priority
    While a DC to DC charger can be more efficient, not everyone needs peak efficiency. Some are comfortable with a charging method that is “good enough”, even if it’s not the best.

Remember, the goal is to align your choices with your specific needs and circumstances. It’s always beneficial to assess and weigh up your unique situation against the potential benefits of any new addition to your camper.

What Is A DC To DC Charger?

Also known as a B2B, which stands for Battery-to-Battery charger, a DC to DC charger is known as the best split charging method for leisure batteries.

Think of it as a brainy electronic switch that’s strategically placed between the starter (the one in your vehicle) battery and the leisure or house battery.

While it might remind some of the functions of a voltage sensing relay (VSR), a DC to DC battery charger offers a more sophisticated approach. It boasts added features and superior benefits.

Its primary task is to convert the DC output power generated by the vehicle’s alternator, ensuring that the leisure battery is charged to its full 100%.

These chargers have found their way into various mobile settings, from campervans, RVs, boats to trucks and rugged off-road vehicles. Their versatility is commendable.

A DC to DC charger can stand as your primary charging source, serve as a backup, or operate alongside other power sources. They work well with the likes of solar panels, generators, and hook-up.

How Does A DC To DC Battery Charger Work?

Let’s break this down in a way that’s easy to understand, campervan electrics can get quite complicated at times.

Imagine your engine is like a big energy-making machine. When it’s running, it has this part called the alternator, which helps make electric power. This power first goes to the main battery (starter battery) of your vehicle. But, what about the extra battery that you might have to run other things in your camper, like lights or your fridge? That’s called a leisure battery.

Here’s where it gets tricky.

The energy made by the alternator isn’t always steady. It can change based on how you drive or how full the starter battery is. So, if we just use this energy, the leisure battery might not get charged properly.

Enter the DC to DC charger.

Think of it like a clever middleman. It takes the energy from the alternator and smoothens it out, making it just right to charge the leisure battery. This means the leisure battery gets the best and most efficient charge.

And there’s a bonus!

When you switch off your engine, and there’s no charging happening, this clever DC to DC charger makes sure the starter and leisure batteries are separate. Why? So, they don’t accidentally drain each other’s power.

How Does A DC-DC Charger Differ From Other Split Charge Methods?

Firstly, what are the other means of split charging?

  • Manual Switching – Simplest method. Manual On/Off switch to supply charge to the leisure battery.
  • Split Charge Relay – Connects the starter and leisure battery when the ignition is on.
  • Voltage Sensing Relay – Automatic switch that turns on when the alternator supplies the required output voltage.
  • Charge Splitter/Battery Isolator – Provides one way power flow to the leisure battery.

*This is a very brief overview of the different types of split chargers. Click here for more information

Basically, a DC to DC charger regulates the output power of the alternator to supply the battery with the voltage and current it needs. Whereas the other split charge methods use the fixed output voltage of the alternator to charge the battery.

A DC-DC charger uses a 3 stage (some models have 4 and 5 stage) charge process to provide the battery with the correct charge voltage and current to reach 100% capacity. The other split charge methods will only charge a battery to 80% because of the fixed voltage of the alternator. 

Leisure battery 3-stage charging chart
3-Stage Leisure Battery Charging

The Problem With Fixed Voltage Charging Leisure Batteries

Traditional 12v alternators are equipped with a standard internal regulator that delivers a charge voltage of 14 volts. The four split charge methods mentioned above use the alternators charge voltage (14v) to charge the battery.

Alternatively, a DC-DC charger takes the alternators charge voltage and delivers a three-stage charge (LINK) process to the leisure battery.

The completion of a three-phase charge sequence will ensure a battery reaches 100% charge. A traditional 12-volt alternator delivers a constant voltage of 14V that will charge a leisure battery but only to approximately 80% capacity.

Why?

Because the 14-volt charge voltage is too low to carry out the second phase of the three-phase charge process, the absorption phase. The “Absorption” phase requires a voltage of 14.4 volts. By not carrying it out, the battery won’t complete its charge cycle and reach 100% charge.

If the battery is frequently charged to 80% with no other means of charging to 100%, the battery will degrade, become less efficient and need replacing sooner. 

However, this can be overcome by using a mains/shore power charger or correctly designed solar charging system in addition to a split charging method.

Alternatively, use a DC to DC charger.

The Benefits Of DC To DC Charging – Compared To Other Split Charge Methods

  • Full Power
    Charges your leisure battery up to a perfect 100%.
  • Keeping Up with Modern Times
    Works great with smart alternators found in newer vehicles (2015 and beyond).
  • All Batteries Welcome
    Whether you’ve got lithium or another type, it’s got you covered.
  • Triple Care Charging
    Uses a 3-step method (bulk, absorption, and float) ensuring your battery lives a long and healthy life.
  • A Perfect Match
    No matter your campervans electric setup, it’s an ideal match for you.
  • Added Bonuses
    Some models come with fancy features like solar charging (MPPT) and two-way charging.
  • Safety
    Shields your system from unwanted events like too much voltage, high temperatures, and wrong connections.
  • Longer Battery Life
    By maintaining an optimal charge, DC to DC chargers can help extend the overall life of your leisure battery.

Downsides Of DC To DC Charging – Compared To Other Split Charge Methods

  • Expensive price range
    They can be a bit more expensive than other methods.
  • Size Matters
    DC to DC chargers need some room, not just to sit, but also to be well ventilated.
  • Things can go wrong
    With more electronics involved in the setup of the electrical systems, there’s potentially more that could go wrong.
  • Too many choices
    There’s a whole world of products out there. Picking the right one for your van can be a tad overwhelming. Check out the best DC to DC chargers for campers.
  • Technical installation setups
    Some of these chargers can be a bit technical when it comes to setting them up.
  • Power Consumption
    DC to DC chargers themselves use a bit of power to operate, which could slightly impact the overall power available for use.
  • Noise Level
    Some models may generate a small amount of noise during operation, which might be a concern for some users.

Installation Requirements

Installing DC to DC chargers is a process similar to other split charging methods. They’re wired between the starter battery and leisure battery. Requiring a positive and negative input from the starter battery and a positive and negative supply to the leisure battery.

Some units require ignition wiring to turn the charger on and off when the engine is on.

DC to DC charger wiring diagram to include input and output wiring and ignition wiring.

The only difference is they require more space to install, and they produce heat so require adequate ventilation to keep them cool.

Here’s a comparison table of the dimensions for the best DC to DC chargers for campers.

NameCharge Current (Amps)DimensionsView
Renogy DCC12-12-20/40/60Renogy 40A DC-DC charger20A
40A
60A
(10/30)*
211x175x68
261x175x68
311x175x68
View Product
Renogy REGORenogy REGO 60A DC to DC battery charger 10-60354-213-102View Product
Victron Orion-Tr SmartB2B/DC-DC leisure battery charger18
30**
130x186x70
130x186x80
View Product
Redarc BCDC 1225D, 1240D, 1250DRedarc BCDC1240D 40A DC DC Charger MPPT Solar Controller25
40
50
165x120x37View Product
CTEK D250 SECTEK D250SE DC to DC battery charger20A***192x110x65View Product
Sterling BB1230, BB1260Sterling BB1230 DC to DC charger30
60
190x160x50
198x164x71
View Product

See the full comparison table.

NOTE:

Always read the manual and check out the specification before purchasing a DC to DC charger.

Even though they’re very similar, they all have their unique differences. Check out our comparison table for an overview.

Why Do We Have A DC To DC Charger?

We use our DC to DC charger as a secondary or backup charging method to our solar installation.

Renogy 40A DC to DC battery charger
Our Renogy 40A DC-DC Battery Charger

Our solar installation provides enough power to ensure we have sufficient charge in the battery for most of the year.

However, winter months can be tough for solar energy. Therefore, we rely on the DC-DC charger to top up the battery to ensure it gets a 100% charge regularly.

Our DC to DC charger features an on/off switch, allowing us to use it only when necessary. This helps prevent any undue strain on the alternator when charging isn’t required.

Our DC To DC Battery Charger Setup

We have a Renogy 40A DC to DC battery charger supplying a 200Ah Lithium-ion leisure battery.


We only use the charger when necessary to top up the leisure battery. To easily identify whether the charger is on or off, we have installed an illuminated ignition switch on the dashboard.

To avoid overloading the alternator, we allow it to charge the starter battery and supply power to the vehicle electrics before the DC-DC charger draws a charge current.

To achieve this, we use a time delay relay. This device delays the operation of the DC to DC charger, even if the ignition switch is on. For instance, if the switch is on during start-up, the charger only turns on when the timer on the relay runs out.

Further Reading | Why We Chose The Renogy DC-DC Battery Charger

Additional DC To DC Charger Features

DC to DC chargers come packed with a variety of advanced features, enhancing their functionality, and offering users a more comprehensive experience.

Let’s explore some of the most standout features that some DC to DC chargers have to offer.

Bi-directional Charging

Imagine a scenario where your leisure battery has a full charge, yet there’s energy to spare. Bi-directional or two-way charging steps into the spotlight here. It gracefully diverts any excess power back to the starter battery.

CTEK D250SE DC to DC battery charger
CTEK D250SE With Bi-directional Technology

A dual input DC to DC and Solar charger with this feature ensures no ray of solar energy goes to waste.

And for those moments when you’re parked up and soaking in nature? You can have the peace of mind that your starter battery is kept company with a steady charge.

Dual Input (DC-DC + Solar)

In the campervan world, efficiency is king. And DC to DC chargers with built-in MPPT charging are steadily wearing the crown. This awesome technology, often found in solar charge controllers, facilitates charging of the leisure battery through both the alternator and solar power – all within a single unit.

Renogy DCC50S DC to DC charger with MPPT Solar
Renogy DCC50S DC-DC and Solar MPPT charger

They’re gaining popularity in campervan conversions and it’s easy to see why. Their cost-effectiveness is a clear winner. Add to that the benefits of saving space, shedding unnecessary weight, and the ease of a quick installation.

However, like all prized possessions, they have their unique quirks. For a deeper dive into DC-DC + Solar MPPT charging, explore here.

Bluetooth Connectivity

In an era where technology sits comfortably in our pockets, why should your DC to DC charger fall behind?

B2B/DC-DC leisure battery charger
Victron Orion TR-Smart with Bluetooth connectivity

Consider chargers with Bluetooth capabilities. These contemporary devices connect effortlessly to your gadgets. This connection allows for a smooth setup and offers real-time monitoring through specific apps.

Take the Victron Orion-TR Smart, for instance: it pairs delightfully with the Victron app, transforming your phone or display into a vigilant monitor for your charging needs. Discover more here.

Alternatives To DC To DC Charging

There are 4 other methods of charging a leisure battery in a campervan.

  • Hook up/Shore
  • Solar
  • Generator
  • Wind

These charging methods can be used on their own or together for a more efficient way of charging your leisure battery.

This overview just skims the surface. For a deeper dive into battery charging, explore our detailed blog post: “5 ways to charge a leisure battery”.

Hook Up/Shore Power

Hook up/shore power is the best method of charging a battery to 100%. Simply plug into the mains and let the charger do the rest. However, you always need a mains supply, which can restrict your travels.

mains power leisure battery charging

A DC-DC charger is an efficient addition to hook up because it can be used to charge the battery between hook up charges, to ensure you have enough power. Therefore, not relying on the DC-DC charger to charge the leisure battery to 100%.

Discover more about hook up/shore power charging

Solar Power

Solar power is the most eco-friendly and efficient way of charging a leisure battery, and it’s free. It will charge if there is daylight, whether you’re driving or parked up. Therefore, a correctly designed solar system will ensure your leisure battery is charged to 100% capacity.

Wind turbine leisure battery charging

However, during months when the sun is low (winter) and at night there is minimal to no solar charge.

A DC-DC charger can be used as a secondary/backup charging method to solar power. It can be used to top up the battery when solar energy is low, during winter months and to ensure the leisure battery gets regular 100% charge.

Discover more about solar power charging.

Wind Power

Wind power, like solar, its eco-friendly, efficient, and free. Wind rotates a turbine to generate power. However, a turbine cannot be permanently fixed to the van so must be erected and dismantled every time you stop and require power.

Wind turbine leisure battery charging

Also, you need wind and just the right amount, wind turbines are very sensitive creatures.

A DC-DC charger can be used alongside wind power. Wind is unpredictable, especially in the UK. Therefore, a DC-DC charger can be used as a primary charging method, harnessing wind energy when it’s available.

Discover more about wind power charging.

Generator

Generators are a great way to charge a leisure battery if you plan to go into the wild. They don’t need a mains supply, sunlight or wind so will work in any environment, if you have fuel. They’re very efficient and compact.

Generator leisure battery charging

However, they’re noisy and pump out fumes into the environment.

A DC-DC charger is a great addition to generator charging for when the environment isn’t suitable for using a generator (E.g. built up areas).

Discover more about using a generator to charge a leisure battery.

Further Reading | How To Charge A Leisure Battery In 5 Ways

Our Honest Opinion of “Do I Need A DC To DC Charger For My Camper?”

If you don’t NEED a DC to DC charger because of the reasons detailed above, we think it’s still a worthwhile investment.

Even if you have all the requirements to charge your battery to 100% without a DC to DC charger there will be times where your battery needs a top up, especially in winter.

For example, we have enough solar power to keep us fully juiced most of the year. However, in January and February, solar energy is at its lowest, so we rely on the DC to DC charger to top up our lithium battery.  

Relying solely on a DC to DC charger can strain your campervan’s alternator. A well-chosen charger will do its job, but pushing the alternator too hard can shorten its life. Keep in mind, a worn-out alternator results in a broken-down van and can be expensive to replace.

So, when setting up your electrical system, think about the long-term health of all components.

Best use of a DC-DC charger is for a secondary/backup charging method to solar. Solar produces more power for the money. Therefore, it’s better to install a solar system to your campervan or increase or upgrade the solar system you have.

 If your budget is low, consider a combined DC-DC + Solar charger.

FAQ’s

What Size DC To DC Charger Do I Need?

Figuring out the right size for your DC-DC charger can be influenced by several factors. Your starting point? Knowing the maximum DC to DC charge current your camper can handle.

If you’re looking for a helping hand, our step-by-step guide with calculators is just the thing you need.

Will A DC To DC Charger Drain My Starter Battery?

The good news is, when your DC-DC charger isn’t actively charging, it disconnects both the starter and leisure battery, preventing one from draining the other.

However, be cautious if your DC-DC charger needs an ignition wire; incorrect wiring could lead to unnecessary power drain. Need more info?

Our guide on Renogy DC-DC charger ignition wiring is a must-read.

How Many Amps Does A DC To DC Charger Draw?

The answer hinges on your charger’s output current. Remember, while chargers have amp ratings indicating the output, they’ll draw more due to their own operational needs.

For instance, the Renogy 40A DC-DC charger operates at over 90% efficiency. This means it needs to draw at least 44 amps to supply a 40-amp charge.

Can I Swap A VSR For A DC To DC Charger?

Absolutely! Think of the DC-DC charger as the sophisticated cousin of the VSR. They can replace any split charge unit, but you must ensure the existing cables can handle the current.

Also, DC-DC chargers require more space and proper ventilation.

How Quickly Will A DC To DC Charger Juice Up My Leisure Battery?

The charge speed is directly related to the charge current: the higher the current, the quicker the charge.

However, don’t forget to account for your camper’s max charge current. Curious about specific recharge times? Dive into this detailed article.

Is A DC To DC Charger Compatible With Solar?

Indeed! While split charging and solar charging can function as independent methods, they can also work in tandem to charge your leisure battery. Some units even combine both features for optimal charging.

If solar energy is low, a DC-DC charger can serve as a backup. Intrigued about the duo of DC to DC and solar?

Discover the benefits of combined charging.

RECAP

In our article of “Do I Need A DC To DC Charger For My Camper?“, we’ve explored` the realm of charging solutions for campers. This vital choice can have lasting implications for your camper’s battery health and efficiency.

The DC to DC charger, while being a more modern and sophisticated tool, offers a multitude of benefits over traditional VSRs. DC to DC chargers offer efficient charging, compatibility with newer vehicles, and varied battery support.

On the flip side, they are costlier, require more space and may seem complex to install. However, with the ever-evolving technology, their enhanced features can elevate your camping experience.

So, to answer the question, Do I Need A DC to DC Charger For My Camper? its ultimately down to you.

We hope that the guide has helped you through your decision-making process for your camper’s electrical system.

If you decide a DC to DC charger is right for you, here are some useful articles to help you on your way.

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