[Full Guide] What is a DC To DC Charger?

DC to DC charger

When it comes to powering electronic devices, having a dependable and efficient energy source is essential. DC to DC chargers, also known as DC-DC converters, are integral in transforming one voltage level to another within direct current (DC) systems. This article explores the operation and uses of these chargers, highlighting their advantages and the ways they enhance power conversion across a variety of devices and systems.

What is A DC to DC Charger

A DC to DC battery charger is a device that utilizes the charging current from a vehicle's alternator to recharge a separate deep cycle battery while driving. This enables users to conveniently recharge their RV or van battery on the go. The charger boosts the charging current from the alternator and directs it to the auxiliary battery, effectively utilizing the power generated by the vehicle's engine. This functionality provides a convenient and efficient solution for maintaining battery charge during trips.

DC, or Direct Current, is a type of electrical current that flows in a single, constant direction, as opposed to AC (Alternating Current), where the flow of electrons reverses direction periodically. DC current is commonly used in batteries, solar panels, and electronic devices that require a steady flow of current in one direction.

A DC to DC charger, also known as a DC-DC converter or voltage converter, is an electronic device used to convert one voltage level to another within a direct current (DC) system. It finds applications in various fields such as automotive, solar power systems, telecommunications, and industrial equipment.

The DC to DC charger takes an input voltage from a DC power source, like a battery or power supply, and efficiently converts it to a different output voltage level required by a particular device or system. It provides regulated and stable DC power, ensuring compatibility and protecting sensitive components from voltage fluctuations.

battery size chart

The primary function of a DC-DC charger is to convert a lower voltage current into a higher voltage to charge a secondary battery. It follows a multi-stage process—bulk, absorption, and float—to efficiently charge the battery.

Why Do You Need a DC-DC Charger?

First, we should know the differences between RV starting battery and housing battery.

The Differences Between RV Starting Battery and Housing Battery

The primary distinction between an RV starting battery and a house battery, also known as a service battery or deep cycle battery, lies in their specific functions and design attributes.

Starting Batteries:

Starting batteries are engineered to deliver short bursts of high power to start the RV's engine. They are typically measured in cranking amps (CA) or cold cranking amps (CCA) and are designed to provide a large amount of current for a brief period. These batteries have a high CCA rating to meet the demands of engine startup, but they are not suitable for deep cycling, which involves frequent discharging and recharging.

House Batteries (Deep Cycle Batteries):

House batteries, also referred to as deep cycle batteries, are intended to provide a steady and reliable flow of power over an extended period. These batteries are designed for regular discharging and recharging without negatively impacting their overall lifespan. They are optimized for deep cycling and feature thicker plates that can withstand repeated discharges. House batteries are usually rated in amp-hours (Ah) or reserve capacity (RC) and supply a consistent power source for RV appliances, lighting, and other electrical systems.

Key Differences:

1. Purpose:

  • Starting Batteries: Deliver high bursts of power for engine startup.
  • House Batteries: Designed for deep cycling and supplying power over longer durations.

2. Design:

  • Starting Batteries: Have higher CCA ratings and thinner plates, making them ideal for short-term high power output.
  • House Batteries: Feature thicker plates and are built to endure repeated discharges and recharges, suitable for long-term energy supply.

3. Rating:

  • Starting Batteries: Rated in cranking amps (CA) or cold cranking amps (CCA), emphasizing their ability to start engines.
  • House Batteries: Rated in amp-hours (Ah) or reserve capacity (RC), focusing on their capability to provide sustained power over time.

The Purpose of A DC-DC Charger

The purpose of a DC-DC charger is to effectively charge your house batteries by converting the output from your primary battery, ensuring that it matches the specific charging requirements of the house batteries, which differ from those of lead-acid batteries. The DC-DC charger functions as the control unit, guiding your alternator on how to properly charge your house batteries.

DC (direct current) is characterized by a constant voltage flow and is widely used for its efficiency, especially in smaller vehicles like cars, boats, and vans. DC-DC chargers have gained significance in the context of solar power in vans, as they facilitate the conversion and storage of power in secondary batteries. This power can then be used for various applications, ranging from charging cellphones to running major appliances like refrigerators. For van lifers who are frequently on the move, a DC-DC charger efficiently charges the secondary battery, enabling you to power your appliances while traveling.

How Does a DC-DC Battery Charger Work?

A DC-DC battery charger is a device that allows you to charge one battery from another battery, even when they operate at different voltage levels. It accomplishes this by converting the input voltage from the source battery to the appropriate output voltage required for charging the target battery.

The charger includes several key components: a DC-to-DC converter, control circuitry, and sometimes a voltage regulator. The DC-to-DC converter is responsible for adjusting the voltage, either increasing (stepping up) or decreasing (stepping down) it as needed. This voltage conversion often employs switching techniques such as pulse width modulation (PWM) or buck-boost converters.

The control circuitry plays a crucial role in monitoring the charging process, adjusting the voltage and current as necessary to ensure efficiency and safety. Many DC-DC chargers also feature built-in battery management systems (BMS) that protect the batteries from overcharging, over-discharging, and other potential issues.

The charger typically offers various charging modes, including bulk charging, absorption charging, and float charging. These modes optimize the charging process according to the specific requirements of the target battery, ensuring it is charged efficiently and properly.

In essence, a DC-DC battery charger facilitates the transfer of power between batteries with different voltage levels, effectively charging the target battery while maintaining the necessary charging parameters for safety and efficiency.

The Benefits of Using a DC-DC Charger

There are several benefits of using a DC-DC charger:

Efficient power conversion

DC-DC chargers are engineered to convert the voltage from one direct current (DC) source to another, optimizing power conversion efficiency. This ensures that minimal power is lost during the charging process, allowing for more energy to be effectively transferred to the battery.

Compatibility with different voltages

DC-DC chargers are frequently adjustable, enabling them to accommodate a range of input and output voltage levels. This adaptability allows them to be compatible with different battery types and sizes, as well as various power sources like solar panels and vehicle batteries.

Protection features

Many DC-DC chargers are equipped with built-in protection features, such as over-current protection, over-voltage protection, and reverse polarity protection, to safeguard the batteries from potential damage. These safety measures not only enhance the reliability of the charging process but also extend the lifespan of the batteries.

Flexibility and versatility

DC-DC chargers are versatile and can be used for a wide array of applications, ranging from charging small electronic devices like smartphones and tablets to powering larger appliances such as refrigerators and televisions. They are particularly useful in off-grid environments or during outdoor activities where access to conventional power sources is limited.

Faster charging times

DC-DC chargers often deliver faster charging times compared to other methods. This is particularly beneficial for devices with high-capacity batteries, where charging from a low-voltage source can be significantly slower. DC-DC chargers are engineered to optimize the charging process, enabling quicker recharge times.

Increased battery life

DC-DC chargers are engineered to deliver precise and controlled charging currents, effectively extending the lifespan of batteries. By providing accurate voltage and current levels, they prevent overcharging or undercharging, which are common causes of battery degradation.

In summary, employing a DC-DC charger ensures enhanced efficiency, flexibility, and protection during battery charging, establishing it as a preferred option across various applications.

Can I Use a DC-DC Charger with Lithium Batteries?

Certainly! DC-DC chargers can indeed be used with lithium batteries. They are commonly employed for charging both lithium-ion and lithium-polymer batteries. DC-DC chargers are often preferred for charging lithium batteries because they offer a stable and precisely controlled charging process. With the adjustable voltage and current settings of a DC-DC charger, you can safely and efficiently charge lithium batteries. It's important to adhere to the manufacturer's guidelines and recommendations for charging lithium batteries to ensure their longevity and safety.

What Size DC-DC Charger Should You Get?

The standard DC-DC charger typically comes in capacities of 20A, 40A, and 60A.

Selecting the correct size DC-DC charger depends on several factors. For batteries up to 200Ah, a charger with around 25A capacity is suitable. For larger battery capacities exceeding 200Ah, a 40A DC-DC charger would be more appropriate.

Consideration of your alternator size is crucial. If your alternator is rated at 200 amps, it's advisable to use a charger with half that capacity (100 amps) to prevent overloading the alternator.

The type of battery you have also influences charger sizing. For standard batteries like AGM and lead-acid, a DC-DC charger rated at 20% of the battery's amperage is adequate. However, for lithium batteries, you can opt for a charger up to 30% of the battery's rated amperage.

Matching the charger voltage with your electrical system is essential. For instance, if your system operates at 12 volts, a 12-volt DC-DC charger is appropriate.

Lastly, consider your energy consumption and the number of appliances powered by your auxiliary battery. Multiple appliances may require a DC-DC charger with higher capacity.

dc to dc battery size

Always refer to the manufacturer's specifications and recommendations to ensure the correct DC-DC charger selection for your specific setup.

Where To Install A DC-DC Charger

The installation location of a DC-DC charger depends on the specific vehicle and setup. Typically, it's advisable to install the DC-DC charger near the vehicle's starting battery and alternator to minimize voltage drop and enhance charging efficiency.

Ensure the installation site is well-ventilated, cool, and dry. The charger should be positioned away from direct sunlight, high temperatures, and water exposure. Allow sufficient space for wiring and provide adequate ventilation clearance above and below the charger, ideally at least 2 inches (5cm).

Install the charger as close as possible to the battery you intend to charge (service battery). It can be mounted either as a stand-alone unit or wall-mounted, offering flexibility in horizontal or vertical orientation. Vertical mounting is preferable for optimal cooling performance.

Dual Input DC TO DC Battery Charger With MPPT

Dual input DC to DC battery charger has many advantages than other stander DC DC charter.

Features of 12V 40A DC-DC Battery Charger

The DC-DC charger stands out for its MPPT charging capability, allowing it to effectively utilize solar power for battery charging, making it ideal for off-grid or remote locations.

In addition, this charger features a reverse charging function, enabling your house battery to charge the starting battery during emergencies, ensuring readiness in challenging situations.

Equipped with a display screen and user-friendly buttons, the DC-DC charger provides clear insight into battery charging status and enables direct adjustments to battery modes, offering unmatched control and flexibility over the charging process.

Designed for customer convenience, the DC-DC charger adopts a plug-and-play design for straightforward connection and use, eliminating the need for complex installation procedures or technical expertise.

Compatible with various 12V battery types including Lithium, Gel, AGM, and Calcium, the charger ensures 100% charging capability across these battery types and can even revive depleted lithium batteries with low voltage.

With a maximum power input of 600W and a current output of 40A, the DC-DC charger features essential terminals such as ACC wire, solar input, DC input, and output terminals, enhancing the operational efficiency of solar panels, alternators, starting batteries, and service batteries.

Safety is prioritized with the DC-DC charger, equipped with intelligent charging protections including reverse input, overvoltage input, output reverse connection, battery overvoltage, over-temperature, charging timeout, and BMS protection for Lithium Iron Phosphate (LFP) batteries, ensuring reliable and secure operation.

Is Dual Input DC TO DC Battery Charger Suitable for You?

If you have or are planning to install solar panels on your RV or van and aim to maximize charging current from your alternator to charge your house battery while driving, the Dual Input DC to DC Battery Charger is an ideal solution. This charger functions as both a battery isolator/charger and a charge controller, seamlessly integrating into your existing system by replacing the current charge controller.

It is particularly beneficial if you need to charge an auxiliary battery in your van or truck that powers specific equipment like a fridge or tools. Moreover, if you use a Folding Solar Suitcase without a built-in charge controller during non-driving times, this charger can efficiently handle battery charging.

For travelers in regions or seasons with limited sunlight availability, the Dual Input DC to DC Battery Charger offers added charging current from your alternator, providing a valuable supplement during extended boondocking sessions without requiring additional solar panels.

In summary, the Dual Input DC to DC Battery Charger is a versatile and dependable solution that maximizes the efficiency of your solar panels and alternator, ensuring effective battery charging across diverse scenarios.


Now equipped with this information, you can confidently make a well-informed decision and choose the ideal DC-DC charger that aligns perfectly with your requirements.