Isolated vs Non-Isolated Converters and DC-DC Chargers: A Comprehensive Guide

What are Isolated DC-DC Converters and DC-DC Battery Chargers?

Isolated converters and DC-DC chargers are power conversion devices designed to create a physical separation between the input and output power, providing an 'isolation barrier' that helps manage electrical noise and radio frequency interference (RFI). This makes them ideal for sensitive applications.

Key Features of Isolated DC-DC Converters and Chargers

Some of the key features of isolated DC-DC converters and chargers include:

• Elimination of ground loops
• Protection against voltage spikes
• Improved safety due to isolation barrier
• Reduced noise and RFI

Advantages and Disadvantages of Isolated DC-DC Converters and Chargers

Isolated converters and DC-DC chargers offer several advantages:

• Safety: The isolation barrier protects against electrical shocks.
• Noise reduction: They are excellent for reducing electrical noise and RFI, crucial in sensitive applications.
• Versatility: These converters can be used to step up or step down voltages.

However, they come with some disadvantages:

• Cost: They are generally more expensive than non-isolated converters.
• Size: Due to the need for an isolation barrier, they tend to be larger.

What are Non-Isolated DC-DC Converters and Chargers?

Non-isolated converters and DC-DC chargers, on the other hand, do not provide a physical separation between the input and output power. This makes them more compact and cost-effective, although they lack the noise and RFI reduction capabilities of their isolated counterparts.

Key Features of Non-Isolated DC-DC Converters and Chargers

Non-Isolated converters and DC-DC chargers are characterized by:

• Compact size
• Cost-effectiveness
• Ability to step up or step down voltages

Advantages and Disadvantages of Non-Isolated DC-DC Converters and Chargers

Non-Isolated converters and DC-DC chargers offer several benefits:

• Affordability: They are typically less expensive than isolated converters.
• Compactness: Their lack of isolation barrier means they can be made smaller, suiting space-constrained applications.

However, their drawbacks include:

• Noise and RFI: They may not adequately manage electrical noise and RFI, which can be a problem in sensitive applications.
• Limited functionality: They are typically limited in how high they can step up voltages.

Choosing Between Isolated and Non-Isolated DC-DC Converters and Chargers

When deciding between isolated and non-isolated converters and DC-DC chargers, it's important to consider your specific needs. If managing electrical noise and RFI is crucial, or you need a converter to step up voltages, an isolated converter might be the best option. However, if cost and size are your main concerns, a non-isolated converter could be your ideal choice.

Isolated and Non-Isolated DC-DC Converters/Chargers for Marine, Off-Grid, and RV Applications

When it comes to power management in diverse environments such as marine vessels, off-grid homes, and recreational vehicles (RVs), the role of DC-DC converters and chargers is crucial. Both isolated and non-isolated variants provide key solutions for maintaining steady, safe, and efficient power supply, with each type offering unique benefits.

Marine Power Systems

In the challenging marine environment, isolated DC-DC converters and chargers truly shine. Sea vessels often face high levels of electrical noise and radio frequency interference (RFI), potentially affecting the performance of sensitive onboard electronics such as navigation and communication systems. Isolated converters, with their ability to manage electrical noise and RFI, ensure the reliable operation of these critical systems. Renowned brands like Victron offer robust, marine-grade isolated converters designed for these demanding conditions.

Off-Grid Power Solutions

For off-grid living, the choice between isolated and non-isolated converters largely depends on the specifics of the home's energy system. If the system involves high-voltage photovoltaic arrays or wind turbines, isolated converters provide a necessary safety barrier and flexibility for managing different voltages. However, in more streamlined low-voltage systems, non-isolated converters may be more practical, offering cost-effectiveness and space efficiency.

RV Power Management

In the RV space, both isolated and non-isolated converters find their niche. For those venturing to remote areas with unstable or noisy power grids, an isolated converter can ensure seamless operation of appliances and devices within the RV. Conversely, for occasional RV users or those staying in well-serviced areas, a non-isolated converter may suffice, providing a dependable power supply at a lower cost.

Buck, Boost, and Buck-Boost Converters

Buck converters, also known as step-down converters, are advantageous when the input voltage is higher than the output voltage. They are often found in battery-operated devices and solar power systems. Boost converters, as the name suggests, step up the input voltage to a higher output voltage. Buck-boost converters, the most versatile of the three, can either step up or step down the voltage as needed, making them ideal for a wide array of applications including electric vehicles, power backup systems, and more. 

Wiring Considerations for DC-DC Converters/Chargers

When installing DC-DC converters and chargers, proper wiring is essential for both safety and efficiency. A critical aspect to consider is the use of 3-wire non-isolated converters/chargers. These devices have a common negative, therefore only 3 wires, Starter Battery Positive Input, Common Ground (both batteries negatives must be joined), and House Battery Output.  Most 12V and 24V in caravans and almost certainly in 4x4 and van systems have common grounds.  However 48V is often isolated, therefore an isolated converter / charger may be required.

The distance to the batteries also plays a vital role. Longer cable runs can lead to voltage drop, negatively impacting the charger's efficiency and the overall performance of the power system. To mitigate this, it's crucial to use appropriately sized cables. Using cables that are too thin for the current they carry can result in excessive heat and potential fire hazards. On the other hand, excessively thick cables can be costly and difficult to install.  Always install the converter / charger close to the load or house battery for optimal voltage stability.

Always fuse cables at both batteries.  If the charger is rated at 30A (meaning 30A output), often it will draw around 33-35A due to efficiency losses.  As you do not want to use a fuse too small, both to avoid nuisance tripping and to avoid overheating of the fuse, a minimum of 50A would be required.  

Consider consulting an online cable sizing guide or a professional electrician to determine the appropriate cable size for your specific setup. Brands like Victron and Enerdrive also provide installation manuals with their products, offering further guidance on these crucial considerations.

The Best Choice

Both isolated and non-isolated converters and DC-DC chargers have their unique strengths and weaknesses. The best choice will depend on your specific needs, whether they be reducing electrical noise and RFI, managing cost and size, or the ability to step up or down voltages. Always consider these factors carefully when making your decision.

Explore Our Range of Converters and DC-DC Battery Chargers

At Solar 4 RVs, we offer a wide range of isolated and non-isolated converters and DC-DC chargers, including popular brands like Victron and Enerdrive. Browse our selection today to find the perfect solution for your power conversion needs.