3 of the Best 12v DC to DC Battery Chargers

At first glance, using a DC to DC battery charger might seem redundant. Why not just charge directly from your power source? There are a couple of reasons for this, and the first is a multi-battery vehicle setup. If you’re trying to keep your backup battery charged, it can be very difficult on a modern vehicle. The reason for this is that modern “smart” alternators will shut off when the primary battery is full. By wiring your secondary battery to your primary via a DC to DC charger, you avoid this problem. You can also position the backup battery anywhere in the vehicle, regardless of the alternator location.

As an added bonus, DC to DC chargers provide a steady current. Instead of an alternator’s fluctuating current, they will always provide what your battery needs. This reduces wear and tear on your electrical system, noticeably improving the life of your battery.

The other reason you might want to use a DC to DC battery charger is for a solar power system. Sure, you can charge off-grid deep-cycle batteries directly from most solar panels. But if you do this enough times, you’ll run into the same longevity issues as charging from an alternator. A DC to DC charger can keep your off-grid system running smoothly. When you go back to your cabin after weeks of absence, you’ll still have plenty of power.

Today we’re going to review three of the best DC to DC battery chargers on the market. First up, we’ll look at the Victron Energy Orion-Tr Smart DC-DC Charger. This is a compact automotive charger that can output up to 360 watts at 30 amps. Next, we’ll examine the Renogy DCC50S 12V 50A DC Board Battery Charger. This is a more powerful 600-watt, 50-amp charger for larger vehicles and solar arrays. FInally, we’ll review the REDARC BCDC1225D. This 25-amp charger is specifically designed for off-roading and other demanding applications. Which DC to DC charger is the best? To find out, we’re going to have to dig deep into their features, benefits, and drawbacks. After that, we’ll be able to render our verdict.

12v off grid solar system

Features to Look For in a DC to DC Charger

So, what makes one DC to DC charger better than another? In many respects, it depends on what you need. That said, there are several important features to take into consideration when you’re shopping. To begin with, a quality charger should be versatile. Can you connect to the alternator? The battery? Depending on exactly what you’re trying to achieve, it makes a big difference. Not only that, but you should also look for solar compatibility, even if you don’t need it today. Solar cells and panels continue to get cheaper year after year. The day may soon arrive where attaching a small solar panel is so affordable that everyone does it. Solar panels also allow you to keep your battery charged when your car or RV isn’t running.

Charging power is also an important consideration. Different automotive batteries have wildly different amp-hour capacities. Not only that, but other batteries, like deep cycle marine batteries have even more different capacities. A charger that’s too weak will not charge the battery efficiently. A charger that’s too strong, on the other hand, can cause cells to prematurely become damaged. This increased wear and tear can greatly reduce the lifespan of your battery. In other words, a more powerful charger is not necessarily better! It needs to be matched to your battery in order to get the best results.

Many chargers will adjust their output depending on your battery’s needs. Many can even adjust to different types of batteries, such as lithium-ion or absorbent glass mat (AGM). The more flexible your charger is, the less you’ll have to worry about battery compatibility.

Similarly, you want a charger that’s catered to your purposes. Some chargers are designed for heavy-duty use, such as in vehicles that are used daily. On the other hand, you may want a trickle charge more often than not. A compatible DC to DC charger can keep a motorcycle or boat battery topped up over the winter. It can also keep a classic car battery fully juiced between auto shows. These types of chargers tend to be smaller, since they don’t need to handle such constant abuse.


Depending on your conditions, you may need your charger to work at very low or very high temperatures. Keep these ratings in mind while you shop. A charger needs to be built very differently to survive in Fairbanks, Alaska versus Las Vegas, Nevada. Even for people in temperate climates, high heat can be a concern for automotive chargers. The area under your hood can get very hot, even on a mild day. This can also vary depending on how you drive. If you’re off-roading or doing city driving, there will be less airflow and your engine compartment will be hotter. If you’re on the highway most of the time, the increased air flow will keep the compartment proportionally cooler.

Finally, a good DC to DC battery charger should have easy-to-read lights and indicators. This might seem like a purely cosmetic concern, but it’s not. When you’re bent over your engine at an awkward angle, fiddling with wires, you’ve got enough to handle. The last thing you need to worry about is trying to decipher whether or not the charger is properly connected. You should also be able to see the fault status at a glance. Some chargers make this easier by including a smartphone app. This allows you to monitor your charger status without opening up the hood. Even so, smartphone control is more of a convenience than a necessity. The main thing is that it’s easy to understand what’s going on during installation.

Victron Energy Orion-Tr Smart DC-DC Charger

Victron Energy Orion-Tr Smart DC-DC Charger

The Victron Energy Orion-Tr Smart DC-DC charger is a great choice for light to medium-duty applications. It’s built into a sturdy steel frame that’s designed to be bolted down for installation. The overall dimensions are 7.32 inches in width, 5.12 inches in depth, and 2.76 inches in height. Much of this height consists of the frame, so the actual unit is a bit smaller. At 3.96 pounds, it’s lightweight and won’t add any significant extra weight.

The Orion-Tr is a smart charger, so it will automatically detect what type of battery is connected. It can be used with lead acid and lithium batteries without the need to change any settings. The overall maximum power output is 360 watts and 30 amps. However, that can be increased by running multiple chargers in parallel. There’s no reason to do this for automotive purposes, but it’s very effective for solar arrays. Moreover, the Orion-Tr accepts anywhere from eight to 17 volts of input. This makes it useful for alternators, solar panels, and other highly-variable power sources.

Victron Energy Orion-Tr Smart DC-DC Charger

One neat thing about the physical design is the screw terminals. They require only a simple standard screwdriver, so they’re easy to connect and disconnect. You don’t have to use any special tools that aren’t already in your toolbox. The terminals are all clearly marked, so they’re easy to read. There are also indicator LEDs to let you know when the charger is active, as well as when Bluetooth is active.

Yes the Orion-Tr has Bluetooth. Once it’s plugged in, you can install the Victron Energy app on your phone and control it wirelessly. Through the app, you can program your charger and monitor its status. You can also install a wired remote for a simple dashboard on/off switch.

Renogy DCC50S

Renogy DCC50S 12V 50A DC Board Battery Charger

Renogy is a well-known manufacturer of power systems. We recently reviewed some of their 100-watt, 12-volt solar panels, and we were impressed. So we were eager to find out whether the Renogy DCC50S 12V 50A DC Board Battery Charger meets that standard.

The DCC50S is a bit larger than our first choice, at 9.6 inches wide, 5.7 inches deep, and 3 inches thick. Like the Orion-Tr, it has a built-in steel frame that’s engineered for easy mounting. It’s actually lighter, tipping the scales at only 3.13 pounds. This makes it suitable for racing and other applications where every ounce matters.

Renogy DCC50S

This charger can handle almost every type of battery. In addition to lithium, it can charge AGM, GEL, and flooded batteries. With a maximum output of 50 amps, it’s more powerful than most compact chargers. Not only that, it sports a full array of safety features. It protects your batteries from over-voltage, overheating, over-current, reverse current, and other concerns. Not only that, but the DCC50S has a voltage sensitive relay that will work well with most alternators.

The DCC50S supports both solar and alternator DC power. For solar, the maximum input is 660 watts at 25 volts. This means you can run 12-volt solar panels in pairs for 24-volt charging. You won’t often make use of this feature in a car, but it’s a huge benefit for off-grid charging.



Last on our list is the REDARC BCDC1225D. This charger is ultralight, at only 1.54 pounds. It’s also ultra-slim, measuring 10.24 inches wide, 4.92 inches deep, and less than 1.9 inches thick. This makes it suitable for installing in unusual locations, such as the inside of a vehicle door or hatchback. Because it’s so slim, you can put it just about anywhere.

The BCDC1225D falls right in the middle of our last two offerings. It provides up to 25 amps of juice, although it can provide less as needed. In fact, this variable voltage is the REDARC charger’s main attraction. It’s designed to run off your primary battery, not your alternator. When your secondary battery, it delivers charge as needed. However, when your secondary battery is full, it goes into “float” mode. In this mode, the BCDC1225D stores excess power, and only delivers a slow, 0.5-amp trickle charge. When more power is needed, this stored power can immediately be delivered without draining your primary battery. This in turn gives your alternator plenty of time to keep up with the increased overall power usage.


Like the last two chargers we looked at, the BCDC1225D can also operate off a solar panel. It has a built-in regulator, and will automatically deliver the correct charge. As a result, you can connect it directly to your solar panels, without the need for a regulator. All of this is covered by REDARC’s two-year manufacturer’s warranty. In the event of early failure, you get a replacement or a full refund.

Final Verdict

As you can see, each of these DC to DC battery chargers has its own strengths and weaknesses. So, which one is right for you? It depends on what you need. We started out by reviewing the Victron Energy Orion-Tr Smart DC-DC Charger. This charger is compatible with lithium and lead-acid batteries, and supports a wide range of input voltages. It’s easy to install, easy to use, and easy to control with the Bluetooth app. The 30-amp current might not be enough for some applications. But for your average automotive backup battery, it’s going to provide more than enough power.

The Renogy DCC50S 12V 50A DC Board Battery Charger is a little more powerful, providing 50 amps of power. It’s also a bit beefier, which could make it harder to fit in a smaller engine compartment. That said, it offers a few distinct benefits. For one thing, it works with state of the art AGM batteries. It also supports up to a 25-volt input, so it’s safe to use on a 24-volt solar system. This is a significant benefit for off-grid use, where power use spikes and zeroes out as people come and go.

The REDARC BCDC1225D is a mid-powered charger that delivers 25 amps. However, it’s also the smartest of the bunch. Its ability to deliver a trickle charge and store extra power makes it useful for systems that are used irregularly. Regardless of when your backup battery is needed, it will be fully charged and ready to go.

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