What is a DC to DC charger and do I need one?

By Jessica Palmer 4 Min Read
REDARC classic under bonnet DC to DC battery charger © REDARC

If you’ve got a recently installed dual battery, or are looking into setting one up, you may be wondering what a DC to DC charger is and trying to work out whether you really need one. So in this article, I’m going to explain the basics of what they are, what they do, and discuss whether you need one.

But first, let’s quickly talk about the difference between AC and DC current.

AC vs DC and the importance of a dual battery 

Not just a band name, AC and DC refers to two different types of electrical current. AC (alternating current) is the type of current used in most houses and the majority of your household appliances will run on this type of power. 


DC (direct current) is used in most vehicles and small appliances found in boats and caravans use this power, including your portable camping fridge. To power these important appliances, you’ll need a second battery or dual battery set-up. If you were to rely on your car’s main battery to power all these extras, you will no doubt end up with a flat battery and won’t be able to start your 4WD.

Having a second battery leaves your vehicle’s main battery to focus on its job of powering your 4WD and your second battery is used to power all your camping gear such as your fridge and lights.

Projecta DC to DC battery charger © Projecta

Yes okay … but what is a DC to DC charger?

A DC to DC charger is a clever little device that runs off 12 volts. It takes power from your vehicle’s alternator while you are driving and creates an output voltage and current that will charge and maintain your ever-important second battery. You know, the battery that runs your fridge and charges your devices while you’re camping and 4WDing. 

How they do this is a story for another day.

How does it work with solar power?

Charging from your alternator with a DC to DC charger and using solar panels are the two most common ways to manage your power needs when camping and going off-grid. A good quality DC to DC charger will have a built-in solar regulator but if it doesn’t, you can purchase a solar regulator as a separate unit.

dc to dc charger
DC to DC charger for both solar and alternator power sources © Projecta

What about wiring the second battery the old-fashioned way?

If you have an older vehicle with an old-fashioned dual battery parallel wiring set-up, a DC to DC will improve your second battery charge and maintenance. Why? Alternators were never designed to be used as designated battery chargers and the DC to DC charger is clever enough to optimise the charging.

Newer vehicles with low-output alternators benefit from this charging optimisation as well. Basically, a DC to DC charger will charge your second battery more efficiently than traditional parallel wiring regardless of your vehicle type.

Do I need one?

All charging options come with pros and cons and as a result, it’s best not to rely on just one. So while you don’t technically need one, it’s very handy to have and combined with solar, is a viable way to manage your power needs when you’re on the road or off-grid camping.


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