DCDC Battery Charger 101: Van Conversion Explained

A brief explanation of a dcdc battery charger. What is a dc to dc battery charger, how are they used, and what do you need to know about installing a dcdc charger in a van conversion?
DCDC Battery Charger 101: Van Conversion Explained

A DCDC battery charger allows you to charge your leisure battery in your campervan with your van’s engine.

This system allows you to be off-grid when it comes to generating power and harnesses the power of your engine to charge your leisure batteries for free whilst driving!

This blog will briefly explain how a dcdc charger works and what to look for when buying a dcdc charger for your campervan.

How does a DCDC charger work?

DCDC chargers, or alternator chargers, connect to your van’s starter battery and charge your campervan leisure battery.

In a standard van, when you turn the engine on, an alternator in your van spins, generating power and charges your van’s starter battery.

A DCDC charger harnesses this power, piggybacks into this, and sends power from your van’s starter battery to your leisure battery when the vehicle is turned on.

This way, your alternator is essentially charging your van’s starter battery and your leisure battery!

You cannot use a dcdc charger when the van engine is off.

If you try to do this, you will drain your van start battery of all its power, and you won’t be able to start the van.

DCDC chargers with lithium and lead acid batteries

With campervan batteries, there are two main types of batteries: AGM Lead Acid and Lithium.

DCDC chargers have different settings, allowing you to charge different types of batteries. If you have a lithium leisure battery, you need a DCDC charger which can charge lithium batteries.

Because the battery chemistry is different, the charging parameters are different.

This is why there are different charging profiles, depending on the battery you are charging.

You also CANNOT put a thick wire between the starter battery and your leisure battery under any circumstance. This incorrectly joins your van’s starter battery and your leisure battery together, unsafely.

What does the number on the DCDC charger mean?

DCDC chargers are measured in Amps (A).

The higher the number, the more power this DCDC charger can provide to charge your leisure batteries.

Most of the time, a 20-40A DCDC charger will be sufficient. We installed a REDARC 50A DCDC charger in our campervan since we were going to need a lot of power.

The DCDC chargers have a lot of wiring to connect up, which we showcase in our electric schematic PDF, where we go over a lot more details of campervan electrics, including the dcdc charger.

Important information about DCDC chargers

Two important points to make about DCDC chargers.

First, most of them have an ‘ignition live’, which means there’s a smaller wire which detects whether your van’s engine is on. If it is, then it allows the DCDC charger to work. If it isn’t, then it stops it from working. If you don’t connect this wire, your DCDC charger might not work or might always be on, in which case it will drain your starter battery’s power.

Second, is the size of your van’s alternator. Most alternators have a maximum rating (in vans, this is usually 110A). On idle, vans use around 60A, so that means you only have 50A ‘spare’ to use for your DCDC charger before you overload your van’s alternator.

You can upgrade your van’s alternator to allow for larger DCDC chargers to be fitted to your van.

More information on DCDC chargers

This blog just scratches the surface of DCDC chargers.

We have a FREE Electrics 101 PDF for you to download, which explains the basics of a campervan electrical system, including DCDC chargers.

We also have an extensive Electrical Wiring Schematic, which explains every single product in a campervan electrical system, how they all connect together, how to know what sizes and types of products to pick, and some safety tips about campervan electrics.

And if you’d like to see us installing our DCDC charger and our entire electrical installation, we have an entire playlist on youtube dedicated to that.

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November 25, 2023

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