Our Guide To 4WD Dual Battery Kits & Systems

Our Guide To 4WD Dual Battery Kits & Systems

Thinking about powering appliances from your 4WD? You’re going to need an auxiliary battery. In other words, another battery in addition to your starter battery.

There is a wide range of 4WD dual battery kits available to suit different vehicle types and installation types.

Read on to find out how to choose the right 4WD dual battery kit for you.


Option 1. Mount A Battery Isolator Or Voltage Sensitive Relay (VSR) Under The Bonnet

The oldest and most basic style is to have just a battery isolator or voltage sensitive relay (VSR) mounted under the bonnet. This is connected to the start battery and the auxiliary battery. 

This is an unregulated charging method used for vehicles with traditional alternators (not smart) and is designed for charging lead acid batteries.

We recommend: Enerdrive Dual Battery Kit.

The Enerdrive Dual Battery Kit is designed for safe charging and separation of the starting and auxiliary batteries in all 12V marine, 4WD, caravan and solar applications. 

This means, when the engine is started, your starting and auxiliary batteries are separated and only the starting battery is charged. 

When the charge voltage reaches 13.3 volts, the Voltage Sensitive Relay engages so both starting and auxiliary batteries can be charged. You will know when this occurs because a red light will illuminate. 

When the engine is stopped and the battery voltage falls below 12.8 volts, the VSR disengages, again separating the start and auxiliary batteries. The auxiliary battery continues to power any accessories without draining the starting battery.

The great thing about the Enerdrive VSR is that it also has Dual Sensing which senses the charge of both batteries. So, if either battery is receiving a charge, e.g. a battery charger is connected to the auxiliary battery, the VSR will engage and charge both batteries.


Option 2. A Dedicated DC To DC Charger Connected Between Start Battery And Auxiliary Battery

This is the preferred option and there are many of these products available. 

Most quality DC to DC chargers have the option to charge a lithium battery and are suitable for connection to a vehicle that has a smart alternator.

We recommend: Enerdrive 40A DC to DC Battery Charger.

The Enerdrive ePOWER DC to DC battery charger is a fully automatic multistage, multi input battery charger which can either charge from an alternator linked to a battery, or via solar power with the in-built MPPT Solar Controller. 

This kit has been designed for in-vehicle installation.

You can choose the Enerdrive 40A DC to DC battery charger with installation kit or with the midi fuse installation kit.

Looking for a more advanced 4WD dual battery kit? Enerdrive has it covered with the 4WD canopy systems

These compact power solutions are designed to operate all of the electrical equipment that is located in 4WD canopies, from a simple fridge or lights setup to a full-on power station. 



All systems are pre-wired by Enerdrive where possible, so all you need to do is sort out the cabling for load outputs, battery connection, and vehicle/solar/tank inputs. 

No matter which you choose, the system comes built into a compact box which is designed to mount on either the front or rear bulkheads of the canopy. 

To connect your starter battery to the canopy system in your vehicle you will need the right cable kit - this 16mm Cable Kit by Enerdrive is made for the job. 

Option 3. Under Bonnet Mounted Dual Battery System

The latest and greatest dual battery system is the under-bonnet mounted Invicta Hybrid Lithium Starter range. This new technology allows you to mount a lithium battery as your second battery under bonnet. When combined with a BMPRO DC DC ProBoost (which can also be mounted under bonnet) you can charge your auxiliary battery via DCDC and solar. For 4x4's this is perfect to free up room in the cabin for fridges, drawers and other gear.

One of the standout features of the Hybrid models is the ability to act as a cranking battery. The battery reserves 20% of it's power for this emergency feature. Simply hit the button on the top of the battery or control it via the bluetooth app. The MAX version can even power a 4x4 winch. Check out this winching video to see a battery only winching using a MAX Invicta Hybrid Lithium Under Bonnet Battery.


In sizes from 60Ah to 80Ah with CCA Range of 100 to 1400 there is an under-bonnet battery for every application.


Slimline Batteries

New to the market in 2023 is a range of lithium batteries specifically designed to be compact in size to fit in tight spaces in your 4WD while saving space. Slimline Lithium Batteries are perfect for those looking to maximise their available power storage capacity, as they offer more power in less space. 

If you're in the market for a reliable and efficient Slimline Lithium Battery, Enerdrive's B-TEC range is hard to beat. These batteries offer an impressive 60% more usable power compared to its lead acid counterpart, while also boasting the benefits of being almost 50% lighter and 30% smaller. It's the perfect choice for camper trailers, 4WDs, caravans and boats. Its sturdy metal casing also makes it a top pick for canopy and 4WD applications. On offer in the range is:


In 2023, Invicta also released their thinnest lithium battery ever, the Invicta Super Slim, in response to the challenge of shrinking available space within vehicles. The compact 65mm wide frame, makes it perfect for installation behind the back of seats. Plus, the durable metal case provides protection against impacts and squeezes in tight spaces. There are currently two sizes available in the range:


Check out our full range of 4WD electrical accessories to find your best fit.


DISCLAIMER* Please note, this advice is general in nature and we strongly recommend consulting the product manual and where relevant, a professional installer.

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