Everything You Need to Know About Dual Battery Systems

It’s only natural that everyone wants to make their camping experience as smooth as possible. Usually, this is done with the help of carrying portable fridges, laptops, smartphones, cameras and portable ovens. No matter how good it sounds, if not camping in a powered campsite, charging all these electronics can be quite difficult. The ideal solution for those of you who can find themselves in a situation like this is to use a second battery with a dual battery system.

The purpose of dual battery systems is to isolate the second (auxiliary) battery from the starter vehicle battery to avoid complete drainage. Although in the past dual battery systems were considered basic isolators, nowadays, they have evolved into powerful DC systems.

vehicle dual battery systems

Charging Option Comparison

In the past, the first dual system consisted of a manual switch in order to isolate the batteries when the vehicle is turned off. Although considered a simple and effective thing, this proved to be impractical as a lot of people forget to isolate their batteries. That is the reason why today’s dual vehicle battery systems are more “complicated” but more powerful and effective.

Basic Isolators – Instead of using a manual switch, basic isolators are controlled by ignition and can isolate the batteries when the vehicle is not running. This option allows the driver to run the auxiliary battery flat, but according to mechanics, this can be quite tricky as the engine might not have enough power to start over when turned on after a while.

Smart Isolators – Thanks to this “problem”, manufacturers have managed to create smart isolators which are more expensive but more effective when compared to the basic ones. The purpose of smart isolators is to cut in and out at certain voltages which allows the flat auxiliary battery to remain disconnected until the starter battery is completely charged.

DC to DC Chargers – The newer types of vehicles have smart alternators that emit enough power to charge the starter battery and to disconnect it when fully charged. Unlike traditional isolators, the DC systems have a battery charger that plugs into 4WDs wiring but can also be recognised by smart alternators. This setup can create two separate electrical systems so that the battery can never go flat.

Battery Types

Batteries have evolved a lot over the years, so now there are lots of them available on the market. Lightweight batteries, batteries with more energy capacity and deep cycle batteries are just some of the many from which you can choose. They all differ by features and energy power, but the one thing they all have in common is that they are rated in Amp hours. This is the number of amps which can be discharged in 1 hour. The more Amp hours a battery has, the longer it’ll last.

Flooded Lead Acid Batteries

These are the cheapest and oldest types of batteries, which are also considered the ideal starter battery. It is filled with lead plates and liquid acid which can emit dangerous fumes, thus must be mounted upright and away from passengers.

AGM Batteries

The AGM (absorbent glass mat) batteries are designed of fibreglass mats that are attached together with the help of liquid acid. They have slow discharge rate and can run perfectly for a few weeks without recharging. These batteries are leak-proof which means that they can be mounted everywhere and near passengers as well.

Gel Cell Batteries

These batteries are considered better than the AGM ones. They consist of gel acid which is better than liquid acid, they’re maintenance-free and leak-proof, and can’t handle the needed intense load for engine starting.


Lithium batteries are designed of lightweight chemical instead of gel or fibreglass matting. They are the latest invention in battery technology that is predicted to dominate the industry and can be put to use when it come to smartphones and laptops too.