Dual Batteries

In days gone by the Four Wheel Drive was primarily used by tradies and farmers because of it’s ruggedness and ability to carry passengers as well as tools and equipment. However, in recent years the product and market has changed, and the dual cab has become a vehicle style of choice for recreation and four wheeling, drivers with towing requirements. With an endless list of potential accessories and modifications available, it can be a daunting process when looking to pimp out your new 4×4, and there are some mods that should have a higher priority placed on them than others. If you want more freedom away from the city limits, one of the first areas which you should look to improve is the vehicle’s electrical setup.
Understanding Alternators The alternator is the power supply used by the vehicle to recover its start battery from the engine starting process and provide power to its electrical consumers once running – eg. stereo, air conditioning, engine cooling fan etc. There are two common types of alternators, the traditional fixed-voltage alternator and the now most common smart alternator which is fitted to most vehicles manufactured after 2011. The fixed voltage alternator produces sufficient voltage to successfully charge a secondary battery, whereas smart alternator technology adjusts its output voltage based on the vehicle operating conditions and electrical load. The vehicles engine computer sends a signal to the smart alternator telling it to only produce enough charge to cover the calculated load, this is to reduce the electrical load, and in turn, the mechanical load on the engine contributing to better fuel economy. This renders it unsuccessful at charging a secondary battery to a usable level when the secondary battery is paired in to the start battery in the traditional way. Widespread implementation of smart alternators means that the once trusty process of parallel charging from the start battery to the secondary battery is not effective in vehicles equipped with this technology. This is because, for all the things a computer in a smart alternator vehicle knows, it does not consider the secondary battery’s state of charge, type or location in the vehicle in its calculations.
Battery Blues Most vehicles are built with just one starting battery, so installing a second battery for auxiliary purposes is required to increase capacity and allow loads to be run when the vehicle is off. This can be a tricky process and really depends on your vehicle. In years gone by an under the bonnet install was a common occurrence, but not anymore, due to a lack of space and higher levels of heat being generated from the engine. The fact is that the best location for the install of secondary battery depends on your vehicle. Some utes lend themselves to a secondary battery being installed behind the rear passenger seat or under the tray, others inside the tub or on the tray.
Charging Options:
DC to DC Battery Chargers A DC-DC Charger which can best be described as a battery charger you have at your home, but only that it plugs into the vehicles wiring system instead of a wall. A DC-DC charger protects the start battery like an isolator does, but when charging it actually boosts the charge to the auxiliary battery. The DC-DC charger is wired into the vehicles ignition system and the power that the DC-DC charger requires to run is calculated into the engine computers electrical calculations (like adding spotlights to the vehicle). The DC-DC charger is operational and charging the secondary battery as soon as the vehicle’s ignition is switched on, or if there is a solar input option to provide power to the DC-DC charger whilst the vehicle is switched off. It is ideal to locate the DC-DC charger as close to the secondary battery as possible providing optimum chance of charging. It is also ideal to locate the secondary battery and DC-DC charger close to the accessories you wish to run off the secondary battery saving you installation costs of cabling the items from the engine bay.
Smart Battery Isolators The trusty Smart Battery Isolator (SBI) is the most simple and time-tested approach to using your vehicle’s alternator to charge the second battery, only whilst the vehicle is running. Its job is to also protect the start battery from going flat by isolating it from the secondary battery when the engine is turned off. A battery isolator will recognise when the vehicle engine is running, and charge is going to the starting battery via the vehicle’s alternator. It will do this by sensing battery voltage, and when the start battery reaches 13.2 volts (on a 12-volt system), it will connect and start charging the secondary battery. An SBI is best suited for vehicles that have a fixed voltage alternator and not smart alternator technology. Vehicles with smart alternator technology are unable to detect the secondary battery so don’t know to provide charge for the secondary battery. Although it is still possible to fit a SBI to a vehicle with smart alternator technology the secondary battery will not receive full charge and therefore shorten the life of the secondary battery as well as running the risk of not having enough charge in the secondary battery to run items, like a fridge, for the length of time that the vehicles engine is switched off.

There are many different types of dual battery chargers on the market and there are several factors which will dictate which one is best for your dual cab ute. This includes the type of battery you have, the type of alternator your vehicle has, the location of the install and power you require. Features do also vary, such as the ability to accept additional power sources such as solar. The best solution for your vehicle ultimately depends on a range of factors and variables relating to your needs

Battery Trays