Dual Battery Systems FAQs

1. What is a dual battery system, and why do I need one for my 4WD?
• A dual battery system allows you to run accessories like fridges, lights, and other electrical loads without draining your vehicle's starting battery. It's essential for off-road adventures or camping trips where you need reliable power for extended periods.
2. How does a dual battery system work?
• It works by adding an auxiliary battery into the vehicle. The alternator charges both original starting and auxiliary batteries, but the isolator separates the auxiliary battery when the engine is not running, ensuring the starting battery is preserved while the auxiliary battery powers your accessories.
3. What type of batteries are suitable for a dual battery system?
• Deep cycle batteries (flooded, AGM, or Lithium) are ideal for dual battery systems because they are designed to provide consistent power over long periods and handle repeated discharging and recharging.
4. Can I install a dual battery system myself?
• While possible, it's recommended to have a professional install your dual battery system, to ensure correct wiring and integration with your vehicle’s electrical system, especially when dealing with modern vehicles that have sensitive electronics.
5. How long will a dual battery system power my fridge?
• This depends on the size and type of the battery, the fridge's power consumption, and how often the fridge runs. A typical 100Ah deep cycle battery can run a 12V fridge for 24–48 hours without charging, but there are many factors like ambient temperature, fridge efficiency, other electrical loads and initial battery state of charge that impact this time frame.
6. What is a battery isolator, and why is it important?
• A battery isolator prevents your starting battery from being drained by accessories connected to the auxiliary battery. It ensures the starting battery always has enough charge to start the vehicle. These can take a few different forms, are simpler and cheaper than DC-DCs and, depending on the set-up, can still be an effective solution.  
7. Do I need a DC-DC charger for my dual battery system?
• A DC-DC charger is a fancier isolator with more abilities, and highly recommended, especially in modern vehicles with increased sophistication in alternator management. It ensures that the auxiliary battery is charged efficiently, even when the alternator output is low, and it also provides proper charging profiles for AGM, Gel, and Lithium batteries.
8. Can I use a solar panel with my dual battery system?
• Yes, solar panels are a great way to add charge to your auxiliary battery when your vehicle is stationary or on the move. A solar regulator or a DC-DC charger with a solar input is needed to properly manage the charging process. The ability of solar to top up the system is dependent on a range of factors like size of panel, panel orientation, cloud cover etc.
9. How do I monitor my dual battery system?
• Battery monitoring systems can be as simple as a voltage gauge read-out, or as flash as smartphone app, providing real-time information on voltage, current, and charge levels for both batteries. These systems help you track the health of your batteries and prevent over-discharge.
10. How do I maintain my dual battery system?
• Regularly check the battery terminals and cables for corrosion and tightness, ensure proper charging through alternator or solar, and occasionally test the battery’s health. If using AGM or flooded batteries, check for any signs of swelling or damage. Despite the best efforts of vehicle or solar charging, the most complete battery charging is going to be from a decent 240volt battery charger. Worth hooking up overnight occasionally, especially if the vehicle is not in regular use.
11. Will a dual battery system affect my vehicle’s warranty?
• Generally, if installed correctly, a dual battery system should not void related aspects of your vehicle’s warranty. However, for peace of mind, it’s a question you could put to your vehicle’s manufacturer or dealer.
12. How much does it cost to install a dual battery system?
• The cost varies depending on the components used (e.g., battery type, charger, monitor) and labour. A basic system can start at around $500, while more advanced setups with lithium batteries and solar integration can run into thousands of dollars.
13. Can I run more than one auxiliary battery in my ‘dual’ battery system?
• Usually, yes, although physical space, cost and weight are big factors to consider. As many of the ‘gadgets’ that are more so becoming part of peoples camping set-ups, increases electrical load, more power via additional batteries may be required. However, it's crucial to ensure the system is properly configured to handle multiple batteries.
14. What’s the go with invertors?
• Invertors step up 12volt DC electrical current from batteries, to 240volt AC, like your house. This allows a wider range of electrical appliances to be run while ‘on the road’ but is a power hungry and inefficient process. Bigger is not better when talking about invertor capacity, however invertor output capacity needs to be greater than the devices demand (e.g. a 1200W microwave would need a 1500W invertor). It can be done, but rapidly increases cost and complexity of a dual battery system when needing to run big invertors. Tricky to do within a 4WD – best left to be installed in a caravan!.

For more information give the experts a call on 03 9762 1200 and we can help you out.