If you love off-roading or hitting the trails, you’ve probably run into the same issue: you need extra power for fridges, lights, water pumps, and accessories — but space is always limited. That’s where an under-bonnet battery kit becomes a game-changer.
By housing your second battery neatly under the bonnet, you can build a clean, reliable dual battery system without sacrificing tray or canopy space — perfect for touring, work setups, and off-grid adventures.
Before installing an under-bonnet battery kit, there are a few key things to consider to ensure your setup is safe, efficient, and built to last.
1. Check Engine Bay Space for an Under-Bonnet Battery
Not every vehicle has enough room to fit a second battery under the bonnet, so this is the first thing to check.
When measuring your engine bay, make sure you:
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Measure carefully and confirm battery dimensions
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Maintain access to fuses, hoses, and service points
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Allow for regular maintenance without removing the battery
While some universal kits may fit, many vehicles benefit from a custom under-bonnet battery compartment. A vehicle-specific solution ensures correct fitment, safer mounting, and easier servicing long-term.
2. Choosing the Right Battery for Under-Bonnet Use
Battery choice has a huge impact on performance, weight, and lifespan — especially in a hot engine bay.
Popular battery options include:
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Lead-acid batteries: Traditional and very cost-effective, reliable for basic starting and deep-cycle use but heavier, require ventilation, and less tolerant of deep discharge compared to newer technologies.
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AGM batteries: More budget-friendly, heat-tolerant, and well-suited to under-bonnet installations
When choosing a battery, ensure it:
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Fits the available space
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Is rated for engine bay temperatures
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Matches your power requirements
A high-quality battery makes all the difference when running a dual battery system in a 4WD.
3. Wiring & Safety for Dual Battery Systems
Correct wiring is critical for safety and performance — especially in under-bonnet setups.
Best practices include:
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Using correctly sized cables to prevent voltage drop
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Installing fuses close to the positive terminal
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Running a DC-DC charger or battery isolator to safely charge while driving
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Labeling wiring for future troubleshooting
Cutting corners on wiring can cause charging issues, heat buildup, or even fire risk — doing it right from the start is essential.
4. Managing Heat in the Engine Bay
Heat is the biggest enemy of any under-bonnet battery installation. Excess heat shortens battery life and can impact reliability.
To protect your battery:
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Use heat shielding or thermal wraps
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Ensure airflow around the battery compartment
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Avoid tightly cramming batteries into confined areas
A well-designed under-bonnet battery kit balances protection, airflow, and durability.
5. Why Custom Under-Bonnet Battery Kits Are Worth It
While off-the-shelf solutions can work, custom under-bonnet battery kits often provide better long-term reliability and fitment.
With an Elevate Automotive under-bonnet battery kit, you get:
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Vehicle-specific fitment
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Secure mounting for harsh Australian conditions
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Clean cable routing and protection
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A factory-style finish
Our kits are designed to support reliable 4WD dual battery systems built for touring, work, and remote travel.
Final Thoughts: Is an Under-Bonnet Battery Kit Worth It?
An under-bonnet battery kit is one of the smartest upgrades you can make if you want reliable power without sacrificing tray or canopy space. With the right planning, battery choice, wiring, and heat management, it becomes a dependable part of your 4WD electrical setup.
At Elevate Automotive, we don’t just supply under-bonnet battery kits — we professionally install them too. Every install is carefully planned, wired, tested, and finished to ensure your system performs when it matters most.
👉 Learn more about our 4WD installation services: Elevate Automotive Installations
