A good 4WD 12V electrical setup would usually include two batteries. The first one would be the main car battery for starting your ride while the second one is a service battery to help power essential appliances you have inside. This auxiliary battery ideally should be a deep cycle battery that has an 80% DoD for a longer run time. Preferably, a lithium deep cycle battery like a LiFePO4 would do an even better job if you're willing to invest in a quality battery. While a lot of 4WD beginners already know about this dual battery system, some still have yet to learn the other requirements and procedures necessary to install an entire 4WD 12V electrical setup.
Everything about wiring a 4WD 12V electrical setup can be complex so it's better to ask for help from a professional if you don't have prior experience. If you have been a seasoned 4WD adventurer for some time though, you should have no problem installing the entire system on your own.
What Do You Need For a 4WD 12V Electrical Setup?
You have your two batteries, what's next? Here are some other essentials required to smoothly fit a 4WD 12V electrical setup for your upcoming adventures.
Mounting Tray: Whether you're using an AGM battery or lithium battery as your auxiliary battery, mounting them securely is a must. Get a durable battery mount with straps or customise your own if you have limited space or a non-standard-sized battery. Some vehicles provide a space for battery mounting though, such as Toyota Landcruisers.
Battery Monitor: Tracking your batteries while in use is a great way to ensure that they are running smoothly. The easiest way to do this is through a remote battery monitor or coulometer. This device will easily indicate your battery's State of Charge (SOC), voltage, and power draw. You can also opt for more complex solutions if you want inputs from all devices involved in your 4WD 12V electrical setups such as inverters and chargers. Bluetooth technology is gradually being incorporated into lithium battery systems too, allowing a more convenient way of monitoring your batteries.
Battery Charger: You have several options for recharging your batteries. The easiest one is through your vehicle's alternator, which also keeps your secondary battery charged while you are on the go. It's either you use a Voltage Sensitive Relay (VSR) if your vehicle has a fixed alternator or a DC-to-DC charger for rides with a smart alternator. This is because your alternator will drop voltage once your battery bank is full and a VSR may not be able to detect this, causing it to stop charging your auxiliary battery as well. Using solar panels? That's a great way too, as long as you use a solar charge controller to keep your battery from overcharging.
Inverter: Want to bring your favourite coffee maker or maybe run a heater for cold nights? You'll need an inverter for that. This device is necessary for powering larger 240V appliances, so it's important that you select a quality one with all the necessary electronic protections in place.
Lights: Get a good lighting system for your 4WD 12V electrical setup. You want to be able to locate everything even in low light settings so a good camp light bar or adhesive light strips would be a great finishing touch.
How To Install Batteries In a 4WD 12V Electrical Setup?
Since a lot of 4WD owners opt for a 4WD 12V electrical setup with VSR, let's focus on the installation basics of systems that use this charging device. The first step you have to do is to mount your auxiliary battery and ensure you have enough wire for the necessary connections. Disconnect your starter battery, then set up your VSR. As much as possible, place it near the main battery and away from any sources of heat. Cut the cables to length and attach the lugs at the end, then put the heat shrink over the lug and apply heat to create a water-resistant seal.
Use the black wire on your VSR to earth the relay and connect your main battery to it. Earth your auxiliary battery, then attach the VSR to the mounting plate. After this, attach the negative leads to the car battery and then to the second battery. Once you're done with the entire setup, it's time to test if everything is working well through a multimeter.
How To Distribute Power From Your 4WD 12V Electrical Setup?
Just like charging, there are several ways to transfer power from your 4WD 12V electrical setup to your accessories. You can use a battery box as long as it's properly wired up with all the fuses and circuit breakers required to protect your appliances from electrical damage. Another option would be to use a 12V control box. This method is usually used if you have multiple batteries that cannot be fitted in one box and it looks just like the electrical boxes usually found at the sides of your home. Lastly, you can connect your devices directly to your battery power pack too, although this is the least recommended solution out of all three.
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