Car batteries have been a mandatory component almost since the invention of the first production car. Nowadays there are all kinds of car batteries with one of the most advanced and versatile ones being 4WD batteries. These may look like the same exact batteries used in regular sedans and hatchbacks, but they're not. 4WD batteries are made to work in dual battery setups which involve using an additional battery alongside the one supplied with your vehicle. This type of system works by providing power for vehicle electronics as well as for auxiliary items like kettles, laptops, or even a mini fridge.
Installing a Secondary Battery
Source: voltaic.net.au
What You Need
In order to have a dual battery setup all you need to do is add another battery into your engine bay. For this, you'll need a crimping tool, heat gun, pliers, a marker, a drill, drill bits, a volt gauge, a battery tray, and a VSR alongside the new 4WD battery pack.
Installation
1. The first thing you need to do is find a place for your secondary battery. Some people choose the boot for that but if your engine bay has enough room, put the battery there. When you've dedicated a place for your battery, place the tray in that exact spot.
2. Make sure that the spot you choose works together with the length of the cables. Once the tray is installed, disconnect the negative terminal of the main battery. After that, mount the VSR where you'll be able to access it easily. The VSR should also be away from any heat source and moving parts.
3. You should then take the red cable and measure from the centre of the VSR's mounting plate to the positive terminal of the main battery. Cut the cable to the correct length and do the same for the positive terminal of the auxiliary battery. With that done, fit the lugs on the ends of the cables.
4. Next comes the VSR earth wire. This requires you to attach the black wire to the VSR in order to earth it. After that connect the main battery to the VSR by connecting the red cable to where it usually says 'positive sense battery'. The same cable from the secondary 4WD battery needs to go to the terminal where it says 'positive second battery'.
5. Next comes the earthing of the secondary battery. For this, you'll need a solid earth such as a factory engine ground. The same black wire needs to be used like the one you did when earthing the main battery.
6. Once the secondary 4WD battery has been earthed, you need to attach the VSR to the mounting plate. Do this by using the two longer screws. Once that's done, continue by securing the negative terminals to the main battery first and then to the auxiliary one.
7. Finally before you close up shop, make sure to test the new battery. The voltage should go over 13.3 V and the relay should click once that happens. This is a sign that you've done the installation properly.
Benefits of Installing a Secondary Battery
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Convenient
An important reason why you'd add a secondary battery is that it can help run appliances and devices without the need to have your 4x4 running. This will help you lower your fuel consumption and it will also make it less stressful for the main battery.
Power
By having a battery dedicated only for the convenience-related features in your 4x4 you will be able to use them for a lot longer. But you will also be able to make the most out of them as with a dedicated battery there is nothing else draining it. You won't have to lower the heat of your stovetop just to save some power.
Versatility
With a dual battery setup, you get to use way more appliances and devices without worrying about their performance. You will be able to use way more power tools and systems such as air compressors, portable welders, inverters, drills and so on.
Types of Auxiliary Batteries
Source: motortrend.com
AGM
The most popular auxiliary batteries nowadays are AGM or absorbent glass mat batteries. This type of battery can be mounted in any place or orientation possible. They are also light and have a greater capacity than other types of 4WD batteries. The best 4WD battery for partial discharge is an AMG battery. Fully discharging AGM batteries is not a good idea though.
Lead-Acid
A good example of a 4WD deep cycle battery is a lead-acid battery. Lead acid batteries are the most affordable ones and they are preferred for full discharge and recharge. But keep in mind that they are not as low-maintenance as some other types of batteries.
Lithium
A lithium 4WD battery pack is the most durable option you can go for. But that's only the case in a partial use cycle. Lithium batteries are not as resistant to high temperatures and they are not usually able to fit under the bonnet.
