Is a Secondary Battery Necessary?

Is a Secondary Battery Necessary?

If you have been driving for a few years, you’ve likely experienced a dead battery once or twice now. Vehicles didn’t always come equipped with automatic head lights. (I know what a shocker. 😱) My first car had manual lights, meaning they had to be turned off.  Who knew leaving your head lights on for even a short period of time, could drain your vehicles battery so quickly? (Smh, should have known.) That right there can ruin anyone’s day, am I right?  Luckily, today’s rigs are built to accommodate all our accessories we use while on our adventures. Whether those accessories include running a winch, fridge, lights, air compressors, and other battery powered devices, having a secondary battery can seriously be a life saver. Our vehicles electrical system can only handle so much when it comes to all the different upgrades and modifications we use on our vehicle. Let’s face it, we rely a lot on our battery. Not only to start our engine every time we’re itching to get out on the trails, but to also keep our fridge cold, keep our lights on, and so much more. The last thing we want to happen when we’re exploring off the grid, is a dead battery. 

How do you avoid a dead battery? When your vehicle is running, the alternator job is to keeps the battery charged. But what about If you’re parked at your campsite, running your fridge and camp lights? Your battery is not going to last long. Using your vehicles battery while the engine is off is a quick way to kill your battery. Doing this could leave you off the grid longer than you had planned. Great news! There is a way to prevent this – a secondary battery. This upgrade is honestly one of the best ones we have ever done! This allows you to power those accessories and will also make sure your starter battery is topped off when it's time to go home.  

Ok, but how does it work? Having a secondary battery is exactly what it sounds like, “having a backup battery”. In a dual battery system, there is a primary battery and a secondary battery. The primary battery sole purpose is to start the vehicle. The secondary battery is dedicated to powering all your accessories when the engine is off. Fun fact about the secondary battery - if need be, the secondary battery can be used to jump start the primary battery. If you have a secondary battery, you will (almost) never have to worry about being stranded in the middle of nowhere without power. 

Now here’s the how part: These two batteries are wired parallel from each other, (positive to positive and negative to negative) through a relay. The relay than is wired to an ignition source (power) and that source then senses voltage to link the two batteries together when the engine is running. But when the engine is turned off, it isolates them so that the primary battery will not become drained while your secondary battery powers all the accessories that are running. (Now that’s some science, kids.)

Where does a Secondary Battery mount? In most popular vehicles such as Toyota, (4Runner, Tacoma) and Jeep, design kits specifically for this type of upgrade, and the placement is pretty simple, although it can vary from vehicle to vehicle. The 4Runner and Tacoma Secondary battery location is located on the passenger side of your engine bay, and typically are pretty easy to mount up. Most secondary battery’s require a Battery Box, to help keep the battery stable and in place when off-roading. There are many boxes to choose from, but you’ll want to go with a stainless steel or aluminum battery box, so it doesn’t rust when you’re out in unpredictable weather. That’s why we created our Stainless-Steel Secondary Battery Box! We know what it’s like to run out of power and space, which is why we also added mounting points for the Red Arc Charging Relay (blog coming soon).

 So, do you need a secondary battery? Only you can answer that question, all we can do is help you make an informed decision. If you’re looking for more information on secondary batteries or battery boxes, check out our sister blog. Till next time Rago Cool Kids.  


2016- 2021 3rd Gen Toyota Tacoma - Secondary Battery Box $215.95

2010-2021 5th Gen Toyota 4Runner - Secondary Battery Box $ 224.95

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