Can You Run Two Batteries Off Of One Alternator?

A car or vehicle with plenty of electronic components to support or a massive electrical grid can be very demanding for its battery and its alternator. This is usually the case for RVs and camper vans. It can also be why some people out there who would like to have a dual battery system on their vehicles.

With this, it will allow them to have a separate battery that will solely support the electrical grid of the car, while the automotive battery will only be responsible for the ignition of the engine. However, having a dual battery system can be a bit difficult to do.

Can you run two batteries with one alternator? YES! A vehicle’s alternator is very much cable of charging two batteries, but running a dual battery system through it can a bit complicated.

Adding a second battery to be charged by the alternator requires proper reconnection between the alternator and the two batteries. It can be too much for the alternator with wrong connections, or it can be dangerous for the cells.

Running a dual battery system will also require you to use a battery isolator to make sure that everything will run smoothly when it comes to the charging operation of the two batteries hooked up with the alternator.

To make this possible, you should have the know-how about how a car’s charging system work.

Finding you here reading my article gives me an idea that you are probably looking to hook up a dual battery system on your vehicle. I might be wrong, but the fact that you are here, you are trying to figure out if an alternator can charge two batteries.

Well, you got your answer earlier, but I encourage you to stay for a while because this guide has plenty of information about hooking up two batteries with an alternator.

A Complete Overview on a Dual Battery System

Adding a few electronic components on your truck, such as a massive audio system, portable fridge, winch, and other devices, will significantly increase its power requirements.

Due to this, a friend of yours has probably suggested to hook up an additional battery and run a dual cell system on your truck. This will provide you plenty of power to keep up with your truck’s power requirements without affecting cranking power and its primary system.

How a Dual Battery System Works

The way a dual battery system work is the alternator or the vehicle’s charging system is connected to a device called isolator. This battery isolator is then connected with the stack car battery as well as the additional cell.

When the engine is not running, or the vehicle is parked, the isolator automatically prevents the stacked battery from being drained. However, the isolator may also have a switch that can manually override this setting.

On the other hand, when the engine is running, the battery isolator opens up to allow the alternator to provide electricity to both batteries, charging both of them at the same time.

A system like this often uses a starter battery and deep-cycle cell, allowing one to support the basic needs of the vehicle and having the other one to support the electrical components.

Having a dual battery system is an excellent thing if you can afford it, and you really need it. It is always a good thing if you need one for various commercial and heavy-duty applications.

However, hooking up a dual cell system on a vehicle can be impractical for some people. Due to its cost, some people consider it to be a waste of money.

Think about it; a typical setup of a dual cell system can easily cost $250 to $450. This includes the cost of the additional battery, isolator, cables for the connections, and other materials needed for the entire system.

It also requires the appropriate expertise to get it set up, and if you don’t know how to do it, you will have to pay professional to do it for you to make sure everything is properly done.

Benefits and Drawbacks of a Dual Battery System

Now that you know how a dual battery system actually works and understand the anatomy of the system. It is also imperative for you to learn about the benefits of having a system like this and understand the drawbacks it also has.

With this, you will have the opportunity to think things through and see whether you need one.

The Advantages of Dual Battery System

Let us take a look at the advantages a dual battery system has to offer. This will give you an idea of what you can get from having a system upgrade.

Check out the list of benefits below:

● Having a dual battery system ensures that your vehicle won’t have any issues with ignition. This boosts its performance, even in extremely cold temperatures.
● With a dedicated secondary battery, you will have plenty of power to support additional electronic devices and accessories. A system like this is also ideal for outdoor adventures such as camping, fishing, and more.
● Hooking up an additional battery will also extend your starter battery’s service life, allowing you to save money in the long run. Having a dedicated battery to support the power requirements of the electrical components of the vehicle will preserve the starter battery.
● Reduces the risk of being stranded with a dead starter battery because the starter battery is only dedicated to the ignition of the vehicle. With a second battery hooked up in your vehicle, you can also perform jump-starts if the starter cell dies on you.

The Disadvantages of Dual Battery System

After taking a closer look at the benefits that a dual battery system has to offer, you also have to learn about its drawbacks. The disadvantages of getting one setup.

Here’s a list of those things you have to think about:

● Upgrading to a dual battery system is very expensive, and if you are only doing it for the sake of luxury, it can be an impractical thing to do. Having a system like this will cost you around $250 to $400, which does not include the service fee if you have a professional do it for you.
● Setting up a system like this is also a complex process that requires appropriate expertise. It’s not just adding a second battery and use additional wires to connect it. It is actually easier said and done, and incorrectly setting it up will be very risky.
● A dual battery system will also have additional weight to the vehicle, making it heavier than usual. Having an additional battery will also require you to allocate a dedicated space for it to reduce the vehicle’s storage space.

Those are the benefits and drawbacks that you have to understand before deciding if you need to have an upgrade. It clearly shows that it offers a lot of great things, but taking a look at the drawbacks, they are also enough to think twice.

So, it will be up to you to decide.

Step By Step Guide on Setting Up a Dual Battery System

As I mentioned earlier, having a dual battery system on your car or truck can be very expensive due to the materials you have to buy. Setting it up is also too complicated and may require you to pay a professional to do it.

However, having the proper knowledge of how to do it will allow you to reduce your expenses. So, to help you save a bit of money if you decide that you need your system to be upgraded, here’s a guide to walk you through the entire process.

Step1: Procuring All the Materials Needed for the Upgrade

Before you can set up a dual battery system, the first thing you have to do is get everything you need. You first have to choose the secondary battery, which, preferably, has deep-cycle capabilities. You also have to procure a battery isolator that is a vital component of the setup.

It will also be imperative for you to gather other materials for additional wirings, especially if the placement of the secondary battery is far from the engine, and the appropriate tools that you will need. A battery tray will also come in handy for the secure installation of the secondary unit.

Step2: Planning the Layout and Picking a Spot for the Secondary Cell

Prior to going to work and carrying out the upgrade process. You first have to plan the entire layout and pick the best spot for the second battery to be installed.

The ideal location would be the engine compartment, but it will require a lot of work since you will need to make room for the second battery within it. You can also consider putting the second battery in the trunk, but it will need longer wiring.

Anyway, it will be up to you since you are the one to do it. Pick the most convenient spot, but make sure that it won’t get in your way or make the passengers uncomfortable.

Step3: Installing the Battery Tray and Mounting the Secondary Battery

Once the ideal spot is determined, the nest thing you have to do is to install the battery tray that will securely hold the additional battery in place. Drill holes for the screws to make sure that it sits perfectly on the spot you chose.

You also have to drill holes where the cables will fit if necessary. This is why it is recommended to pick the spot away from the gas tank and other vital car parts.

Step4: Preparation for Integrating the Isolator with the System

Now to get to the more detail-oriented parts of the process. You have to prepare the system for adding another component, which is the isolator.

To do this, disconnect the cables connected with the starter battery, start with the negative cable first to avoid shorting the system. You also have to make sure that the cable that connects the alternator with the battery is disconnected; it is the positive cable.

Step5: Introducing the Isolator to the Vehicle’s Charging System

The next thing you have to do is to integrate the isolator into the system. The battery isolator will usually have three terminals, use one of the side terminals to connect with the cable disconnected from the starter battery and alternator.

This will result in a threeway connection between the alternator, isolator, and starter battery. To do this, you will need to use a crimping tool.

Step6: Connecting the Alternator, Isolator and Secondary Battery

This is where you are going to connect with the alternator, isolator, and the additional battery. Use an additional wire to connect the alternator with the central isolator terminal.

After that, take another additional wire and connect it with the isolator’s third terminal, then connect its other end with the secondary battery’s positive terminal. Make sure that you are using a cable long enough to make a good connection between the two.

And then, do the same process you did with the other positive terminal connection and connect this cable to the vehicle’s electrical system.

Step7: Making the Connection Between the Two Batteries and System

Finally, you have to complete the entire circuit to make the smooth current flow within the system. To do this, take another long wire, connect one end with the negative terminal of the start battery, and then connect the other end with the second battery terminal.

After that, make sure that every connection point will have firm connectivity and securely placed. And then reconnect the negative terminal of the starter battery to a metal ground.