How to Connect 2 12V Batteries to Make 24V?

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Have you ever found yourself in need of a 24V power source but only had two 12V batteries at your disposal? Fear not, my friends! By connecting two 12V batteries in series, you can easily create a 24V power source for various applications, such as powering motors, alternators, and solar panels. I’ve got a ton of experience with this, so let’s dive in!

In this fun, informative, and easy-to-follow guide, we’ll cover everything you need to know about connecting two 12V batteries to create a 24V system. We’ll discuss the required tools, step-by-step instructions, and even some examples of dual-battery use. Stick around, and you’ll become a battery master in no time!

Tools Required

Before we begin, make sure you have these essential tools and equipment handy:

  1. Two 12V batteries (preferably deep cycle batteries)
  2. Jumper cables or battery wires
  3. Multimeter (to measure battery voltage)
  4. Protective gloves and eyewear
  5. Wire strippers and cutters

Using the proper tools is crucial for not only your safety but also the success of your battery setup. Remember, folks, safety first!

Connecting Batteries to Make a 24V System

Now that we’ve covered the basics of connecting batteries to make a 24V system, let’s dive into the step-by-step guide on how to connect two 12V batteries to make 24V, ensuring a seamless and efficient setup for your specific needs.

Step-by-Step Guide on How to Connect Two 12V Batteries to Make 24V

Now, let’s get down to business! Follow these simple steps to connect your batteries in series:

How to connect 2 12v batteries to make a 24v diagram?
  1. Safety first! Put on your protective gloves and eyewear.
  2. Inspect your batteries. Make sure they’re in good condition and have similar capacity ratings.
  3. Position the batteries. Place them side by side with the positive terminal of one battery near the negative terminal of the other.
  4. Connect the batteries. Use a jumper cable or battery wire to connect the positive terminal of the first battery to the negative terminal of the second battery. To connect 2 12V batteries for 24V output:
    • Get 2x 12V batteries and a jumper cable.
    • Place batteries side-by-side.
    • Connect positive (+) terminal of 1st battery to negative (-) terminal of 2nd battery using jumper cable.
    • Use remaining terminals for 24V output: 1st battery’s negative and 2nd battery’s positive.
  5. Test your setup. Use the multimeter to measure the voltage across the two unconnected terminals. If it reads 24V, congratulations! You’ve successfully connected your batteries in series.

A solid connection between your batteries is critical to prevent damage to the batteries and the electrical system. Always double-check your connections to avoid any sparks or short circuits.

Connecting Batteries to Make a 12V System

Having explored the concept of connecting batteries to make a 12V system, it’s time to dive into the step-by-step guide on how to keep the batteries isolated to create a 12V system, ensuring optimal performance and longevity for your unique application.

A. Step-by-Step Guide on How to Keep the Batteries Isolated to Create a 12V System

If you need a 12V system with higher capacity, you can connect the batteries in parallel:

12V system
  1. Safety first! Don your protective gear again.
  2. Inspect and position the batteries. Just as before, ensure they’re in good condition and have similar capacity ratings.
  3. Connect the positive terminals. Use a jumper cable or battery wire to connect the positive terminals of both batteries.
  4. Connect the negative terminals. Repeat the process for the negative terminals.

B. The Importance of Using a Battery Isolator or Selector Switch

Hey there, fellow battery enthusiast! You’re in for a treat, as I’m about to share some electrifying insights about battery isolators and selector switches. Trust me, these little gadgets can be real lifesavers when it comes to managing your dual-battery setup. So, buckle up and let’s dive into the world of isolators and switches!

Battery Isolators – The Unsung Heroes

You know what’s worse than a dead battery? Two dead batteries! That’s where battery isolators come in handy. These nifty devices make sure that your starting battery stays charged and ready for action while your house battery powers all those gadgets and gizmos you love.

Picture this: you’re out camping in your RV, binge-watching your favorite show, and suddenly your engine won’t start. Bummer, right? Well, with a battery isolator in place, you can wave goodbye to such woes, as it keeps your starting battery separate from the house battery, preventing it from draining.

Selector Switches – The Masters of Choice

If battery isolators are the unsung heroes, selector switches are the masters of choice. They give you control over which battery to use and when. Whether you want to use a single battery or both, the selector switch puts the power in your hands (quite literally).

Imagine being the DJ of your own battery party, choosing which battery to crank up or when to go all out with both. Selector switches make this possible, ensuring you never miss a beat when it comes to managing your batteries.

The Dynamic Duo

So, by now, you must be thinking, “Wow, these battery isolators and selector switches sound fantastic!” And you’re absolutely right! When used together, they form a dynamic duo that helps you get the most out of your dual-battery system.

With an isolator keeping your starting battery in tip-top shape and a selector switch giving you the freedom to choose, you’ll have a smooth and hassle-free experience, whether you’re on a boat, in an RV, or out conquering the wilderness.

And that, my friend, is the electrifying truth about the importance of using a battery isolator or selector switch! Don’t forget to give these marvelous devices the credit they deserve when setting up your next dual-battery system. Happy battery managing!

Dual 12/24V System

For applications requiring both 12V and 24V power sources, a dual 12/24V system can be created using a Littelfuse continuous-duty solenoid. This clever device switches between series and parallel connections, allowing you to utilize both voltages from the same battery bank. Talk about convenience!

Use Cases for a Dual 12/24V System

Some common use cases for a dual 12/24V system include:

  1. Recreational vehicles and boats with mixed-voltage appliances and electronics
  2. Off-grid solar power systems
  3. Industrial equipment requiring different voltage levels

01. Recreational Vehicles and Boats with Mixed-Voltage Appliances and Electronics

Recreational vehicles (RVs) and boats often contain a mix of 12V and 24V appliances and electronics, which require a versatile power system. Some common examples of mixed-voltage appliances and electronics include:

  1. 12V appliances: Lights, fans, water pumps, and refrigerators
  2. 24V appliances: Winches, bow thrusters, and larger motors for various onboard systems
  3. Electronics: Navigation systems, communication devices, and entertainment systems that may require different voltages

To accommodate these mixed-voltage devices, RV and boat owners can set up a dual 12/24V system using a continuous-duty solenoid, as mentioned earlier. This approach allows them to switch between series and parallel connections depending on the voltage requirements of the appliances and electronics in use.

02. Off-Grid Solar Power Systems

Off-grid solar power systems are becoming increasingly popular for providing electricity to remote locations, such as cabins, tiny homes, and even entire communities. These systems require a reliable energy storage solution, and connecting multiple batteries in series or parallel is often the answer. Here’s how it works:

  1. Solar panels: Solar panels convert sunlight into electricity, generating direct current (DC) voltage.
  2. Charge controller: The charge controller manages the flow of electricity from the solar panels to the battery bank, preventing overcharging and optimizing the charging process.
  3. Battery bank: The battery bank stores the electricity generated by the solar panels. Connecting batteries in series increases the system voltage, while connecting them in parallel increases the capacity, allowing for longer storage and usage times.
  4. Inverter: The inverter converts the DC voltage from the battery bank into alternating current (AC) voltage, which is suitable for powering household appliances and electronics.

By connecting batteries in series or parallel, off-grid solar power systems can be customized to meet the specific voltage and capacity requirements of each unique setup.

03. Industrial Equipment Requiring Different Voltage Levels

In the industrial sector, various equipment and machinery require different voltage levels to operate efficiently. For instance:

  1. Motors: Electric motors come in various sizes and power ratings, with voltage requirements ranging from 12V to 480V or even higher. Connecting batteries in series can help supply the necessary voltage to power these motors.
  2. Control systems: Industrial control systems, such as programmable logic controllers (PLCs) and sensors, often operate at lower voltages, such as 12V or 24V. A series or parallel battery configuration can be used to supply the correct voltage level.
  3. Lighting: Industrial lighting systems, including emergency lighting and backup power sources, may require different voltages depending on their design and purpose. Batteries connected in series or parallel can provide the appropriate voltage levels to keep the lights on when needed.

By understanding the voltage requirements of various industrial equipment and configuring batteries accordingly, businesses can ensure their machinery and systems operate efficiently and reliably.

Examples of Dual-Battery Use

After discussing the concept of dual-battery use, let’s delve into the various applications where multiple batteries are employed, showcasing the versatility and practicality of these setups across different industries and use cases.

A. Different Applications Where Multiple Batteries Are Used

Connecting multiple batteries in series or parallel can be useful in a variety of applications:

  1. Solar power systems for energy storage
  2. Backup power supplies during outages
  3. Electric vehicles and golf carts
  4. Marine and RV power systems

01. Solar Power Systems for Energy Storage

Energy storage is a critical component of solar power systems, as it allows excess electricity generated during periods of sunlight to be stored for later use. Batteries play a vital role in these systems, providing efficient and reliable energy storage solutions. Here’s a breakdown of how they work in solar power systems:

  1. Solar panels: These convert sunlight into direct current (DC) electricity, which is then sent to a charge controller.
  2. Charge controller: This device regulates the flow of electricity from the solar panels to the batteries, ensuring they are charged efficiently and preventing overcharging.
  3. Battery bank: The battery bank stores the electricity generated by the solar panels. Batteries can be connected in series to increase the system voltage or in parallel to increase the capacity, depending on the specific requirements of the solar power system.
  4. Inverter: This device converts the stored DC electricity from the batteries into alternating current (AC) electricity, which can then be used to power appliances and electronics.

02. Backup Power Supplies During Outages

Backup power supplies are essential during power outages, providing a reliable source of electricity to maintain essential services and prevent disruption. Batteries are often used in these backup power systems for their ability to store and deliver electricity when the main power grid fails. Some common examples of backup power systems include:

  1. Uninterruptible Power Supply (UPS): A UPS system provides short-term power to sensitive electronics, such as computers and data centers, during power outages or fluctuations. These systems usually consist of one or more batteries connected in series or parallel to provide the necessary voltage and capacity.
  2. Emergency power generators: These devices use batteries to start the generator engine, which then produces electricity to power essential services and equipment during an outage. The batteries are often connected in series to supply the required starting voltage for the generator.

03. Electric Vehicles and Golf Carts

Electric vehicles (EVs) and golf carts rely on battery banks to store and deliver electricity for propulsion. These vehicles typically use multiple batteries connected in series or parallel to achieve the desired voltage and capacity levels. The configuration of the battery bank is crucial for the vehicle’s performance, as it determines the available driving range and power output. Some key components of EV and golf cart battery systems include:

  1. Battery pack: The battery pack consists of multiple batteries connected in series or parallel to provide the required voltage and capacity for the vehicle’s propulsion system.
  2. Battery management system (BMS): The BMS monitors the health and performance of the battery pack, ensuring it operates efficiently and safely. It also manages the charging and discharging processes, optimizing the battery’s lifespan.
  3. Electric motor: The electric motor converts the stored electricity in the battery pack into mechanical energy, which powers the vehicle’s wheels.

04. Marine and RV Power Systems

Marine and RV power systems rely on batteries to provide electricity for various onboard systems and appliances. These batteries are often connected in series or parallel configurations to meet the specific voltage and capacity requirements of each application. Some examples of marine and RV power systems include:

  1. House batteries: These batteries power the onboard appliances and electronics, such as lighting, refrigeration, and entertainment systems. They are typically deep-cycle batteries connected in series or parallel to provide the necessary voltage and capacity.
  2. Starting batteries: Starting batteries are used to start the engine of the boat or RV. These batteries often have a higher cold-cranking amp (CCA) rating and are connected in series to provide the required starting voltage.
  3. Dual-battery systems: Some marine and RV power systems use a combination of house and starting batteries, with a battery isolator or selector switch to manage their charging and discharging processes. This setup allows for
  4. the efficient use of available power and ensures that the starting battery remains charged for its primary purpose.
  5. Charging systems: Marine and RV power systems require a reliable method of recharging the batteries to ensure ongoing power availability. Common charging systems include alternators, solar panels, and shore power connections. These systems replenish the energy used by the onboard systems and appliances, keeping the batteries charged and ready for use.
  6. Inverters: Inverters convert the DC electricity stored in the batteries into AC electricity, which is required for many onboard appliances and electronics. Depending on the power needs of the marine or RV system, inverters can range from small, portable units to large, high-capacity models.

By understanding the unique power requirements of marine and RV systems, owners can configure their battery banks appropriately, ensuring reliable and efficient performance in various situations. Connecting batteries in series or parallel allows for customization of the power system to meet the specific voltage and capacity needs of each application, providing a versatile and reliable source of electricity on the go.

B. Advantages and Disadvantages of Using Multiple Batteries in Parallel or Series


  • Series connections increase the output voltage, useful for 24V applications
  • Parallel connections increase the capacity, providing longer runtime for 12V systems


  • Series connections do not increase capacity, limiting the runtime
  • Parallel connections do not increase voltage, limiting their usefulness for higher-voltage applications


We’ve covered the essentials of connecting two 12V batteries to make a 24V system, including the required tools, step-by-step instructions, and even some examples of dual-battery use. You’re now equipped to tackle any battery-related challenge that comes your way!

Always remember to prioritize safety when working with electricity. Use appropriate protective gear, double-check your connections, and follow the guidelines for disposing of used batteries and other materials.

Connecting two 12V batteries to make a 24V system can unlock new possibilities for various applications. With this newfound knowledge, you’re ready to power your adventures, projects, or off-grid endeavors. Now, go forth and electrify your world.


What happens when you connect two 12 volt batteries in parallel?

Connecting two 12V batteries in parallel maintains the same voltage (12V) while doubling the capacity (Ah) for longer usage.

Can you charge 2 12V batteries with 24V?

Charging 2 12V batteries with 24V isn’t recommended, as it may overcharge and damage them. Use a proper charger designed for parallel charging.

Can you convert 12 volt to 24 volt?

Converting 12V to 24V requires a DC-DC step-up converter, which increases the voltage while decreasing the available current proportionally.

How many 2v batteries does it take to make 24V?

It takes twelve 2V batteries connected in series to make a 24V battery.

Will 2 12V batteries in parallel last longer?

Yes, 2 12V batteries in parallel will last longer due to doubled capacity (Ah), while maintaining the same voltage (12V).

How many volts will two 12v batteries connected in series output?

Two 12V batteries connected in series will output 24 volts, as the voltages add up in a series connection.

How many double A batteries does it take to make a 12 volt battery?

It takes eight 1.5V AA batteries connected in series to make a 12V battery.

How many 12V batteries does it take to make 48v?

To make 48V, four 12V batteries connected in series are required, as the voltages add up in a series connection.

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