We all use batteries in typical day-to-day life. Whether it be in our remote control, watch, car, or RV, batteries are a part of our lives. Most of the time, we don’t need to think about the voltage of a battery. However, when working with DC power systems for RV’s boats or off-grid applications, a serious decision needs to be made between 12V vs 24V.
This article will discuss 12V and 24V systems and the differences in 12V vs 24V batteries. Let’s get into it!
What is the Voltage of a Car, RV, or Boat Electrical System?
Most cars, RVs, and boats utilize a 12-volt electrical system, although there are some exceptions. So, when are 12V vs 24V batteries used?
To understand more about batteries, we must first understand what volts or voltage is. Voltage is the amount of electrical pressure it takes to push an electrical current. Take a look at what volts are to get a better understanding of this concept.
What Does “12V” Mean?
12V tells us that the battery supplies 12 volts under a nominal load. The same principle holds for a 24V battery bank in that it provides 24 volts.
As we discussed before, most car and RV batteries are 12V.
12V batteries are used in most vehicles because the electrical components such as the starter, lighting, and ignition systems are designed to operate on 12 volts.
We sometimes use 24V battery systems in larger trucks and busses due to the vehicle’s higher power needs and long cable runs. You can also see 24V used in larger boats and some RVs with elaborate solar systems.
Another typical application for a 24V system is on trolling motors for fishing boats.
How is a 24V System Made?
A 24V system is where you produce 24V under nominal load. There are a couple of ways to create a 24V power system. One way is to purchase a 24V battery. The other is to use two 12V batteries in series to create a 24V system. Let’s take a look at these options in a little more detail.
What is a 24V Battery?
One way to create a 24V system is to use a 24V battery. 24V batteries are less common than their 12V counterpart and are harder to come by. 24V batteries are also relatively expensive.
However, they do take up less space than running other batteries in series. So, if space is a concern, a single 24V battery may be a better choice for you.
How Do You Connect 12V Batteries In Series?
The most common method for building a 24V system is to run batteries in series.
Running batteries in series means they have a single electrical path equal to the sum of the system’s volts. So, if you have two 12V batteries wired in series, then 2x12V=24V.
To create a 24V system using two 12V batteries, you would wire the first battery’s “+” positive terminal to the “-“negative terminal of the second battery. The remaining negative and positive connections get wired to the component you want to power just as you would if you were using a single battery. You can accomplish the same thing using four 6 volt batteries.
To make this easier to digest, let’s look at something we are all familiar with, a flashlight. Many flashlights use batteries that are running in series. Suppose you have a large flashlight that uses four “C” size batteries.
When you install the batteries, they are in a single row with negative touching positive. This is a series circuit. Each of the “C” batteries is 1.5V. We learned earlier that when batteries run in series, then the output voltage is the sum. In this case, the flashlight runs off 6 volts.
Comparing 12V vs 24V – Benefits of Each
When looking at 12V vs. 24V systems, there are some pros and cons to each system type. Let’s take a look at some of the pros of each.
12V System Benefits
As we talked about earlier in the article, 12V systems are relatively common. Most vehicles use 12V systems as components used in vehicles are designed to operate on 12V. The alternators generate 12V to charge the battery.
When it comes to RVs, most appliances such as RV refrigerators and all the lighting work on 12V as well. 12V systems only require one battery and work well for low-power applications and short wire runs.
24V System Benefits
24V systems are beneficial because you can use smaller diameter wire and reduce amperage by two times. Using smaller diameter wire can reduce wiring costs and decrease the space needed to run wiring. This is especially important where long wire runs are required.
But wait, how can you run a smaller wire with more voltage?
You can actually run a wire 2x smaller than an equivalent 12V circuit. This is because the higher voltage requires less current to produce the same power. Since we are running less current or amps, we can use a smaller wire. This is the same reason power is transmitted on power lines at very high voltages. The wires can be much, much smaller and carry lots more power!
In addition to smaller wires, 24 volt systems operate more efficiently in motors and inverters. Often, the same solar charge controller operating on 24V vs 12V will handle twice the solar input.
Comparing 12V Vs 24V Cons of Each
As there are pros of 12V vs 24V systems, there are also cons to each type of system. Some of the pros of one system can become a con of the other.
Downsides of 12V
12V systems require massive wires when pulling large loads because the current (amps) are higher. As we have already learned, 24V systems reduce the current or amps two times, then a downside of a 12V system is the amperage is double that of a 24V system at the same power.
Because 12V batteries use two times the amperage at a given power draw, they are less efficient than a 24V battery due to resistive losses.
Downsides of 24V
If you are using a 24V system in an application with 12V appliances, you will need a converter to reduce the voltage to 12V. The variety of components and devices that run on 24V are not as plentiful as what is available in 12V.
Although you can charge a 12V battery with the alternator of a vehicle, you won’t be able to do that with a 24V system if the chassis is a 12V system. Additional DC-DC converters are needed to accomplish this task.
When To Use A 12V vs 24V System
Now that we have learned a little about 12V vs. 24V systems, we need to understand when we should use one over the other.
When building a DC (direct current) battery system, it’s crucial to understand your power requirements to run the appliances you need. The energy that is consumed by a device is measured in watts. Once you know your wattage requirement, you can determine what system is required.
If your requirements are below 3000W, you can generally get by with a 12V system.
Many recommend 24V systems when your power needs are above 3000W or generating 3000W of solar or more. When you get to this point, the benefits of a 24V system outweigh the cons because you can run smaller and increase the system’s efficiency.
If your power consumption is even higher, above 6000W, you can benefit from an even larger DC system and consider stepping up to 48V.
24V DC Benefits For Solar
Many DC MPPT solar charge controllers have higher voltage capabilities to handle higher panel voltages. They, however, have a hard current limit.
When using a 50 amp rated charge controller on a 12V battery bank, you can use the controller with 700 watts of solar. If you use that same charge controller on a 24V battery system, it can connect to 1400 watts of solar panels. This means that half the number of solar charge controllers is needed. They will also operate more efficiently at 24 volts.
12V vs 24V, Which Is Right For Me?
It isn’t always a clear-cut decision. There are many variables to consider when determining which one is the best choice.
Now that we understand these systems better, they are not as intimidating as we originally thought them to be. Whether you end up with a 12V or 24V system, you now understand the differences. You can assess your needs and make an educated decision.
Want To Learn More About Electrical Systems and Batteries?
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