Parallel, series, alone, etc! There are a lot of different ways to configure your battery system and figuring out how you want to hook them up often brings about this question: What are the differences between 12V and 6V batteries? Here’s the run down on what makes them different, and how they work!
Makeup and How They Work
A battery is full of cells with chemicals that transfer ions back and forth to create electricity. Each cell in a deep-cycle battery can produce about 2 volts. A 6V battery has 3 cells, making a total of 6 volts, and a 12V battery has 6 cells, making a total of 12 volts! In order to really understand how this comes into play, you have to understand voltage and what it does.
The voltage is the force by which the electricity is moved. The plates inside the battery push electrons from one side to the other. The higher the voltage in the battery, the stronger that push is. Imagine a hose faucet. When you turn it on only a little, the water is only pushed lightly to the end of the hose. If you turn it on all the way, the water is forcefully pushed to the end of the hose. You then get more water at a faster rate. When calculating voltage, it is always represented by a capital V. You will need to remember this for later as we discuss how the RV system works and how to connect the batteries to get the best set up.
The current that comes from the battery is the flow of the electrons. Remember that the voltage is what is pushing it, so the current is the actual movement of it. Referring back to the hose, where the voltage is the faucet and how high it’s turned up, the water moving through the hose is the current. You will often times see things refer to amps, and this is the measurement of the current. When calculating current it is always represented as an uppercase I. Keep that in mind as well for the next section.
Some things can disrupt current in the same way things can disrupt water flow. A kink or clog in a hose doesn’t change the pressure at the faucet, but it does slow the amount of water coming through the end of it. Things such as damaged wires can slow the current much in the same way. This is the resistance found. The size of the wire is usually where you’ll find the most resistance. You may have noticed that the smaller a wire is, the higher the number of “gauge” it is. This is because that number isn’t representing the size of the wire, but the amount of resistance the wire is giving the current.
The result of the voltage pushing the current is the power. Examples include lights that come on as current rushes into the filament, or a TV showing the picture as it rolls through its circuit boards, and so on. Increasing either the current or voltage will get you more power. Power is measured in watts, and denoted as a capital P when we work though the equation.
Figuring out how much power you need is helpful when figuring out how to connect your batteries, and which ones to use. We’re going to brush off some of our old math skills for this one. Remember the letters we talked about in the last few sections:
V = Voltage
I = Current
P = Power (in watts)
Let's use a simple example of a light bulb. For this example, let's say you want to power a 60-watt light bulb with a 6V battery. What we need to know is the current needed to make it happen. Current is calculated by dividing the power by the voltage. So for this example, the equation would look something like:
60P/6V = 10 amps (or 10I)
Now let's take a look at this same equation, but using a 12V battery!
60P/12V = 5 amps (or 5I)
This has cut the current needed to power the bulb in half. This is an exceptionally great thing if you experience a lot of resistance in your wires. The electrical system is now more efficient and your battery will last longer.
We now know that higher voltage is more efficient. So how can you link your batteries together to get the most efficiency? There are a few different ways to do it that will yield different results. Let’s take a look and see what happens!
Linking your batteries in a series will double your voltage! This is how you can get a 12V system out of two 6V batteries. Basically you want to link them so that they run together as one. To hook this up, you’ll have battery A and battery B, just so that it’s less confusing. Begin with battery A and hook the positive post to the RV system. Hook the negative post from battery A to the positive post of battery B. The negative post of battery B is then connected to the ground. This now offers the same current but at a higher voltage as both batteries are using their cells to push the current.
Linking your batteries in a parallel way will simply increase the capacity of your system. This will not affect voltage but will allow you to have more hours on your system without having to change over a battery. Link the positive cable of battery A to the positive cable of battery B, then likewise with the negative. Now run a cable from battery B’s positive post to the RV system and the negative post to the ground. Only link batteries with the same voltage in a parallel system.
So what do you do if you have four 6V batteries, you want to run them at 12V, but don’t want to have to change them over when one set runs low? You run a parallel series!
We now have batteries A, B, C, and D. Connect the positive post of battery A to the RVs system and the negative post to battery B’s positive post. Link battery B’s negative post to the ground. Connect battery C’s positive post to the positive post of battery A, and the negative post should link to the positive post of battery D. Then link the negative post of battery D to the negative post of battery B.
You now have a few options on how to use batteries together, depending on the goal you wish to reach. Let us know what kind of setup you’re using!