As RVers, we rely heavily on our battery banks to power our electrical systems while off-grid. However, it can be confusing to understand how much capacity our battery banks actually have. In this article, we’ll discuss the importance of understanding battery bank capacity and how to calculate it.
Amp Hours Explained – Video
How Parallel Battery Wiring Affects Amp Hours
Let’s start with parallel wiring. When two 100-amp-hour batteries are wired in parallel, their amp hours get added together while their voltage remains the same. This means that we now have 200 amp hours of battery bank capacity at 12.8 volts. It’s important to note that when batteries are wired in parallel, the positive terminals are connected to each other, and the negative terminals are connected to each other.
How Parallel Battery Wiring Affects Amp Hours
On the other hand, when two 100-amp-hour batteries are wired in series, their voltages get added together, and their amp hours remain the same. This means that we now have a nominal 24-volt battery bank and a 100-amp-hour battery bank. In series wiring, the positive terminal of one battery is connected to the negative terminal of the other battery, and the remaining positive and negative terminals are connected to the system.
Battery Voltage Does Not Affect Capacity
It’s a common misconception that a battery bank wired in parallel has more capacity than a battery bank wired in series. However, this is not the case. Both battery banks have the same amount of capacity, regardless of whether it’s being delivered at 12.8 volts or 25.6 volts. To understand why, we need to use the formula amp hours times volts equals watt hours.
Understanding Watt Hours
A watt hour is a unit of energy that measures the amount of power used by an electrical device over one hour. To calculate watt hours, we use the formula amp hours times volts equals watt hours. So, for example, 200 amp hours times 12.8 volts equals 2.56 kilowatt hours or 2,560 watt hours. The same calculation for a 100-amp-hour battery bank operating at 25.6 volts will also result in 2,560 watt hours.
Amp Hours vs Watt Hours – An Example
To understand how much power is being used by an electrical device, we need to calculate the amps flowing from the battery bank to the device. We can use the formula watts equals amps times volts to do this. For example, a 100-watt light bulb operating at 12.8 volts will pull 7.81 amps from the battery bank. The same light bulb operating at 25.6 volts will pull 3.90 amps from the battery bank.
Voltage’s Role in System Design
The difference in voltage can play a huge role in system design and how we choose to power different loads. Choosing appliances that operate at a higher voltage paired with a matching power supply or battery bank can allow us to use smaller wires because the amperage is less. This is one of the reasons why a 24-volt battery bank may be more advantageous in certain situations.
Amp Hours Explained – Conclusion
In conclusion, understanding battery bank capacity and how it is affected by wiring and voltage is crucial for off-grid RVers. Knowing how to calculate power usage and watt hours can help you better understand your energy needs and make informed decisions about your electrical system design.
