At Enexer, we believe knowledge is power, quite literally. Whether you're building your first off-grid solar setup, upgrading your RV’s electrical system, or experimenting with lithium iron phosphate (LiFePO4) batteries for a home project, understanding the basic principles of electricity is essential.
This article breaks down the core electrical concepts: voltage, amperage, power, capacity, watt-hours and helps understand how they relate to real-world battery applications.
Voltage (V): The Electrical Pressure
Voltage is often described as the "pressure" that pushes electrical current through a circuit. Think of it like water pressure in a pipe, the higher the pressure, the more water (or electricity) that can move.
- Unit: Volts (V)
- What it tells you: How strong the electrical force is.
- Why it matters: A typical 12V LiFePO₄ battery has a nominal voltage of 12.8V, which is safe and efficient for powering small electronics, lighting, or DC appliances. Matching voltage to your devices is crucial for system compatibility and protection.
Example:
If you're running a 12V LED light strip, you need a battery that matches this voltage. Using a 24V battery without a converter would overpower and likely damage the lights.
Amperage (A): The Flow of Current
Amperage, or current, is the flow rate of electricity. Going back to the water analogy, this is how much water flows through the pipe at a given moment.
- Unit: Amperes or Amps (A)
- What it tells you: How much electricity is flowing.
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Why it matters: A battery rated for 100A continuous discharge can safely deliver that amount of current without overheating or degrading. Understanding current draw ensures your system components are properly sized and protected.
Example:
If you're powering a small inverter that draws 50A from a 12V battery, you must ensure your battery and wiring can handle that current safely.
Power (W): Voltage x Amperage
Power is the rate at which energy is used or produced. It’s a product of voltage and current:
Power (Watts) = Voltage (V) x Amperage (A)
- Unit: Watts (W)
- What it tells you: How much energy a device consumes or how much a battery can deliver at a given moment.
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Why it matters: Power ratings help you determine what size of battery or inverter you need for specific appliances. It also helps prevent overloads and manage energy budgets.
Example:
If your fridge is rated for 240W and you're using a 12V battery, it will draw approximately 20A (240W ÷ 12V). That’s important to know when selecting cables, circuit protection devices, distribution equipment, and batteries.
Capacity (Ah): How Long It Lasts
Capacity measures how much charge a battery can hold. It’s typically rated in amp-hours (Ah), indicating how many amps the battery can supply for how many hours.
- Unit: Amp-hours (Ah)
- What it tells you: The energy storage of a battery over time.
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Why it matters: A 100Ah battery can theoretically deliver 100 amps for 1 hour - 10 amps for 10 hours. Knowing capacity helps estimate runtime and plan for energy needs.
Capacity describes current over time, but not the complete energy picture. That’s where watt-hours come in.
Watt-Hours (Wh): Total Energy Stored
Watt-hours represent the total amount of energy a battery can store or deliver over time. It's a combination of both voltage and capacity:
Watt-hours (Wh) = Voltage (V) x Amp-hours (Ah)
- Unit: Watt-hours (Wh)
- What it tells you: The total usable energy in a battery.
- Why it matters: Watt-hours give a fuller picture of energy storage than amp-hours alone. They help compare different battery systems and predict how long devices can run.
Example:
A 12V 100Ah Enexer LiFePO₄ battery stores nominally 1,280Wh (12.8V x 100Ah) of energy.
That’s enough to power a 100W device for approximately 12.8 hours (1,280Wh ÷ 100W).
Bringing It All Together
Let’s consider a practical use case, you want to power a portable fridge that uses 60W, running on a 12V system.
- Current draw: 60W ÷ 12V = 5A
- Runtime with 100Ah battery: 100Ah ÷ 5A = ~20 hours
- Total energy used: 60W x 20h = 1,200Wh
With a 12V 100Ah Enexer LiFePO4 battery, you'd have just the right amount of energy storage to run the fridge continuously for about 20 hours.**
**Please note, this sample calculation is for reference only to demonstrate and help understand the key electrical principles discussed. It does not consider additional factors such as losses, equipment efficiencies, depth of discharge, etc.
Why This Matters
Understanding these fundamentals allows you to:
- Size your battery bank correctly
- Avoid overloading your system
- Choose compatible devices and components
- Optimize your power use for maximum efficiency and safety
Whether you're designing a solar-powered tiny home or upgrading your boat’s electrical system, the principles of voltage, current, power, and capacity are the building blocks of any successful setup.
Always remember to follow all applicable local safety code requirements, laws, and regulations for a safe and functional electrical system.
Learn More with Enexer
At Enexer, we specialize in reliable, safe, high-performance LiFePO4 batteries designed for many applications such as renewable energy, mobile applications, and DIY energy solutions. Our products are engineered to deliver consistent voltage, handle high current loads, and offer long-lasting capacity, all without compromising safety and backed by expert support.
Explore our LiFePO4 battery lineup or contact us for guidance on building your custom system.
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