DC power explained. What do all the terms mean?

DC power explained

DC (Direct Current) power is electricity that flows in one constant direction.

Think of it like water flowing through a hose in a steady stream — it doesn’t change direction or pulse back and forth.

• Batteries produce DC power
• Solar panels produce DC power
• Most 12V systems (like in cars, caravans, and 4WD setups) use DC power

The 3 key parameters: Volts, Amps, and Watts

The easiest way to understand these is with a water analogy:

Volts (V) — “Pressure”

Voltage is the push behind the electricity. Like water pressure in a pipe,

• Higher water pressure = stronger push –> Higher volts = stronger push

Example:

• A 12V battery pushes electricity gently
• A 240V household outlet pushes much harder

Amps (A) — “Flow rate”

Amps measure how much electricity is actually flowing.

• Like how much water is flowing through the pipe
• Higher amps = more flow

Example:

• A small LED light uses very few amps
• A fridge or compressor draws more amps

Watts (W) — “Total power”

Watts tell you the total amount of work being done.

• Like how powerful the water flow is overall, how much work it can achieve
• It combines volts and amps; if you double the voltage you only need half the current (amps), and vice versa.

Simple formula:

Watts = Volts × Amps

Example:

• 12V × 5A = 60W
• 12V × 10A = 120W

So doubling the amps or doubling the voltage, doubles the power.

Putting it all together

Think of a 12V camping setup:

• Volts (12V) = the system pressure
• Amps (e.g. 5A) = how much current your device draws
• Watts (60W) = the actual energy being used

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For e.g. A 12V fridge might use:

• 12 volts
• 4 amps

So:

• 12 × 4 = 48 watts

That’s the instantaneous power it needs to run.

Want to calculate how much power your system needs? Try our 12V battery calculator! It helps you calculate total power over time, not just instantaneous Watts, but Watt Hours (Wh) or KiloWatt Hours (kWh). These are the values you need to determine what size battery you need. It will also help you convert that into Amp Hours, which are also a common battery term used to explain the capacity of some batteries.

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• 12V Battery Calculator
• 12V Cable Calculations
• DC power explained. What do all the terms mean?