Power & Current Basics

AC (Alternating Current)

This is the type of electricity used in homes and mains power. It changes direction periodically and is what comes out of standard wall sockets.

DC (Direct Current)

This is the type of electricity used in 12V systems. It flows in one direction and is what your battery supplies to your gear—like your fridge, lights, and USB chargers.

Ah (Amp Hours)

A measure of a battery’s capacity. A 100Ah battery can, in theory, provide 100 amps for one hour or 10 amps for 10 hours. This tells you how long your battery can run your gear before needing a recharge.

Wh (Watt Hours)

Another way to measure battery capacity, but in terms of power usage over time. It’s calculated as volts × amp hours (V × Ah = Wh). For example, a 12V 100Ah battery has 1,200Wh of stored energy.

mAh (Milliamp Hours)

Used for small batteries, like those in power banks and phones. A 10,000mAh battery means it can theoretically supply 10 amps for 1 hour, or 1 amp for 10 hours.

A (Amps) & mA (Milliamps)

Amps measure how much electrical current is flowing. 1,000mA = 1A. If a fridge draws 5A per hour, a 100Ah battery could run it for around 20 hours (without considering power loss).

Solar & Charging Terms

PV (Photovoltaic)

Refers to solar panels, which convert sunlight into electricity. If you see "PV input" on a device, it means it accepts power directly from solar panels.

MPPT (Maximum Power Point Tracking)

A type of solar charge controller that improves efficiency, extracting more power from solar panels by optimising voltage. If you want to get the most out of your solar panels, an MPPT controller is the way to go.

PWM (Pulse Width Modulation)

Another type of solar charge controller, but less efficient than MPPT. It works by reducing voltage to match the battery, which can waste some solar power. It’s cheaper but not ideal for larger setups.

AWG (American Wire Gauge)

The standard for measuring wire thickness. In 12V setups, using the correct wire gauge is critical to prevent voltage drop and overheating. Lower AWG numbers mean thicker wire—for example, 8AWG is much thicker than 16AWG.

Appliance & Electrical Terms

Hz (Hertz)

The frequency of AC power. In Australia, the mains electricity runs at 50Hz, meaning it cycles 50 times per second.

V (Volts)

A measure of electrical pressure. A 12V system means everything is designed to run at 12 volts. Some inverters step this up to 240V for running household appliances.

W (Watts)

Measures power consumption. If a fridge uses 60W, it means it needs 60 watts of power per hour to run. The formula to calculate this is:

• Watts = Volts × Amps (W = V × A)

Final Thoughts

When you’re setting up your 12V off-grid system, understanding these acronyms will make it so much easier to choose the right gear and avoid common mistakes. Whether you’re sizing up a battery, picking a solar charge controller, or running cables, these terms will help you power your next adventure like a pro!