Caravan Power Terminology Explained: Your Guide to 12V, Ah, W, kWh and Inverters

Q: How do I calculate kWh from my battery's Ah rating?

Multiply your battery&amp;#39;s Amp-hour rating by its voltage, then divide by 1,000. For a 12V system with a 100Ah battery: (100Ah × 12V) ÷ 1,000 = 1.2 kWh of total stored energy. Remember that usable capacity depends on battery type—lithium allows 80–100% discharge while AGM batteries should only be drawn to 50% to preserve lifespan.

Updated on: January 22, 2026

There's a particular silence that every caravanner dreads—the moment your camp fridge stops humming at a remote campsite. The snags are half-cooked, the sun's going down, and you're suddenly confronting a power system you never quite understood.

The good news? You only need to grasp a handful of terms to take complete control of your caravan's electrical setup. This Outbax guide breaks down the essential terminology—12V, Ah, W, kWh, and inverters—so you can confidently size your battery bank, choose the right 12V inverter, and keep everything running when you're far from the nearest powered site.

VoltX 12V 1KW Pure Sine Wave Inverter + FREE VoltX Inverter LCD Display

The Core Four: Must-Know Power Terms

Before diving into batteries and inverters, it helps to understand the four fundamental units that govern every caravan electrical system.

Volts (V): The Pressure in Your System

Voltage is electrical pressure—the force pushing electrons through your wiring. Think of it like water pressure in a garden hose. Most caravan systems operate on a 12V standard, which matches your vehicle's battery and allows seamless integration with automotive charging systems.

VoltX 12V 100Ah Lithium LiFePO4 Battery

Amp-Hours (Ah): Your Fuel Tank Capacity

Amp-hours measure your battery's storage capacity, much like litres measure a fuel tank. A 100Ah battery can theoretically supply 1 amp for 100 hours, or 10 amps for 10 hours. This rating tells you how long your appliances can run before the battery needs recharging.

Watts (W): The Rate of Power Use

So, what is a watt exactly? Watts measure instantaneous power consumption—how much energy an appliance draws at any given moment. Using the hose analogy, watts represent how fast water flows out. Every appliance displays its wattage on a label or in its manual; a compressor fridge might draw 50W, while a microwave could pull 1500W.

Kilowatt-Hours (Kwh): Total Energy Consumed

Kilowatt-hours represent cumulative energy use over time—exactly what your electricity retailer bills you for at home. The formula is straightforward:

(Watts × Hours) ÷ 1000 = kWh

Running that 50W fridge for 24 hours consumes 1.2 kWh. Understanding this calculation helps you plan multi-day trips without unexpected power shortfalls.

Choosing Your Power Source: A Guide to Caravan Batteries

Deep cycle batteries form the heart of any off-grid setup. Unlike starter batteries designed for short, high-current bursts, deep cycle units deliver steady power over extended periods. Two technologies dominate the Australian caravan market.

Lithium (LiFePO4) Batteries: The Modern Powerhouse

Lithium iron phosphate batteries have transformed caravan electrical systems. Their advantages include:

Lighter weight — roughly half the mass of equivalent AGM units
Longer lifespan — 2,000 to 5,000 charge cycles versus 300–500 for AGM
Deeper safe discharge — usable capacity of 80–100% without damage
Faster charging — accepts higher charge currents for quicker turnaround
Built-in protection — Battery Management Systems (BMS) prevent overcharging, over-discharging, and overheating

Many lithium batteries like the VoltX 12V 100Ah Bluetooth Daly Lithium LiFePO4 Battery now include Bluetooth monitoring, letting you check the state of charge from your phone. The higher upfront cost—typically two to three times that of AGM—pays back through longevity and reduced replacement frequency.

VoltX 12V 100Ah Bluetooth Daly Lithium LiFePO4 Battery

Here’s what one of our customers said:

“This is my 2nd purchase of this type of battery from Outbax. These 2 are for my caravan, I have a 300amp which is now 3+ years old and still going strong in the 4WD.”

AGM Batteries: The Reliable Workhorse

Absorbent Glass Mat batteries remain popular for good reasons. They're more affordable initially, perform reliably across varied temperatures, and require no maintenance. However, AGM units come with trade-offs:

Heavier construction — significant weight penalty in multi-battery setups
Shorter cycle life — expect 300–500 cycles under typical use
Shallower discharge — manufacturers recommend drawing only 50% capacity to preserve lifespan

To achieve the same usable power, an AGM battery bank needs roughly double the rated capacity of a lithium equivalent. This translates to higher accumulated costs over time, especially for avid adventurers.

Converting Power Safely: Understanding Caravan Inverters

Your battery bank stores 12V DC (direct current), but most household appliances require 240V AC (alternating current). That's where inverters come in.

What Does a 12V to 240V Inverter Do?

A 12V to 240V inverter transforms your battery's DC power into the same AC electricity available from wall sockets at home. This lets you run everything from phone chargers to coffee machines while camped off-grid.

Pure Sine Wave vs Modified Sine Wave: A Critical Choice

Not all inverters produce equal power quality, and choosing incorrectly can damage expensive equipment.

Pure sine wave inverters like the VoltX 12V 1KW Pure Sine Wave Inverter generate smooth, grid-identical electrical output. They're essential for:

Laptops and tablets
Modern televisions
CPAP machines
Microwave ovens
Variable-speed power tools

Modified sine wave inverters cost less but produce a stepped, choppy waveform. They're adequate for simple resistive loads—basic heaters, incandescent globes, or simple fan motors—but can cause buzzing, overheating, or outright failure in sensitive electronics. For most modern caravanners, a pure sine wave model is the only sensible choice. The price premium protects gear worth far more than the inverter itself.

Here’s what one of our customers said:

“Purchased a 12V to 240V Inverter. The product is easy to use and works perfectly. Overall it was an economical solution to fulfill our needs.”

Putting It All Together: A Practical Caravan Power Setup

Understanding terminology means little without practical application. Here's how to size your system correctly.

Step 1: Calculate Your Daily Power Consumption

Create a simple power audit by listing every appliance you'll use:

Note each item's wattage (check the label or manual)
Estimate daily hours of operation
Multiply watts by hours for each appliance
Total all figures for your daily Watt-hour (Wh) requirement

A typical setup might include a 50W fridge running 24 hours (1,200Wh), LED lights at 20W for 4 hours (80Wh), and phone charging at 10W for 3 hours (30Wh)—totalling approximately 1,310Wh daily.

Step 2: Sizing Your Battery Bank and Inverter

Convert your daily Wh requirement into Amp-hours: Wh ÷ 12V = Ah. That 1,310Wh example needs roughly 110Ah of usable capacity.

For lithium batteries with 100% usable capacity, a 120Ah unit provides comfortable headroom. For AGM batteries at 50% safe discharge, you'd need a 220Ah bank to access the same usable power.

Size your inverter above the total wattage of appliances you might run simultaneously. If you want to operate a 1500W microwave while the 50W fridge runs, you need a capacity exceeding 1,550W. A 2000W inverter 12V provides appropriate headroom.

Step 3: Keeping Your System Charged

Multiple charging methods keep your batteries topped up:

Alternator charging — replenishes batteries while driving via a DC-DC charger
Generator backup — useful during extended overcast periods
Solar panels — a 12V solar inverter system paired with panels delivers true off-grid independence

Outbax offers complete solar kits designed to integrate seamlessly with caravan battery systems, taking the guesswork out of component matching.

Final Thoughts on Your Caravan Power Setup

Mastering caravan power terminology transforms how you approach off-grid travel. The four foundational terms—volts, amp-hours, watts, and kilowatt-hours—give you the vocabulary to understand any system. Choosing between lithium and AGM batteries comes down to balancing upfront cost against long-term value. And selecting a pure sine wave inverter protects the electronics that make modern caravanning comfortable.

A quick power audit before each trip is your best insurance against flat batteries and ruined provisions. With the right knowledge and properly sized equipment from Outbax, those silent-fridge moments become a thing of the past—leaving you free to enjoy the campsite, the snags, and the adventure.

You can buy products from: Inverters

Frequently Asked Questions

What are deep cycle batteries actually used for?
Deep cycle batteries are designed to provide steady, sustained power over extended periods rather than the short, high-current bursts starter batteries deliver. In caravans, they power everything from fridges and lights to water pumps and entertainment systems during off-grid camping. Their construction allows repeated discharge and recharge cycles without the damage that would destroy a standard automotive battery.
Can a modified sine wave inverter really damage my appliances?
Yes, modified sine wave inverters can damage sensitive electronics. The stepped waveform they produce causes excessive heat in motors, creates audible buzzing in audio equipment, and can corrupt data in computers. CPAP machines, modern televisions, and microwave ovens are particularly vulnerable. While you might save $100–$200 upfront, repairing or replacing damaged appliances costs far more.
How do I calculate kWh from my battery's Ah rating?
Multiply your battery's Amp-hour rating by its voltage, then divide by 1,000. For a 12V system with a 100Ah battery: (100Ah × 12V) ÷ 1,000 = 1.2 kWh of total stored energy. Remember that usable capacity depends on battery type—lithium allows 80–100% discharge while AGM batteries should only be drawn to 50% to preserve lifespan.
What size inverter do I need for my caravan?
Your inverter must exceed the combined wattage of all appliances you'll run simultaneously. Add up the wattage of devices you might use at once—for example, a 1500W microwave plus a 50W fridge plus a 100W television equals 1,650W. Choose an inverter with at least 20% headroom above this figure, making a 2000W model the practical minimum for this scenario.
How do solar panels charge my 12V batteries?
Solar panels generate DC electricity when exposed to sunlight, but their output voltage varies with conditions. A solar charge controller sits between your panels and batteries, regulating voltage and current to safely charge without overcharging. MPPT (Maximum Power Point Tracking) controllers extract more energy from panels than simpler PWM controllers, particularly in variable light conditions.
What's the difference between Amp-hours (Ah) and Amps (A)?
Amps measure instantaneous current flow—how much electricity moves through a circuit at any given moment. Amp-hours measure capacity over time—how much current a battery can deliver for how long. A 100Ah battery supplying 10 amps would theoretically last 10 hours (100Ah ÷ 10A = 10 hours), though real-world factors like temperature and discharge rate affect actual performance.
Why are lithium batteries becoming so popular for camping?
Lithium batteries offer compelling advantages for weight-conscious travellers. At roughly half the weight of equivalent AGM units, they reduce payload significantly in multi-battery setups. Their 2,000–5,000 cycle lifespan dwarfs AGM's 300–500 cycles, and 80–100% usable capacity means a smaller lithium bank delivers the same practical power as a larger AGM installation. Built-in Battery Management Systems add safety features AGM lacks.
When is it okay to use a cheaper modified sine wave inverter?
Modified sine wave inverters work acceptably for purely resistive loads, like incandescent light bulbs, basic ceramic heaters, and simple heating elements. They're also adequate for universal phone chargers and basic power tools without electronic speed controls. If your caravan setup involves only these items and you're certain you won't add sensitive electronics later, a modified sine wave unit offers genuine savings.
Are lithium batteries safer than AGM batteries?
Modern lithium iron phosphate (LiFePO4) batteries include Battery Management Systems that monitor cell temperatures, prevent overcharging, and shut down if faults occur. This makes them extremely safe under normal use. AGM batteries lack active monitoring but contain no flammable electrolyte and pose minimal risk. Both technologies are safe when properly installed and maintained; lithium's BMS simply adds an extra layer of automated protection.
Can I mix lithium and AGM batteries in the same system?
Mixing battery chemistries is generally not recommended. Lithium and AGM batteries have different charging profiles, voltage curves, and discharge characteristics. Connecting them in parallel causes the lithium battery to overwork while compensating for the AGM's limitations, potentially damaging both units and reducing overall system efficiency. Choose one technology and build your entire bank around it.