4 August 2025

The Ultimate Camping Power Guide: Thinking in Watts, Not Just Volts

Confused about portable power storage for your camping applications? When planning your off-grid power system, it’s easy to get bogged down. Why not go with the flow and think in Watts?

Enjoying comfort off-grid is now easier than ever before, with fixed and portable campsite power rapidly evolving. Trouble is, many off-grid power storage solutions, especially modern lithium camping batteries or Portable Power Packs, are rated at various Amp-Hour and Voltage combinations, creating confusion when comparing different systems.

That’s why we’re flipping the sums to uncover what we use and what we need.

So, Why All the Different Voltages?

Manufacturers tailor lithium battery Voltage for specific needs. Lithium camping batteries consist of 3.2V or 3.6V cells, depending on the chemistry (i.e., Li-ion or LiFePO4, popular in Australia). These are bundled together to create packs for different jobs. Batteries rated between 12.8V−14.4V are often for cars and compatible caravan setups. Some 18V−32V batteries are optimised for power tools, while other batteries, battery banks or Portable Power Packs optimise Voltage for longevity and charging capabilities, which can vary according to the size of the system.

Let’s Talk Watts

Electrically speaking, the power your appliances use at any given time is measured in Watts (W). Think of it as the rate of flow, calculated as a product of Voltage and Amps. Watt-Hours (Wh) represent that usage consumed for an hour. So, if a device uses 20 Watts for an hour, it has used 20Wh.

Watts and Watt-Hours are brilliant for comparing different types of power systems because a battery’s Watt-Hour capacity dictates your total available power. It’s the common ground. Solar panel output is also measured in Watts, and an appliance’s maximum Continuous Watt usage is usually easy to find or calculate.

Thinking in Watts

In theory, to calculate an appliance’s Continuous Wattage multiply its Voltage (V) by the Amps (A) it draws.

Formula: Voltage(V)×Amps(A)=Watts(W)
Example: A 12V fan that uses a maximum of 0.35A on its highest setting (12×0.35) will use up to 4.2W continuously.

To figure out your battery’s total storage in Watt-Hours, you multiply its Voltage (V) by its Amp-Hours (Ah).

Formula: Voltage(V)×Amp−Hours(Ah)=Watt−Hours(Wh)
Example: A 43.2V, 23.2Ah lithium battery stores 1002Wh. In theory, that lets you use 1002W for an hour–or 501W over two hours, or 250.5W over four hours, and so on. Large battery banks store multiple Kilowatt-Hours (kWh), each equalling 1000Wh.

Now, this is a great start when matching usage to a compatible system. However, a battery’s chemistry and other power system variables reduce the usable power available which we’ll explain soon. But first, let’s chat voltage.

Voltage and its impact on 12V & 240V Outlets and Gear

Voltage is all about power potential. A 10A 240V domestic outlet, for example, can deliver 2400W compared to 180W for a 12V 15Ah merit plug in your car or RV. Some appliances use more wattage than others; electric heating and cooking require lots of power due to the heating element, which is why toasters, electric kettles, heaters and hair dryers are usually 240V.

How Pure Sine Wave Inverters help

Not all 240V appliances use more wattage than their 12V cousins. But you still need to convert the power source to 240V to plug them in off-grid–which is where pure sine wave inverters fit in.
Inverters are rated by their maximum Continuous Wattage, which can be as low as 150W (less than that merit plug) or up to 5000W. As they’re rated for Continuous Wattage, pure sine wave inverters allow for split-second spikes in Wattage that occur when switching on appliances.

Pure sine-wave inverters maybe included as part of a Generator, Portable Power Pack or a separate device installed in your caravan or tow vehicle.

Where’d My Power Go?

So you’ve crunched the numbers but you’re not getting enough power from your portable or fixed power system? Here are common factors that influence the usable power you get–whether it’s a battery box, fuel generator, solar generator or complete retrofitted RV power system.

Common factors include:

Inverter Efficiency: Inverters have a ‘conversion rate’, typically around 90 per cent but can be as low as 80. They use power just to run themselves.
Battery Chemistry: Lithium batteries typically have an 80 per cent usable capacity to protect the cells. For AGM batteries, this is only about 50 per cent.
Charging Voltage: Voltage is vital when you’re charging. A 12V AGM battery, for example, requires around 14.7V to charge fully, which is why DC-DC chargers exist.
Generator Ratings: Fuel generators across the board don’t advertise their continuous wattage loudly. This figure is usually published deeper in the specifications.
The Weather: Cloud cover, shade, and panel angle heavily influence solar panel performance.
System Resistance: Every system has it. The heat caused by wires that are too thin or from poor connections, for example, dramatically reduces a system’s efficiency. AS/NZS 3001.2 explains how to minimise this.