Welcome to the electrifying world of current and voltage.
Puns aside, if you’re a serious caravanner, you’ll be intimately familiar with your caravan’s batteries, what they can power, and how long they can provide power before going flat.
You need to factor in everything—your TV, lighting, heating and cooling, microwave, sound system, chargers, and more.
So if you’re buying a 12V TV, you need to know how much power it draws to ensure that you can use it without risk of your battery going flat far from home.
So how do you calculate this?
To understand this, we need to know a bit about battery anatomy and power draw.
Just want to skip to the calculator? Click here.
Battery Capacity
Capacity is measured in ampere-hours (Ah) and is an indication of how much power your battery can store. This number can vary, but the larger the capacity, the more power it can deliver for a longer time.
For example, a 100Ah battery can deliver:
- 1 Amp for 100 hours
- 10 Amps for 10 hours
- 50 Amps for 2 hours
- 100 Amps for 1 hour
Voltage
Voltage is a measure of how much force is used to push electricity around a circuit. Think of it like water pressure in a hose: the higher the voltage, the more ‘pressure’ is used to push electricity through a circuit.
Lower voltages such as those found in 1.5V AA batteries have low pressure, making them useful for smaller devices such as remote control and toys.
High voltages such as the 240V circuits found in your home are required to run big appliances such as your oven or heating.
12V batteries provide enough ‘pressure’ to power lights and small appliances such as your 12V TV.
The voltage will be written on your battery.
Power Draw
Power draw (or power consumption) is how much electricity a device uses, usually measured in Watts (W). Sometimes, it's also listed in Amps (A).
Calculating Run Time From Battery Capacity and Power Draw
So we can assume the voltage of your 12 Volt Caravan battery is 12V (shock).
Your battery capacity will vary, but will probably be around the 100Ah mark.
You’ll find your TVs power draw in the manual, but let’s use 25 Watts for an example.
Now we know the battery voltage, capacity, and the power draw of your 12V TV, we can use the following formula to calculate how long your battery can power the TV.
Duration (Hours) = (Battery Capacity in Ah x Battery Voltage in Volts) ÷ TV’s Power Draw in Watts.
For example:
Battery Capacity: 100Ah
Voltage: 12V
TV Power Draw: 25W
Run Time = (100Ah × 12V) ÷ 25W
Run Time = 48 hours
So, with a 12V battery with a capacity of 100Ah and a 12V television drawing 25W of power, you’ll be able to run the TV for 48 hours before your battery dies.
Battery Runtime Calculator
If maths isn’t your thing but you need to know the power draw of your 12V TV, you can simply use our calculator below.
You’ll need to know:
- Your battery’s capacity in Ampere Hours (Ah)
- Your TV’s power draw in Watts (W).
Don’t have your TV’s power draw in Watts but in Amps instead?
That’s even easier. Simply divide your battery capacity by the Ampere draw of your TV. Here’s an example.
Battery Capacity: 100Ah
TV Power Draw: 1.8A
Duration = 100 / 1.8A = 55 Hours
Is It This Simple?
For the most part, but we need to talk about efficiency and energy loss.
No battery system is 100% efficient - some power is always lost as heat or through resistance in wires and connections. Over time, battery capacity also degrades. This means your actual run time may be slightly lower than the calculation suggests.
This might be in heat, noise, or something else, but always remember that while your TV should theoretically run for the times indicated in the calculator above, you will lose energy somewhere that reduces your overall runtime.
If you know you’ll be away from a power source for an extended period of time (such as a house or campsite) you should always err on the side of caution and restrict your power use.
Make sure you’re aware of how much power all your devices draw, and always unplug anything that isn’t being actively used.
What Impacts How Much Power A 12V TV Requires?
12V TVs all draw different amounts of power. Generally, a TV will require more power if it does more.
For example, the following features in a 12V TV draw more power:
- A larger screen;
- Larger speakers;
- USB ports to charge devices;
- A higher definition screen;
- Connectivity to other devices (i.e. Bluetooth, Wi-Fi, Chromecast);
Basically, the more your TV does and the more devices you have connected to it, the more power it draws.
Understanding your battery’s capacity and power consumption helps you plan better and avoid running out of power when you need it most. If you’re unsure about your ENGLAON TV’s power draw, contact us at service@englaon.com.au - we’re happy to help.
