How Long Can A Car Battery Power a TV? (Deep Cycle Battery)


How Long Can A Car Battery Power a TV

Have you ever wondered how long a car battery can power a TV?

Whether you are camping off-the-grid, Overlanding, or just have plain old lost power due to bad weather, it can be useful or important to stay informed or you may just want to have some entertainment.

Just as these two needs you would most likely satisfy at home by turning on your TV set, you can also do so in these other settings.

To do so you certainly have the most important thing you would need, a power source, in the form of a car battery.

With a power inverter, you are all set.

So, how long a car battery can power a TV? On average a standard car battery will be able to power a TV for around 10 to 20 hours. However, to avoid drastically reducing the life of your battery, do not run a TV for more than 30 hours on a 41-amp-hour car battery before recharging it with a car engine, generator, or solar panel.

How Many Watt-Hours In a Car Battery

A car battery has the major role of providing a massive current for a few seconds to turn over the engine. However, a battery might be able to provide 500 Amp of current at a voltage of 8 to 10 volts during this starting phase.

A Standard car battery has 60 AH capacity and 12 Volt so its power capacity is around 720 Watt – hours.

How Long Can A Car Battery Power A TV?

The short answer is that it depends on two things, how much power your TV set draws and what is the capacity of your car battery.

To quickly find out the maximum how long you should expect a car battery to power your TV set, all you need to do is to divide the battery’s ampere-hours (Ah) capacity with TV sets amp draw.

For example, if your battery has a 41Ah capacity and your TV set draws 0.5 amps, it will give you a maximum of 82 hours running time.

But, that is not a full picture. All power inverters have some percentage inefficiency and power loss when converting 12 volts direct current to 120 volts alternating current. On average, it is around 15% of energy loss.

So in the above example, you can expect your TV to run for around 69.7 hours of running time, with everything else being equal.

But in real life, nothing is actually equal to laboratory testing, and actually running time of the TV set of your car battery will be closer to 60 hours.

The reason is the combination of car battery capacity and inverter’s minimum acceptable voltage.

The table below shows how many hours you need to power a TV with a car battery:

Screen Size (Inches)Power LED – TV (Hours)Power Plasma TV (Hours)
30205
32184,5
37164
40143,6
42123,3
50102,4
5591,9
6081,4

How Long Will a Car Battery (12v) Power a TV? >> Check out the video below:

Car Battery Capacity

Typical car batteries are made of 6 cells, with each providing 2.1 volts at the full load, in other words, when fully charged a car battery will provide 12.6 volts.

When any battery is at its 0% capacity, it means that it has reached its shutoff point. For car batteries, it is usually at 10.5 volts.

Ampere-hour rating or capacity of a car battery is the current it can continuously provide over 20 hours period and at an environmental temperature of 80 degrees Fahrenheit.

So for example, a 41Ah battery will provide 2.05 amps of current over 20 hours period before reaching the shutoff point.

In case that the current draw is lower, the running time will go up, and vice versa.

You can run a TV off a deep cycle battery for around 20 hours

Read also: How Many Watt Solar Panel To Charge Deep Cycle Battery? (Explained)

Power Inverter Minimum Input Voltage

Power Inverter’s minimum input voltage, or start-up voltage, is the minimum at which it can operate. In case that the provided voltage is below this number, it just will not output any current.

In most cases, this is 10.7 volts, which is the reason why your power inverter very likely will not be able to drain 100% of car battery capacity.

TV Set Current Draw

How many amps a TV set draws depends on many factors, but most directly correlating is the size of the screen and technology it was made with.

Determining how much current your TV draws can be done by calculating from its wattage. All you need is to divide it by 120 volts.

The potential problem with this calculation is that printed on the backside of your TV you will most likely find the maximum power draw.

Which is a rating with the brightness and volume cranked all the way to maximum. A more precise method is to actually measure it with some watts meter such as a Kill A Watt.

And you shouldn’t be surprised to see a measurement that is several times below the power rating.

By measuring the actual wattage of your TV set during normal usage, you can see how large of an impact it can have to decrease the brightness of your screen.

The difference between 50% and 100% brightness can be as much as 45%, which in turn translates into up to 90% longer running time from a car battery.

Should I Discharge Car Battery To Inverter’s Start-up Voltage?

One thing you must keep in mind is that car batteries are not deep discharge type. In other words, they are not intended to be often discharged close to their 0% capacity.

For all rechargeable batteries, and car batteries are such, applies the rule that they have a limited number of recharging cycles they can withstand before they become unable to be recharged again. In other words, before they die.

For many types of batteries, there is a relation between how many percent of their capacity you discharge with how many times you can recharge them.

One charging cycle is defined as discharging overall 100% of their capacity and then recharging them back to 100%.

This means in practice that if a battery has a lifespan of 1.000 charging cycles if you always fully discharge them, you can recharge it 1.000 times before it dies.

But, if you always discharge it to 50% you can recharge it 2.000 times.

This relation doesn’t apply to car batteries in exactly this way. The reason is in their physical construction and chemistry of operation.

Read also: How Long It Will Take To Charge 12v Battery With Solar Panel? (Explained)

The lead plates used in them are relatively thin, and while they are able to produce high bursts of high currents, they are not very resilient to the other extreme mode of operation, providing low currents for extended periods of time.

Every time a car battery is discharged lower than 50%, its number of the maximum potential charging cycles decreases.

So, to keep its lifespan in some expected range, and avoid its premature death, you should avoid discharging it below 50% of its capacity or in other words, under 11.55 volts.

How Long Should I Power A TV With A Car Battery?

When all the limitations and other factors, such as the real power draw of your TV are taken into account, a TV set that draws 0.5 amps shouldn’t be kept longer than 30 hours on a 41 amp-hours car battery before that battery is recharged with a car engine, generator, or solar panels.

That way the lifespan of the battery will be lowered only by some reasonable amount.

The best practice is to actually go even easier on your car battery and avoid powering such small consumers like a TV set is for longer than 5 hours continuously.

And to instead use the deep discharge batteries that are more suitable for such use.

Whether you are planning to go off-the-grid, or in a case of a power outage, you may have a need to keep your TV set running, either to get informed or entertained. But in such a scenario, you will need a power source of some type.

The car battery that is sitting in your vehicle in a driveway or garage is one of the potential solutions.

In combination with a power inverter, it can very comfortably power your TV for at least a while. Depending on the capacity of the car battery and power draw of your TV, it will vary for how much exactly.

How long Do LED Lights Last On Batteries

On average typical LED lights will last around 11 years on batteries when used 12 hours a day. This is 25 times longer than a typical halogen lamp.

Use Car Battery to Power Appliances

Running electronics off a car battery. The table below shows what can you run on a car battery:

Domestic appliancesAmps UsedWatts UsedRunning Hours
Electric blanket<0.56012
Fridge0.651505
Freezer0.862003,6
Mini Fridge<0.51008
Fridge Freezer1.53502
Kettle1330000,24
Satellite TV box<0.53024
Printer<0.55015
Radio<0.54018
Radiator8.520000,36
Desk lamp (with 60 W lamp)<0.56012
DVD player<0.52825
Hair dryer10.022000,3
Hair straighteners<0.560 – 10012
Landline cordless telephone charger<0.51072
Computer monitor<0.51008
Desktop computer3.07001,5
Television 42″ HD0.51206
Games console0.86<2004

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Mike Gilmour

Hi, I'm Mike, co-founder, and editor of RV and Playa. My passion is traveling (with my RV) and enjoying the day at the beach (Playa)! Well, I originally created this blog as a way to share what I've learned by experimenting with the RV lifestyle, and I want to help others develop in life through new skills and opportunities.

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