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How long will a deep cycle battery run a TV?

Running a Television with a deep cycle battery is nothing new but it’s definitely a fun subject. Let’s assume that you want to run your television in the deep woods while camping and you’ve got an AGM battery with you. How long would a deep cycle battery run a TV?

Well, assuming you’ve an AMG 12 volt deep cycle battery rated for 100 ampere hours and a power inverter you could power a 150 watt TV for about 6.1 hours. A smaller 20 watt TV would get a lot more mileage, with a running time of about 56 hours.

Camping just got a lot more fun! There is a bit of math involved when it comes to calculating how long you can run a television with a deep cycle battery.

Today we’ll go into the variables that you need to know and introduce you to ‘Peukert’s formula’ so that you can calculate on your own exactly how long your battery will power televisions.

Let’s start with your Television.


First we’ll need to determine the watts used by the television

There are many different types of televisions and they all have very specific power requirements. Some, like LED televisions, are extremely energy-efficient, while other televisions, such as Plasma are not. If your TV is an LED of LCD television, then their watt usage is generally going to be something like this:

  • Small (15 – 20 inch screen) – Approximately 15 – 26 watts
  • Medium(21 – 32 inch screen)  – Approximately 26 – 70 watts
  • Large (32 – 55 inch screen) – 55 – Approximately 150 watts

Now, if these are not LED or LCD televisions that you are looking to power then we can get quite a bit of variance. Plasmas are the highest, ranging from 150 – 300 watts, while older CRT models might range around 65 – 120 watts for up to a 24 inch screen.

If you aren’t sure (or if you’d just like an excuse to get a useful new tool) then we recommend acquiring a Power Monitor. These let you find out exactly what power is being used for a specific device and they really come in handy.

This can get you an exact watt reading if you aren’t able to acquire it online or through the manufacturer.


What is the amp rating of your deep cycle battery?

Next you are going to need to how many amps your deep cycle battery is rated for. Known as ‘Amp Hours’, when you see on your battery a number, generally 55 – 100 with ‘AH’ next to it then this is your ‘Amp Hours’ rating.

Depending on how many amps are needed, you can get a good idea of how long the battery would last.

Deep cycle batteries are designed for long-running, so they are usually rated at a 20 hour rate. A 100 AH AMG would be able to provide 1 amp per hour for 100 hours or 5 amps per hour for 20 hours.

A higher draw can also affect this and we’ll talk a little more about that shortly, for now just make a note of your amp hours underneath where you’ve written your TV watt requirements.

Would a Generator be better? Read here!

You will also want a pure sine wave inverter

While your 12 volt deep cycle can power all kinds of things, when it comes to your electronics you want to be as nice as possible where power is concerned. After all, we don’t the device to be damaged just for one very interesting evening of camping entertainment.

A pure sine wave inverter will help to minimize anomalies when you are powering your TV so that we can minimize your chances of damaging it.

Select a pure sine wave inverted that is rated for 800 peak watts and you should be able to power your Television and a few other small devices in the bargain. Now we just need to get down to the math.

Calculated your exact run time

We’ll give you this formula but we highly suggest that you Google ‘Peukert’s Formula’ and ‘Peukert’s Law’ if you really want to get the whole scoop on this methodology. The equation for determining how long that battery will last looks like this:

T = C / In (or C = T * In)

Yikes! We can break that down a little, however, to make it more digestible. Here are the variables:

  • C – Capacity at 1 amp; 20 is for a deep cycle battery
  • T – This is just short for ‘Time’
  • I – Amps used
  • n – Peukert number/constant, which will be 1.1 for an AGM battery

That turns our equation of T = C / In (or C = T * In) into this:

Time the battery will run = 20 ((Amp Hours  / (Amps Drawn * 20))^1.1).

This is why a little Googling is recommended, as the math can be a little tricky until you’ve done this a few times. A quick sampling of results might be more useful for our purposes, like this:

  • A 55 AH AGM could power a 20 watt television for about 29 hours or a 150 watt for about 3.16 hours.
  • A 100 AH AGM could power a 20 watt TV for about 43.8 hours while a 150 watt would run for about 4.8 hours.
  • A 65 AH Flooded Lead Acid deep cycle battery could run a 20 watt TV for about 36.7 hours and a 150 watt for about 3.3 hours

Some final advice on running a TV with a deep cycle battery

Be sure to go with that pure sine wave inverter if you decide to try this little experiment on your next camping trip to help to ensure that your electronics are safe.

Your deep cycle battery can certainly run your TV so if you are looking for a way to spice up your time in nature, we hope that we have given you a novel idea today.

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All the article on Oofgrid offer help and practical advice for using and purchasing a portable generator. However, We are enthusiasts and not qualified electricians. Always seek professional advice when working with electrical or Petrol appliances.