Maybe you’re heading out on a weekend camping trip and want to run a small TV or maybe the power is out and you really want to keep your TV up and running to catch the weather reports.
Without conventional power from the outlet at your house, you’re going to have to get creative.
You’ve got access to a 12-volt battery in your car… hmmm…
A car battery can power a 30-watt TV for about 10 hours until the battery is 50% discharged.
However, the answer has many variables. I’m going to cover to what extent a car battery can power a TV, the best battery option to do the job, and the ideal TV to use for maximum longevity of use.
Here’s a quick table below if you know the size of your particular car battery (using either RC, AH, or CCA ratings), and the actual wattage being drawn from your TV. To determine that, use a Kill a Watt meter like this one seen on Amazon. I’ve found TV’s to run at about 1/5-1/4 of their rated watts seen on their sticker.
How Long Can a Car Battery Power a TV?
|Car Battery: 200-315 CCA; 40-60 RC; 36-46.2 AH||Car Battery: 315-550 CCA; 60-85 RC; 46.2-58.8 AH||Car Battery: 550-1,000 CCA; 80-190 RC; 58.8-111 AH|
|20-Watt TV||9 - 9.5 Hours||9.5 - 15 Hours||15 - 28 Hours|
|30-Watt TV||6 - 6.25 Hours||6.25 - 10 Hours||10 - 18.5 Hours|
|40-Watt TV||4.5 - 4.75 Hours||4.75 - 7.5 Hours||7.5 - 14 Hours|
|50-Watt TV||3.25 - 3.5 Hours||3.5 - 6 Hours||6 - 11 Hours|
Can a 12-Volt Car Battery Be Used to Power a TV?
A 12-volt car battery can be used with a power inverter to power a TV. However, since a car battery is a starter battery, it will be damaged by deep discharges for powering electronics.
In many instances when were are looking at the “ability” for a car battery to power a TV for even a short time, the answer is YES. Yes, it can power the TV. The next question becomes: should I be powering my TV from my car battery?
In most cases of “should it” power a TV, the answer is NO. If you’re going to be powering anything larger than a portable TV/DVD player, you’re going to want to have another method if at all possible.
Cars have a starter battery, known as an SLI (Starting, Lighting, and Ignition). They are designed to release a high amount of current for a few seconds to start up all of the systems in your car and then be charged back up by the car’s alternator at a fast rate immediately afterward and stay topped off.
They do not have the internal design or chemistry to repeatedly power something over a long duration of time for a deep draw of power.
Let’s Go Over an Example
Let’s take look at an example (for basic understanding purposes, not considering the inefficiencies, internal resistance of the battery, etc.):
1st: The Battery
- I’ve got EverStart Plus Group 96r battery in my vehicle. I cannot locate the Reserve Capacity (RC) anywhere, even online. I’m going to assume that they are keeping up with the industry standard for batteries of that size, so that would be 90-95 minutes. I’ll go with 90 for this example.
- Reserve capacity is simply how many minutes the car will function if the alternator were to die and the battery was not charging while the car was running. It assumes the draw from the car will be 25 amps.
- Amps x Volts = Watts
- I like to get everything to Watts in my calculations. You can certainly do it with Amps and it isn’t any harder but this way I always do it.
- (90 RC Battery Minutes × 25 amps) ÷ 60 minutes = 37.5 amp hours (on a high amp draw of 25 amps)
- 37.5AH/0.75 = 50AH — I’ve noticed a strong pattern of dividing the reserve capacity result by 0.75 to achieve a “close to actual” AH based on the standard 20-hour rating. (Explained in the embedded video).
- 50 amp hours x 12-volt battery = 600-watt hours
2nd: The TV’s
- I have a 32” flat screen LED TV in my bedroom and the sticker on the back reads 120v @ 1.3a. In actuality, instead of running at 1.3 (or 156 watts), I’ve tested it with a relatively inexpensive “Kill a Watt” (seen here on Amazon) and it only runs at 1/5 that amount! (about 30 watts or when all is said and done.)
- I also have a 7” portable TV/DVD in the car that my daughter watches. The sticker reads 12v @ 1amp. (It might actually be less, like the one above but I haven’t tested it).
- 12v x 1amp = 12 watts
3rd: When Combined
Keep in mind that a car battery is damaged if it is discharged more than 30%, even more at 50% and even more when fully discharged. It will probably only survive a full discharge one dozen times or less. If you drain it more than 60% it probably will not start the car. Let’s only do 50% to make sure we won’t be stuck needing a jump!
With that being said, let’s take the 600-watt-hours for the battery and multiply it by .5 to see how much energy we have to work with at 50% use. 600 × .5 = 300-watt-hours to work with.
- 32” Standard LED TV: 300 battery watt-hours ÷ 35 TV watts needed = 1.44 hours. (I divided the 30-watts from the TV by 0.85 to factor in the inefficiency of the power inverter which is generally 15%. 35-watts needs to be drawn from the battery to overcome the 15% loss of the inverter and still supply the TV with 30 amps.
- 7” 12v TV: 300 battery watt-hours ÷ 12 watts = 25 hours. Since the 12 watts from the TV is well under 10% of the total 450-watt-hours available from the battery (only 2.66%!), and you won’t need an inverter, then you’ll likely keep this number close to what the math says.
What type of TV is Best to Power with a Car Battery?
Taking the lesson that we just learned, the size and type (LED, LCD, Plasma, etc) of the TV will be the primary variables.
The small, direct current TV/DVD players are great if you want to have screen time for a long duration using just your car battery. In a power outage, you could bring your battery inside, hook up a DC socket to it with alligator clips, and plug the TV right in.
Some of these small portable TV’s have the DTV feature which allows you to watch free-to-air digital broadcasts without hooking up any additional antennas. For other TV’s without a built-in antenna, you could always check out antennas like this on Amazon. There are plenty of models out there to fit your needs.
If you’re looking for a stationary TV to use at home during a power outage, you’re going to want to want to find something far more efficient than one that runs on alternating current (AC) so that you can maximize the potential energy from your car’s direct current (DC) battery.
A TV like this one seen on Amazon fits the bill and comes in sizes from 13″ up to 24″. They would be a great addition to that spare bedroom since they are also AC compatible, and when the power goes out you can easily switch it out to be the primary TV to run off your battery bank or car battery.
For example, the 15.6″ one from Amazon draws 2 amps at 12 volts which is 24 watts. That would get you 12.5 hours of usage from the car battery example above!
The 22” TV draws a total of 36 watts, which would get you 8.3 hours of use from a car battery!
These are definitely worth looking into as a backup TV if you are concerned about a power outage or even for traveling in an RV!
What Type of Battery is Best to Use to Power a TV?
Anything that is “Deep Cycle” is going to be better than your car’s starter battery far and away! The technology in a deep-cycle battery (Marine, Golf Cart, AGM, Gel Cell) is specifically designed to give out a low output for a long period of time. A high-efficiency 12v TV would be perfect for these.
I personally have an adequate 12v home battery power backup system made from 2 golf cart batteries and has an Amp Hour rating of 215. That means I could run my 32″ LED TV for 37 hours without worrying about recharging (that’s only running my system down 50% but it could well go down to zero if I needed it to for double the time).
As far as how many dollars per Amp Hour are concerned, you can check out my blog post here for an in-depth but easy to understand breakdown. The golf cart batteries win, but the overall upfront cost is higher since you’ll need to buy two.
If you’re just looking to run the TV and not much else, you could easily get away with a marine deep cycle battery (not a starter, not a starter/deep-cycle hybrid — just the deep-cycle option). For about $100-$120 you could find one with a 100 Amp Hour rating. That would let you power a 32″ LED TV for 35 hours on a full cycle, or over 17 hours if you were to only run the battery down halfway.
Running the 32” LED TV from my example above at 35 watts, you would get over 34 hours of use on a full cycle (or 17 hours off of a half cycle). Remember, this is only taking the TV into consideration and not a gaming console, modem and router, or cable setup.
- 100AH marine battery × 12 volts = 1,200 watt-hours ⟹ 1,200 battery watt-hours / 35 TV watts = 34.3 hours (fully discharged battery)
What’s great about a deep cycle is that they are way more forgiving when you drain the battery down and recharge it. Car batteries are killed quickly by using them for low-draw, long-duration use. Deep-cycles are designed for it!
The car battery will die after a dozen or so full discharge cycles, but a marine battery will get you 150-175 full discharges or more!
Having a marine battery on hand is also a great step in basic preparedness when it comes to simply rigging up some lights and charging your devices around the house when the power goes out. Just make sure to keep it properly charged and maintained in the meantime and it should take care of you for many years.
How to Get More TV Time Out of Your Car Battery
So far, I’ve covered what a car battery can do by itself when it comes to powering a TV and the capacity of that car battery has been quite limited when compared to other options.
However, this all changes if you run the TV with a DC/AC power inverter that is hooked up to your car battery while the car is running. In that case, you now have a small portable generator and as long as the car is running (and using gas), you can get away with powering most standard size TV’s in the home.
The limitations of this are primarily the weather, theft, and how much gas is in your tank. Your exhaust has to be pumped outside so at least half of the car has to be out of the garage. The power inverter is an electronic and gets sad like most electronics when it gets wet. It will also be unattended while this is happening and your car will be unattended with the keys in it.
Just a few things to consider there, but it might be a completely viable option for you!
Can you run a TV off of a car battery? Absolutely! Should you (if you care about the health of your car battery)? Absolutely not, unless it is a low wattage LED TV or a 12v DC TV.
Honestly, if you’re looking for a cheap solution for running your during a power outage or when camping, I’d recommend either getting an inverter and running your car while powering your TV, or simply investing in an inexpensive inverter generator. They are wonderful companions for minor power outages, safely run electronics without a hiccup, and are extremely quiet by generator standards.
This 2000-watt Inverter Generator from Amazon is an excellent option for your first inverter generator and will very likely be able to power your fridge as well!
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