Understanding a 12V Outlets Amp Rating
There seems to be a lot of confusion when it comes to choosing the correct DC to AC power inverter for a vehicle.
I’ve seen a lot of companies recommend getting an inverter that’s 400 watts or less but that advice doesn’t really work for cars or even trucks.
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300 watts is way too much power for the 12 volt plugs in even large trucks and RVs to handle.
The highest amp rating for a 12 volt socket/cigarette lighter is 20 amps, and those are usually only found in large SUVs or heavy duty trucks.
The 12 volt outlets/cigarette lighters in standard cars are usually rated for only 10 or 15 amps.
Why does the amp rating matter? The amp rating tells you how many watts the outlet is capable of outputting.
To calculate the watts you multiply voltage x amps.
Since most cars in the USA use 12 volt power for the electrical system you can usually be sure the voltage will be 12.
Even in larger trucks that might use a 24 volt system, the odds are the cigarette lighter is still using only 12 volt power. If you aren’t certain you can check your vehicle’s owner’s manual.
Here’s the output on watts of the most common 12 volt outlets in cars based on the amp rating.
- 10 amp = 120 watts
- 15 amp = 180 watts
- 20 amp = 240 watts
As you can see the largest inverter for a 12 volt outlet in a normal vehicle is 240 watts. Anything larger will risk blowing the fuse or even damaging the wiring.
So which inverter is right for your car? Below I’ll review 3 of the best DC to AC inverters that use 12 volt plugs.
Before purchasing an inverter make sure the 12 volt outlet you want to use it with is rated to output enough power.
You can also read about how to find out what the amperage of a specific 12 volt outlet is in your vehicle later on in this post.
If you want to use a larger inverter in your car you will need to connect it directly to the battery instead of using the 12 volt outlet.
Last update on 2024-04-23 / Affiliate links / Images from Amazon Product Advertising API
Best Inverters For The 3 Different 12V Outlets in Cars
Ampeak 100W 12V Car Inverter
If you have a small vehicle that only has a 10 amp 12 volt/cigarette lighter outlet this is going to be one of the best options for you.
A 10 amp 12 volt outlet can only supply up to 120 watts of power.
You don’t want to max out the power rating all of the time, so a 100 watt inverter is a safer option.
The Ampeak 100 watt car inverter is around 5.5 inches long, 2.6 inches wide, and 1.3 inches thick.
It’s a convenient size and it won’t be hard to store in the glove box or car door pocket when not in use.
Inside the plug, there’s a built in fuse to help protect the wiring in your vehicle.
The Ampeak offers protection against low and over voltage, overloading, short circuit, and overheating.
There’s also a built in fan to help stop the inverter from overheating.
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On the front, there’s a 2.1 amp USB port and 1 AC outlet.
This is a modified sine wave inverter.
It’s not as efficient as a pure sine wave inverter but it’s still going to be able to run most of the small electronics you would use in a car.
The 12 volt plug can move from a straight to an almost 90 degree position to fit every kind of vehicle comfortably.
The Ampeak 100W 12V Car Inverter is a fantastic option for everyone who wants to run a small AC electronic in their vehicle.
It can be used in the 15 and 20 amp 12 volt outlets as well and if you aren’t sure what the amp rating is you won’t risk going over because no matter what the 12 volt outlet in your car is at least 10 amps.
PROS
- Small
- Works in any 12 volt car outlet
- Inner Fan
- Protections against common electrical problems
- Replacable inner fuse
CONS
- Not a pure sine wave inverter
Common Electronics that Use 100 Watt or less
- Small Laptops/notebooks
- Nintendo Switch
- Most Small TV/DVD combos
- Breast Pumps
Most vehicles have at least one 15 amp cigarette lighter/12 volt outlet. Sometimes it’s located in a harder to find location like inside the center console storage, glove box, or trunk area.
It’s not a guarantee that your car will have one but it’s worth searching for if you aren’t sure.
A 15 amp 12v outlet can output up to 180 watts of power. That means the Energizer 150 watt power inverter will work perfectly.
This powerful little car inverter is a pure sine wave inverter. This type of inverter can be hard to find in anything smaller than 300 watts, so it’s really cool that Energizer makes one.
The main thing that makes pure sine wave better is it’s more compatible with sensitive electronics like printers.
If you’re going to use your car inverter to run a printer this is the inverter you want.
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For laptops and most other electronics, a modified sine wave inverter like the others in this review will be fine.
The 150W Energizer inverter is pretty big but it can still fit in a cup holder.
There’s one AC outlet and two USB QC 3.o ports. One nice thing about the USB ports is they can output up to 30 watts for faster charging.
Since a 15 amp plug is rated for 180 watts you could technically max out the 150 watt AC plug and use the 30 watt USB at the same time and not blow the fuse.
Inside the unit, there’s a fan to keep it from overheating. There’s also a smart chip inside that helps protect against common electrical problems.
The is a fantastic option for both 15 and 20 amp car outlets.
It’s one of the only pure sine wave inverters of this size, so if you’re looking for something that can safely power a printer, this is it.
PROS
- Long power cord
- Inner Fan
- Protections against common electrical problems
- Replacable inner fuse
- Pure Sine Wave Inverter
CONS
- Large Size
- Less budget friendly
Bestek 200W Power Inverter
If you drive a truck, SUV, or semi truck there’s probably at least one 20 amp 12v outlet.
It’s not a guarantee all of the outlets will be 20 amp so make sure you check the manual or fuse panel to make sure the one you want to use is 20 amp.
A 12 volt 20 amp outlet can output up to 24o watts of power. That means a larger 200 watt inverter is going to be compatible.
The Bestek 200 watt inverter is cool because it has 4 USB ports and 3 AC outlets.
You can use the wall outlets for charging laptops and small gaming systems and still have USB ports to charge your phone.
The 200 watt power rating is the max continuous power output. That means you could have one electronic that uses 200 watts of power plugged in or three electronics that use around 60 watts each.
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You won’t be able to plug in 3 electronics that use 200 watts each because that would be 600 watts of power combined.
This uses a modified sine wave inverter. It’s still fine for running most electronics but some printers won’t be compatible with it.
One nice thing about the modified vs a pure inverter is the unit is much smaller and it’s a lot more budget friendly.
Another cool thing about this inverter is it has an on/off switch on it. So you can turn off the inverter without having to unplug it.
Inverters use a small amount of power even if nothing’s plugged into it. That’s why you want to make sure it’s unplugged or turned off when not in use so it doesn’t slowly drain your car battery.
There’s a fuse in the 12 volt plug to help protect your vehicle’s electric system. There’s also a built in fan to help keep the inverter cool.
There’s also a low battery alarm and a feature that will turn off the inverter when the car battery gets too low. There’s also protection against overloading and short circuiting.
The Bestek 200W Power Inverter is an awesome choice for any vehicle with a 20 amp outlet.
You can technically also use it in the smaller 12 volt outlets but it increases the risk of going over the outlet’s power rating and blowing a fuse.
PROS
- Long power cord
- Inner Fan
- Protections against common electrical problems
- Replacable inner fuse
- On/Off Switch
CONS
- Modified Sine Wave Inverter
How Many Amps is My Car’s Cigarette Lighter Rated For?
It’s not always clear how many amps a 12 volt plug is rated for. If there’s a cover for the outlet it will sometimes have the amp information printed on that but a lot of times it won’t tell you any information.
The best way to find out is to look in your vehicle’s manual. In the fuse section, there will be information about every electronic in your car.
The 12 volt plugs should be labeled as a cigarette lighter, cigar lighter, accessory power outlet, or power point.
If your car’s manual uses different terms for the 12 volt outlet and you aren’t sure just know that if the fuse is rated for more than 20 amps it’s probably not talking about the 12 volt outlet.
The picture above shows what amperage the fuses are in my motorhome. It uses a Ford E-350 chassis which is considered a heavy duty truck.
The manual shows that the cigarette lighter (cigar lighter) uses a 20 amp fuse. And the other 3 12 volt outlets (power points) use 20 amp fuses as well.
It’s pretty uncommon for every 12 volt outlet to be 20 amp but because it’s a motorhome the electrical is beefed up.
There are actually only two other 12 volt outlets besides the cigarette lighter, but the manual is for all models of the E-350 and sometimes the accessories in your specific car will vary.
If you don’t have the owner’s manual for your vehicle another way to check the amperage is to look at the actual fuse panel in your car.
Usually, the fuse panel cover will have the fuses labeled and you should be able to find some information about the 12 volt outlets there.
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Frequently Asked Questions
Can I plug an inverter that’s rated for higher power into a weaker power source?
Technically yes. A 300 watt inverter will work in a 120 watt power source but you will still only be able to draw a maximum of 120 watts.
The reason it’s not recommended to do this is the risk of drawing too much power and blowing the fuse is increased.
A larger inverter has a larger fuse in it, so if you go over the power limit of the 12 volt outlet in your car it’s the car fuse that will blow first.
The wiring between the 12 volt plug and fuse panel will be overloaded which could cause some damage.
It’s not unheard of for the wiring behind 12 volt outlets to melt or be damaged when people try and pull too much power.
What’s the difference between a cigarette lighter and a 12 volt outlet in a car?
There’s really no difference, you can use accessories with 12 volt plugs in a cigarette lighter the same way you would use it in a normal 12 volt socket.
The only thing that is slightly different is you can’t plug a cigarette lighter into a regular 12 volt outlet.
Since smoking isn’t as widespread as it used to be most modern cars don’t come with actual cigarette lighters anymore.
But the name has stuck for some reason and most people still call regular 12 volt outlets cigarette lighters, but there’s no difference between the two.
Have any more questions about the best inverters for 12 volt car outlets? Leave a comment below.
Jenny,excellent explanation and information.
thumbs up to you.
You always to such an excellent job of explaining the information in easy to understand terms. Thanks its greatly appreciated.