Auxiliary Car Sockets: How Fast Will They Charge Your Smartphone?

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You may never pay attention to the power outlet or outlets in your car (some cars come with multiple outlets), but they’re important if you’re charging your phone on the go.

You should definitely pay attention to these sockets, because their specifications, as well as the specifications of the adapter and charging cable you use, as well as the charging specifications of your phone, all together determine how well and how quickly your smartphone will charge in the car.

To reiterate, the speed of charging a smartphone in a car depends on three factors: the charging specifications of the phone, the charging specifications of the charger and cable used, and the parameters of the auxiliary power socket in the car.

Once you understand this, you will be able to get the highest smartphone charging speed in your car.

Types of Auxiliary Power Sockets in a Car

There are two types of auxiliary power outlets in cars. In all my years of driving and owning many cars, these are the only two I’ve seen.

Car cigarette lighter sockets: These provide 12V DC and are commonly found in vehicles. They also have a higher amperage, allowing them to deliver more power to the devices they charge.

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USB power ports: They come in a variety of sizes and are designed for 5-volt or 12-volt systems in vehicles. They offer flexibility in charging options. They also provide a much lower amperage than cigarette lighter sockets, so they are much slower at charging devices.

The higher the voltage and current, the higher the power. The higher the watts, the faster the charge. This is a simple rule worth remembering.

How do you know what the power outlets in your vehicle support? You can get detailed information about the voltage, current, and wattage of the auxiliary power outlets in your vehicle by consulting your vehicle’s owner’s manual or checking the labels on the power outlets themselves.

My current vehicle has three auxiliary power outlets – one cigarette lighter socket, one regular 5W USB socket, and one 12V/120W USB socket. Looking at the label on the cigarette lighter socket in my car, it says that the total power when using all the auxiliary power outlets is 120W.

If I only use the car cigarette lighter socket or only the 120W USB port, both can deliver the full 120W. But if I connect multiple devices, the full 120W will be distributed into smaller portions across all connected ports.

How safe are car power outlets for charging smartphones?

Auxiliary power outlets in cars are usually safe for charging smartphones and other devices, including laptops. Be aware that it is possible to overload these outlets.

For example, I have an adapter to charge my laptop on the go. I’ve noticed that it gets quite warm, even hot, when I use it. This is because of the demand the laptop’s power supply puts on the wall outlet.

Sometimes, especially when it’s hot, when I charge my phone in the car, the phone heats up too.

Fortunately, many modern smartphones have built-in protection systems. For example, if my phone starts to overheat while I’m charging it in my car, it notifies me so I can unplug it for a while to cool down.

How fast are car phone chargers?

Modern car phone chargers and auxiliary power outlets support fast charging technology. You might be surprised to learn that there are car phone chargers that support charging up to 75W and even 100W.

For the fastest charge, buy a fast car phone charger that matches your smartphone’s fast charging technology and plug it into your car’s cigarette lighter socket. As I mentioned, car USB ports are rated at 5W, while cigarette lighter sockets are rated at 12V.

If your phone supports 45W charging, you will need a car adapter that supports this power to get the highest possible charging speed.

My current smartphone supports 45W fast charging, while my current car charger only supports 36W, so I don’t get the fastest possible charging speed. But 36W is fast enough; the difference in actual charging time between 36W and 45W is not significant.

Some important things to know about charging your phone from your car’s auxiliary power socket

Charging your phone using your car’s auxiliary power outlet in extreme weather conditions will affect the charging speed and may also damage your device. For example, if you notice your device getting very hot while charging in your car, disconnect it for a while.

It’s also worth noting that GPS navigation apps (like Google Maps) are serious power guzzlers. Your car’s auxiliary power outlets can’t keep up when these power-hungry apps are in use. This means that even if your smartphone is plugged in while you’re using the app, your phone will still be draining battery life. You read that right.

I have experienced this many times on fairly long car journeys. A way to get around this is to turn off the GPS navigation app on a stretch of road that you are familiar with to allow the battery to charge. Only turn on the navigation app when you really need it.

Of course, if you’ll be using GPS a lot when traveling by car, it’s a good idea to make sure your phone’s battery is fully charged before you set off.

Also, if you’re charging your devices in your car while it’s stationary, it’s a good idea to leave the engine running. This is to reduce the risk of your car battery draining. The more charging your devices need, the greater the risk.

Car phone chargers I’ve used

I have used a number of car chargers for my phones over the years. These include ZUS, Sony, IQ and Heatz models. I much prefer to use a dual-port charger in my car so that I can charge two devices at once if necessary. This is important when I have other people in the car with me, especially on long drives. Yes, I am that hospitable. Thank you.

The car’s cigarette lighter socket is my favorite auxiliary socket for charging my phone, and that’s where it’s always plugged in. Using a dual-port car charger, I can get a decent charge for two devices at once.

But the regular 5-watt USB power port in my car is great for charging dumb phones and feature phones because of its lower power ratings. Charging a smartphone through that particular USB port is a painfully slow experience, so it’s not my favorite.

The second USB port has a power of 120W and charges much faster than the car cigarette lighter socket. It is great for charging smartphones with fast charging function.

Of course, USB ports do not require a power adapter. Simply connect a USB cable to charge your phone. The USB-C cable is more efficient for faster charging speeds.

The Nonda ZUS Smart Car Charger has a power of 24 W, so I can relatively quickly charge my smartphone connected to the cigarette lighter socket.

I currently use the Heatz dual-port car charger. It supports Qualcomm Quick Charge 3.0 and a combined output of 36W over two ports. It gives me really decent smartphone charging times when I’m on the road.