Wanna know why USB port your car does not charge your telephone ? You are not alone. It happens constantly, and this is one of the most common questions we get.

If your car USB port does not charge your phone, the problem may be with the port, cable, or even the phone. Not all car USB ports are designed to charge phones or power peripherals, so chances are you’ll run into this situation.

An illustration of two scenes showing 17% phone charge and 9% phone charge in the car.
Lifewire / Tim Liedtke

There is also the possibility of a compatibility issue between the port and the phone, which may or may not be resolved with a different cable.

Strengths and weaknesses of charging USB phones in cars

USB is great because it’s the standard that almost everyone has chosen, so you can use the same cables to connect a whole host of different things. The problem is that while USB is capable of transferring both power and data over the same connection, not every USB port is wired for it. And even if USB port designed to provide power, slight interference in the way some companies such as Apple manage USB charging can interfere.

When USB first appeared, the original standard allowed for two different versions of USB ports: data ports and powered data ports. USB data ports only transfer data back and forth between the device and the computer, while powered data ports transfer both data and power. That’s why some devices like hard drives and scanners, that are powered by a USB connection must be connected to specific USB ports in order to work.

USB data connections in cars

On some vehicles with a USB port, the port is for data transfer only. This type of USB port usually allows connect USB flash drive to listen to music or installing firmware updates, or you can connect your smartphone or MP3 player to listen to music. Because this type of port only uses data terminals and not power terminals, it cannot power any peripherals or charge your phone.

If you’re not sure if your car has a data-only USB port and your owner’s manual doesn’t say anything, there are several ways to check. The easiest way is to try different USB cables and devices to see if they have any kind of power connection.

USB data cables and charging cables

The USB standard specifies the configuration of four terminals, numbered one through four. Terminals 1 and 4 transmit power and 2 and 3 transmit data. Most USB cables are simply direct connections between the terminals on one end of the cable and the terminals on the other end, allowing the cable to carry both data and power.

Data-only cables skip terminals 1 and 4 completely, and power-only cables skip terminals 2 and 3. However, the situation is actually a bit more complicated than that. In order for computers or some infotainment systems to provide higher charging power, simply plugging in the charge-only cable will not help. The computer needs to receive a certain cue that tells it to provide higher amperage, and this cue differs depending on the device in question.

The USB specification requires charge-only cables to have data wires or terminals two and three shorted at the end of the device. So to turn the ordinary USB cable in cable for charging, terminals two and three at the end of the device cable may be shorted. This works for most devices, but Apple products work differently.

USB ports in cars

While a car may have a power-only port, most USB ports in cars are still connected to the infotainment system. So even if the vehicle includes a powered port, the main use of the port will still be for data transfer. The problem is that in some cases you can connect your phone and infotainment system will not be able to recognize what type of device it refers to. If this happens, it may not charge your phone, even if the port is actually capable of doing so.

Sometimes you can get around this problem by using a USB cable specifically designed for charging. This type of USB cable is completely incapable of transferring data, so you won’t be able to use it to transfer files or listen to music. However, the fact that the infotainment system can’t tell that a device is connected means your phone will still draw power from the port.

Another issue with powered USB ports and chargers like phones is that different companies approach USB charging differently. The problem is that although all USB ports are rated for 5V, they are capable of delivering different amounts of current, and different phones require different amounts of current to charge. For example, some phones will charge normally at 1.5A, while others will charge very slowly or even use more power than the USB charger can supply.

If your car recognizes your phone and connects it in media player mode using a regular USB cable, there is a chance that the applied charging current will not be high enough to keep your phone charged. Either way, you can try using a charging cable designed to work with your particular phone, which might help. If it doesn’t, you’re probably stuck with USB cigarette lighter adapter .

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