What to do if the USB charging in the car is too slow?

[LeEleanor]

Not being able to quickly charge your phone is because the interface on the car CD player is for data transfer, not charging, and its output is only 500mA. Note that the current output of the car charger should not be less than the maximum rated input power of the phone; not only will it be slow, but it will also get severely hot, and prolonged use can damage the phone's battery.

[DelNadia]

I've also encountered slow charging issues in my car and later figured out a few solutions. First, check the data cable—original factory cables might have poor transmission efficiency. Switching to a short cable that supports fast charging can significantly speed things up. Second, look at the USB port's power output. Most built-in car ports only provide 5V/0.5A, which naturally results in slow charging for phones. You can buy a cigarette lighter adapter with QC3.0 or PD fast-charging protocols, which can output over 18W. This way, you won’t lose battery even while using navigation. Sometimes, the car’s infotainment system may limit output power, so it’s advisable to close background apps to reduce the load. Recently, new gallium nitride (GaN) car chargers have emerged—they’re compact, dissipate heat well, and are worth trying. If none of these work, it might be necessary to check if there’s a poor connection in the car’s circuit.

[DelAlessandra]

Slow car charging is a common issue, mainly due to current limitations. Most vehicle USB ports follow older standards, capping power at a mere 7.5W. I always carry a multi-function fast charger that plugs into the cigarette lighter, delivering 45W—enough for tablets and laptops. Cable quality matters too; after unpacking and comparing two data cables, the difference in copper core thickness was striking. Owners who've modified their center consoles might consider installing a dedicated charging module, which can double the power output. A friend recently installed a wireless charging pad in their car, offering 15W—far more practical than the factory USB. Remember to turn off your phone's 5G and GPS while charging to reduce power loss by 30%.

[BriellaLynn]

I've researched solutions to this issue. The original USB port in the car is primarily designed for data transfer with USB drives and has weak power output capability. A simple and effective solution is to purchase a high-current car charger - a PD fast charger costing just tens of yuan can achieve 20% charge in 20 minutes. When selecting, pay attention to the output specifications and choose models with 9V/2A or higher. The charging cable is equally important, using original or MFi certified cables yields better efficiency. Charging speed may also decrease due to overheating in summer, adding a phone holder near the air vent can assist with cooling. Some newer models have high-power Type-C ports reserved under the center console - checking the manual might reveal a pleasant surprise.

[DiCassandra]

As a seasoned driver, here's a practical tip: First, rule out hardware issues. Borrow a friend's charger of the same model to test – if the speed is normal, then it's a device problem. Clean the charging port with a toothpick to remove dust for better contact. I recommend using a car charger with voltage display, like the Xiaomi car charger I use, which can monitor output power in real time. Slow charging while driving is normal as the vehicle's electrical system prioritizes the engine. Charging efficiency can improve by about 40% when parked at idle. For modifications, some car enthusiasts with electrical knowledge directly tap power from the fuse box to install dual USB modules supporting up to 60W output. But for regular car owners, it's safer to go through a professional modification shop.