Is It Safe To Charge Your Phone In The Car? (And Should The Engine Be Running?)

Considering how important your smartphone is in your everyday life, from keeping you connected and helping you stay productive on the go to being a source of entertainment, you'll want to keep it charged at all times. To make that happen, it's essential to charge it at every possible opportunity, including during your commute. Thankfully, you have several options to charge your phone in the car: using your car's USB port, plugging a charger into the cigarette lighter socket, or using a built-in wireless charger. But is it actually safe to charge your phone in the car, and can it affect your car's battery? 

When you charge your phone in the car with the engine running, the alternator recharges the car's battery by constantly converting mechanical energy into electrical energy. Since the alternator essentially functions as a generator, there is usually enough power to support both the car's electrical components and your smartphone. That said, you still need to follow the proper charging practices, such as using a reliable charging cable, preferably one sold by the smartphone manufacturer. You should also ensure the cable is in good condition and free from any kind of damage. If you're using a USB car charger, avoid cheap or low-quality ones, as they can cause problems with your phone and the vehicle's electrical system.

In terms of battery capacity, your car's battery holds significantly more power than your smartphone's, which is why smartphone batteries are typically measured in milliamp-hours (mAh) while car batteries are measured in amp-hours (Ah). The higher capacity means that even when the engine is off, there's enough power in your car's battery to charge your smartphone, and you typically won't experience any problems. 

However, because the alternator is not running while the engine is off, the car's battery won't get charged simultaneously. So, charging your phone for an extended period of time can cause your car's battery to drain. While this shouldn't be a problem for most vehicles, if your car's battery is already old or weak, you could experience problems while starting the engine. 

Overheating is another factor to consider when charging your phone in the car with the engine off. That's because smartphones tend to generate heat while charging, especially if you're using them for things like navigation, streaming, or gaming. When the engine is off and the air conditioning is not running, this heat can build up inside the car, especially under direct sunlight. The rise in temperature can affect your smartphone's battery and may even cause it to stop charging altogether. That said, as long as your car's battery is healthy and you're using quality charging equipment, you are unlikely to experience any problems, whether the engine is on or off.