Why Is My iPhone Charging So Slowly?
If your iPhone is charging slowly it's generally due to one of two reasons: the charging port or the charging source.
Apple introduced the Lightning port with the iPhone 5 and ever since there have been reports of slowly charging iPhones. Due to the shape of the port it's common for debris (like pocket lint) to get stuck inside, which can partially block the iPhone charging connection and slow the charging process.
Cleaning the iPhone charging port can be done by gently rubbing a toothpick inside the connection. Alternatively, using a can of compressed air will often solve the problem.
If the iPhone charging port is not blocked by debris, the issue may be because of the iPhone charging source. The charging speed is determined by the amperage coming through the power source: the higher the amperage, the faster the charge.
Charging via a laptop or car charger only provides about 500mAh (amperage). Using the standard 5W iPhone Charger can provide 1 amp (1000 mAh), resulting in a faster charge than a laptop or car charger. The iPad wall charger (10W or 12W) will allow for 2.1 amps (2100 mAh), providing the fastest charge of all.