Charging iPhone with USB

[kelvincheu]

I notice that when using the USB charger in the arm rest to charge iPhone 5, the charging is very slow compared to charging from my laptop USB or from the wall outlet at home. Does anyone has solar experience? Why is it so?

 

[nizzy1115]

Because the port wasnt intended to have the power to rapidly charge your device, just enough to keep it powered as you use it.