Very handy, but charge current is too low to smartphone (SGS2) to operate as Navi and charge simultaneously

+ Very handy, the cable can be rolled up and therefore there is no cable clutter when it is not needed
- Charging current is too low to charge the smartphone useful and at the same time operate as Navi.

I had my empty Samsung Galaxy S2 plugged in the car and at the same time uses the Navifunktion of Google Maps.
After an hour, the smartphone was charged only to 2%, ie 50 hours of driving would have been necessary to fully charge it.
Thus, it has a similar charging performance as the USB port on my notebook (500mA), the charging current there is not enough even to big to surf with and recharge.
Either or :-)
Unfortunately I do not have enough that to recharge your smartphone on vacation during the car-travel times and at the same time to navigate it.
The original 220V charger it creates in less than three hours to 100% charge, despite surf and download in Wi-Fi.
I'm going to look for a new car charger, in which the charging current is indicated and min. 1A charging current has.