Is it an important to see "how fast" (amperes) Right now, the attached device is charging, I can recommend the PortaPow USB Power Monitor power meter.
Product link:
I use this product in combination with the anchors USB solar charger 14W 5V / 2A dual port.
I searched long for a thoroughly tolerable charging option for the smart phones in the outdoor area (eg. The motorcycle excursion / camp) and came across the solar charger anchor. The loading capacity of this device convinced.
During the day - Cloudy 1.2 A charging capacity
During the day - sunshine ca 2 A charging power really achievable!
Those looking for a solution in order to read his smartphone or other USB devices without access to a power outlet available, can the is highly recommended this product.
Product link: anchor 14W 5V / 2A dual-port portable folding Outdoor Solar Charger Charger with PowerIQ technology for 5V USB charging devices, GPS, iPhone, iPad, Android phones and Android Tablets
If you want due to charging no longer to be to be loaded and infected device dispense, I highly recommend the combination with the external battery anchor 2nd Gen Astro3 12800mAh 3 port with PodwerIQ technology (corresponding benefits see the product description). Works great!
All devices listed above are by me since June of 2014 in operation and were ausgibig tested in the combination and I'm still excited!
So far there was no anchor product with which I had really problems or that I can not recommend.
If you have questions - starting in the comments!