Re: Portable Solar Power
The problem with these little pocket solar chargers is that they almost always under-power the solar.
A little math...
These products usually have a solar module capable of between 1/3 & 1/2 Watts. In full sun. So, in the case of the first product mentioned, it would take approx 12 hours to fully charge its internal battery (not the 8 as it's specs state... sorry Chinese manufacturers, but the numbers don't add-up).
In the case of the second product mentioned in this thread, the battery is a lot larger, and so it will take almost 24 hours of full sun to charge it. Note the reviews on the product page... most of them complain about a full day of sun, and barely anything of the battery charged.
NOTE: in non-optimal exposure, the rule of thumb I use for portable solar is 3 peak-sun-hours per summer day. Meaning that a 1/2Watt panel will produce approx 1.5 Watt-Hours of power. This is approx 1/4 of an iPhone battery for example. Do you use more than 1/4 of your phone battery in a day?
The first product has a 6.5WHr battery, and the second has almost 15WHrs. That means approx 4 days to fully charge product #1, and approx 10 days to charge product #2. You don't have to fully charge either product to use them of course.
You can also do better if you leave the charger outside at the perfect angle in full summer sun, but that defeats the portable utility of the product.
Sorry for the lecture, but I don't want to blow any smoke up your skirts when talking about what these products can & can't do.
They make great back-up batteries (product #2 offers great capacity!), but the solar is a novelty at best.
When shopping for a portable solar charger, I recommend drawing the line at 1W at the very least on the solar panel, and if they don't tell you, then figure that 1W requires approx 20 sq-in of solar cell. 1W solar with 8WHrs of battery storage will give you some practical, sustainable power for a phone or GPS.
Feel free to email or reply to this thread if you want my opinion on any specific product. I won't spam, so I won't make product recommendations unless they are asked for.