PROS / This phone charger is sturdy, light and thin.
CONS / It requires a mini-USB connection to charge from USB rather than the standard micro-USB.
VERDICT / The SC4000 is durable and lightweight, which gives it excellent portability. The second-generation panel fits easily in your pocket so you can take it almost anywhere.
The Opteka BP-SC4000 is one of the most portable device when compared to the best solar phone chargers in this review. Its size, weight and the materials from which it is made gave it the best portability score of any charger we tested. It’s non-reflective, matte black finish gives it a stylish appearance. It has a composite makeup consisting of a durable plastic frame holding an epoxy panel.
This is a second-generation solar device. The solar cell is made of an epoxy resin that allows it to be thin and lightweight. Panels like those in the SC4000 are the future of solar technology, but there is still room for improvement. The efficiency rating of the panel is below the average crystalline silicon panel of similar size, but just barely. The SC4000 still performs well enough to be included in a review of the best solar phone chargers.
It took us around nine hours to charge the 4,000 mAh battery to full capacity in the sun and four hours with a USB. The SC4000 allows pass-through charging so you can charge your phone while you charge the battery pack. As with any solar cell phone charger that has this feature, you might want to plan ahead before using it because it's possible you'll drain the battery before it has time to charge back up.
Note that the solar charging time is more than twice that of the USB charging time. While this is not a big issue, it does present a good example of the limits of solar technology. When your phone is charging from the SC4000 while the SC4000 is charging from a USB 1.1 outlet, it is going to be pretty close to a one-to-one ratio of power in and power out.
Like any solar charger, the SC4000 is not going to offer you a better charging ratio than outlet power. The advantage the SC4000 has over a regular battery pack is that even without plugging the pack in to an outlet, the SC4000’s batteries are still charging. This is particularly useful when an outlet is not available.
Just about the only thing we didn’t like about the SC4000 was that it has a mini-USB connection to charge its battery when micro-USB is generally the industry standard for mobile devices. It does come with mini and micro-USB connectors – along with an assortment of feature phone connectors – but that all seems like a lot to carry around.
The Opteka BP-SC4000 is barely larger than a Samsung Galaxy S5 and weighs considerably less. Its plastic construction and epoxy panel make it one of the lightest on our review. Its overall output and reasonable efficiency make it worth considering for your next solar phone charging device.