It's been a great summer with plenty of sunshine (when not obscured by forest fire smoke) to test the RAVPower 24 Foldable Solar Panel and RAVPower 26,800mAh Power Pack. (Original post on the test can be found here)
We are happy to report this setup will fulfill our desires to provide camera battery charging to our photo tour guests while trekking in the Himalayas of Nepal (Bhutan's trip is van/hotel based, so we will have plenty of charging capabilities without solar). We will employ one solar panel and power pack for each three guests, ensuring the most vital camera batteries are charged.
The Concept
We have used solar panels in Nepal before, but back then battery demands were less. Battery sizes have grown as our cameras and communication gear becomes more power hungry. Solar panels are a great idea but can be problematic to keep pointed at the sun while traveling or in camp. We wanted a solution that could handle the intermittent challenge of strapping a solar panel to a guide's backpack or the bags on top of a yak or dzokyo (a hybrid between a yak and a cow). We also wanted a system that is easy for guides to use so they aren't spending time hassling with gear instead of instructing guests.The Gear
We chose the 24W solar panel as it should give enough power in full sun and be able to still deliver partial charge when shaded. The RAV Power solar panel comes with a maximum output of 4.8 amps between 3 built-in USB ports (with a maximum of 2.4 amps per port). Its foldable and weighs about 1.5lbs. It also comes with small carabiners to make attachment easy (as it has four grommets on the corners).
To store the solar power, we chose the RAVPower 26,800mAh Power Pack because that's a lot juice. Considering most DSLR batteries store between 1600-2500 mAh (milliamp hours), we surmised we could get a solid 10-12 battery charges per full power pack (considering some loss during transfer and temperature differences). The power pack will allow us to top it off while trekking and shooting and then disperse that power to client batteries while we eat dinner.
The unit charges via a microUSB port making it easy charge anywhere (including at hotels and in vehicles) and pumps out the power through three USB ports, each with a maximum 2.4 amps (and a total 5.5 amps output for the unit). It has one button to turn it on and four lights to indicate power level. Dead simple, which is perfect when you're far from tech support.
Lastly we tested a BM Premium Dual Bay USB charger. It is also charged via a microUSB connection (we love non-propietory adapters for redundancy) and has two interchangeable adapters for various battery types. Before we leave for Nepal we will ensure we have adapters for all the various battery types our guests will be bringing.
Each bay has an LED that is either red while charging or green when finished. Again, dead simple.
The Tests
We tested this setup during the summer as our batteries became depleted from normal use. We also used it to charge various Apple products, like an iPhone 6 and an iPad Air 2.
What we found is a problem with shade. When charging an iPhone, iPad or even the dual bay battery charger, if charging was interrupted by shadows on the panel not all devices picked up where they left off. The Apple products weren't 100% reliable in these cases, to the point where we will not trust the panel to continually charge such devices unless we lay the panel in direct sun. The battery charger was also finicky but typically resumed where it left off (noting that the unit states it needs a minimum of 2.1 amps in order to charge).
The best solution we found was to always charge the power pack and then, simultaneously, hook up any devices to the power pack. The power pack always failed perfectly, meaning whenever input from the solar panel was cast in shadow, then returned to ample sunlight, the power pack was ready to keep charging (as indicated by a flashing LED).
The added bonus is the power pack is also capable of more total power output (5.5 amps compared to 4.8 amps) through all three ports.
The Results
We calculated the power pack lost 25% of its power (signified by one of the four power LEDs going out) when charging two Canon LP-E6N batteries (1885 mAh each) from 40% to 100%, one iPhone 6 (1800 mAh battery) from 25% to 100% and one iPad Air 2 (27,000 mAh battery) from 75% to 100%. Those are the average results from various tests and since we can't measure the actual storage capacity of the power pack, we're forced to use some guess work.
To charge the power pack back to 100% from about 75% power, we left the solar panel and power pack in the sun for four hours, on average.
This, to us, best represents a daily cycle of expected use. Sure, there will be days when the sun isn't out all day and that's why we have plenty of capacity. Also, as the panel can put out 2.4 amps per port, one can charge the power pack and another can charge batteries while we are on the move (with the understanding that the batteries might not be optimally charged, but something is better than nothing).
Conclusion
Bringing two RAV Solar Panels and two Power Packs will help us ensure our six guests are never without power to get the shots they want. Not only that, it will give them piece of mind when they want to go crazy or in situations where there is a large draw of power, such as astrophotography or use of video recording.
On days we know our porters or dzokyo driver will make it to our next destination before us, we can send them ahead with panels and power packs to lay out in the blissfully full sun of the Himalayas for maximum charging.
More and more teahouses on our route are offering electricity but it most often comes with a cost. And it is not always reliable (see example at right). After we leave Namche Bazaar, the options quickly decrease and we plan that this setup with allow our guests to shoot until their hearts are content.
