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Reviews > Electronic Devices > Solar Chargers > Exponent Flex 5 System with Batt Pak > Bill Jeffrey > Field ReportICP Solar Technology Exponent Flex 5 System with Batt Pak - Field Report
Tester Personal Biographical Information Bill Jeffrey
I have over 30 years backpacking experience, starting with Scouting as a youth. I am currently the High Adventure Leader for a Scout Troop. I try to get out once or twice a month, plus at least one week-long trek each year. My trips are of two types. First, I am hiking the Pacific Crest Trail in sections, and generally use a lightweight approach on these typically solo trips. Other trips with family involve more traditional backpacking equipment. Terrain varies from sea level to 14,000 feet (4,300 m), desert to mountain, and trail to cross country, occasionally including snow travel. I usually carry several electronic devices with me - cell phone, ham radio, digital camera, and GPS - all of which eat batteries. This is the second of three reports of the ICP Solar Technology Exponent Flex 5 System with BattPak based on use in the field. The First report described the system in detail. That information has been incorporated below. This report is based on field use over a two-month period. The final report will update this report based on additional use after six months. Product Description: (To skip this section and go right into the Field Test click here.) Two separate items are being tested:
Field Test: While most BackpackGearTest reviews endeavor to test a product under varying weather conditions, the ICP system simply will not work without sun. Therefore, my tests were conducted during daylight hours without extensive cloud cover. Temperatures generally were between 50 and 80 F (10 and 27 C). A typical backpack trip during the test was a weekend in the Anza-Borrego Desert at 2,000 feet elevation (600 m). The daytime temperature ranged from 50 to 80 F (50 to 80 C). I attached the Flex panel vertically to the back of my ultralight backpack using a nylon strap through the two grommets at the end of the panels with the power connector, looping the strap through two lashing points on my pack. I started to secure the bottom of the panel to the ice axe loop, but found the panel was reasonably secure without it. I had previously attempted to attach the panel horizontally to the top of several packs, including a large frame pack, but in every case at least one panel ended up hanging over the size of the pack. I observed that the voltage dropped if any panel was shaded, and therefore decided that it was best to at least have full power available some of the time instead of lower voltage more of the time. I placed in the BattPak 4 AA batteries for my GPS and 3 AAA batteries for my LED headlamp. All batteries were 500mAH nickel cadmium batteries. The batteries were partially depleted. I had deliberately left my headlamp on high power all night. Heading out west across the desert to our first stop, the panel was facing the morning sun. I checked the LED indicators and found the light was not on, possibly because of the low angle of the morning sun. I figured charging would begin as the sun rose higher. However, during my first stop an hour later, the LED was still not lit. Checking the system, I found that the cord plug connecting the Flex 5 had pulled out of the BattPak. While the other extension plugs fit snugly, the connection to the BattPak is loose. I plugged it back in, and still nothing. Checking further, I found that the batteries had loosened in the case and were not all in full contact. Reinstalling the batteries, and placing the panel so it faced directly into the sun, the charging indicator finally was lit. The red LED is difficult to see in the sun, and I had to shade it to make sure it was on. Continuing on, I checked on the progress periodically. While heading west or north, the charge indicator was often on. However, a turn east or south caused charging to stop. Being a short trip to a favorite spot, I arrived at my campsite at noon. As there was a rocky hill to the southwest, I placed the system flat on a small bush a short distance from camp while I explored the area, known for pictographs and petroglyphs, as well as large rocks and rock caves to explore. Returning to camp a few hours later, the panels were again in the shade. The AA batteries would not power my GPS. The AAA batteries did work in my headlamp, but with what seemed to be less light output then there had been that morning. Thankfully, I had spare alkaline batteries with me. Attempted to use the system in cloudy weather resulted in charging only during mid-day. Similarly, the early morning and late afternoon sun apparently does not provide sufficient power during the winter when the sun is at a low angle. I noticed a similar effect in my truck, where I could get enough sunlight through the windshield when facing into the sun, but not when at an angle to it. Attempts to use the Flex 5 to charge my cell phone resulted in questionable performance. In low light, the cell phone indicated that charging was complete, although the battery indicator then indicated a low battery when the solar panel was removed. I have not had sufficient time to fully charge the cell phone battery with solar power so far. Use of the BattPak charger with AC power was as expected and as advertised. Use with AC power is of minimal use for backpacking, other than an initial charge before a short trip. Ease of use: The system as delivered is easy to use - plug the pieces together and place in the sun. The complications are mostly location: where to mount on a pack and where is the sun shining. The batteries install easily in the BattPak, although the springs holding them against the contacts are a bit weak for rough hiking. The instructions are easy to follow, although there is some confusion about how long charging will take. The LED status indicators on the BattPak are not bright enough to be seen in full sun, which is, after all, where this system must be used. The plug connecting the Flex 5 to the BattPak worked loose during my hike, terminating the charging process prematurely. Portability: I found it easy to strap the solar panel to my backpack, although it sometimes had to be removed to access the contents of the pack. The bigger difficulty is that the panels are too long to fit on top of my packs, and mounting them on the back results in them only providing power while I'm walking away from the sun. They work much better while in camp. Weight: For me, weight is crucial. It does not make sense for me to carry over a pound (.5 kg) of solar panel, cable, and battery charger when I can carry a few extra batteries that weigh less than an ounce (28 g) each. Battery charging time: Wide ranges of time to charge batteries for various devices are noted on the website. Charging time in full sun has taken a full day, although a sun exposure for a full day has not always been available. Sunshine, or the lack thereof: I was a bit surprised how quickly power output dropped during overcast or cloudy conditions. I was more surprised that the angle of the solar panels appears to be more critical than I had expected. Durability: So far, the material has held up well with no damage. Jarring from rough handling of my pack caused no damage. The claim of being "fully weatherproof" has not been tested, although it is an interesting claim for a product that needs full sun for proper performance. Summary: This could be a very useful tool during an extended natural disaster and a fun gadget on car camping trips. However, in my opinion, it is too heavy and awkward to use for backpacking. Next: I will continue to use the system on car camping trips and at home. I want to further explore use both for charging AA and AAA batteries and for charging my cell phone. Field tests will be generally in the Anza-Borrego Desert. Elevation will range from sea level to 2,000 feet (600 meters). I will look for sunny weather for testing, as the solar panels do best in those conditions. I will continue to focus my test on using the product components to charge batteries in camp. However, I do want to experiment further with charging a cell phone. While I had hoped to test using the solar panels to directly power equipment, my cell phone will not function without a battery installed, and my radio requires more regulated power. The Flex 5 instructions say to use it "in conjunction with your electronics' car charger which serves as a regulator" to protect from the higher voltage of the solar panels. This is not practical for my handheld transceiver, so I will instead see how well it can charge its 7.2 volt, 1100 mAH lithium ion battery using its portable charging dock.
Reviews > Electronic Devices > Solar Chargers > Exponent Flex 5 System with Batt Pak > Bill Jeffrey > Field Report | ||||