Bests & Worsts Reviews from Amazon

I ordered both the Opteka BP-SC4000 and the XTG Technology Solar Charger, just to compare the two. I was looking for a compact, lightweight, solar-rechargeable backup power supply for my iPod Touch, satelite GPS unit, and cell phone. Bottom line: Except for the User Guide, which is practically worthless, I found the Opteka unit to be superior in almost every way to the XTG model; here's why: 1. The specs for the Lithium-polymer battery on the Opteka BP-SC4000 claim 4000mAh capacity -almost three times the capacity of the battery on the XTG. 2. The maximum solar charge rate for the Opteka is spec'd at 250mA - more than twice the 120mA rate specified for the XTG. This should translate into significantly faster recharging of the Opteka's onboard battery for the same amount of draw-down. (Example: If your cell phone, during recharging, draws 1000ma, it will take about 4 hours of direct sun to replace the charge in the Opteka vs approx 8.5 hours for the XTG.) 3. The Opteka BP-SC4000 comes with a complete assortment of adapters to accomodate just about any small, USB-rated, battery-powered device. The XTG came with only a USB-to-mini-USB cord. 4. The workmanship on the XTG seems a bit shoddy, with noticeable gaps at the edges of the plastic sealant that coats the solar panel. The Opteka, by comparison, appears sturdy and well made. 5. The Opteka weighs about 7oz compared to 5oz for the smaller XTG (significant, perhaps, only to ounce-parsing backpackers like me). But those two extra ounces appear to translate into significantly better performance that is well worth the weight. 6. It took a little over an hour for the fully-charged Opteka to completely charge my iPod Touch. Once the iPod was fully charged, the Opteka showed about half of its capacity remaining - enough to charge another device. (I was unable to test the XTG's battery capacity in this way since I didn't have the proper adapter, but I suspect, given it's smaller specified capacity, that the XTG would barely have enough juice to fully charge even one device.) 7. The Opteka has a conspicuous and intuitive LED display on the front that tells when it's charging, when it's discharging (i.e. charging an external device), and, at any given moment, how much charge remains in the onboard battery. (When charging an external device, you do have to remember to hold down the button for 3 seconds to begin the process. Also, to check the state of the battery when the unit is idle, press the same button briefly.) The XTG has a display that performs basically the same function, but is on the back of the unit and therefore not in view when the unit is "sunning". 8. At $25.07 through Amazon, the Opteka BP-SC4000 is almost $3 cheaper than the XTG - a clear tie-breaker.