In the last three years or so, companies have been developing solar-powered portable chargers that soak up sunlight and store the energy, ready to give your gadget a jolt when the “low battery” light starts blinking. The products that have been rolling out over the past three years vary in size — some fit into a purse or messenger bag, others can clip onto a backpack — and range from $30 to more than $100. They come with a handful of adapters that fit hundreds of phones and other devices.
Considering a solar-powered charger? Keep this in mind:
* They work best with small gadgets, such as cell phones and iPod-like media players. They don’t deliver enough juice to power a laptop.
* They are meant to charge your device while you’re not using your gadget or to extend your battery life just long enough to wrap up a phone call or hear a few more songs on your music player.
* The solar panels store energy faster when in direct sunlight, preferably with the panels tilted toward the sun. So, as the sun moves through the sky, you should reorient your solar panels for maximum efficiency. Bear in mind, though, that it’s not a requirement. They will collect power even on overcast days, just not as fast as in direct sunlight.
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* You have to expose these chargers to the sun for 12 to 48 hours to give your gadget a full charge, but you can get up to 20 minutes’ use — enough to make an emergency phone call — after charging for an hour.
* They don’t work solely on sunlight. You can plug them into electrical outlets or a computer’s USB port to store up juice faster than they can via the sun’s rays.
* Before buying a portable charger, check the manufacturer’s Web site to make sure it will work with your gadget. Though the charger comes with adapters that fit many devices, yours may not be among them, or your device may need more energy than the portable charger can deliver.
* The time it takes a portable charger to fully charge your gadget depends on the charger and on your gadget’s power requirements. A charge time of six to eight hours is not uncommon.
* As we increasingly demand more from our portable devices, newer ones demand more and more power, so the charger you buy today may not kick out enough energy to sustain the gadgets you buy next year.
* All solar-powered chargers are not created equal. The most useful models deliver enough juice to fire up your gadget and keep it going, and they have their own replaceable battery, so when the charger’s battery is used up after 500 to 1,000 charges, you can simply replace the battery instead of throwing away the charger. The best chargers also should be able to store a lot of energy in reserve.
How will you find out these things? Check a charger’s specs.
What to look for: Some questions and answers
Looking at a product’s technical details isn’t the most fun you’ve ever had, but it’s the best way to know if a portable charger has a chance of powering your gear. Here’s how to figure out what you need to know when you are looking at a charger’s specs:
Can it deliver enough juice to keep your gadget going?
Check the maximum output. That’s how much power the charger will send to your device. It will be listed in watts (4 watts or higher is good), in current (measured in milliAmps, abbreviated as mA) or mA hours (mAh): 700 mA is OK for small phones and MP3 players; 800 mA can power slightly bigger gadgets; 1,000 mA should handle smart phones, PDAs and many other portable hand-helds.
Can it store a lot of energy in reserve?
To check capacity, look at the internal battery’s rating for milliAmp hours. A rating of 1,000 mAh is so-so, 1,300 mAh is better, but an 1,800 mAh battery can hold a lot of energy in reserve. A rating of 1,000 mAh or lower isn’t a deal breaker, but higher is better. The more capacity a battery has, the more times it can juice up your gadgets before the charger needs a refill from the sun, a wall outlet or your computer’s USB port. However, higher-capacity batteries take longer to charge than lower-capacity models.
Solar-powered portable rechargers aren’t the end-all-be-all yet, but companies are working on this because they know there might be a market. The more popular these chargers become, the more companies will invest.
Alternative sources of energy
Carrying a solar-powered portable charger is more convenient than carrying around your gadget’s wall adapter, but there are other ways to roll:
* Buy an extra battery to charge up and carry around in case your phone or MP3 player starts losing juice. For devices that don’t have replaceable batteries, a portable charger makes sense.
* Buy a charger that lives off AA batteries, such as the Turbo Charge ($20; turbocellcharge.com). If you use rechargeable AA batteries in those chargers, you’ll be keeping batteries out of landfills.
* Buy a charger that gets its juice from an electrical outlet, such as the Powermonkey ($50; thinkgeek.com; 703-293-6299) or from your computer’s USB port, such as the Ecosol Powerstick ($70; powerstick.com).
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A GUIDE
Here is a roundup of solar-powered chargers. It would be very difficult to try each charger with every cell phone and music player to gauge, so we provide these models as a guide, not as recommendations. To see if a charger might work with your gadget, look for a compatibility list on the charger manufacturer’s Web site, given below.
Solarstyle SC002
$40; solarstyle.com, click on “view our entire line”
The SC002 can power a variety of devices, from small MP3 players to smart phones and PDAs. It can fully charge with about 8 hours of direct sunlight.
Reware solar bags, backpacks and totes
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$150-$300; rewarestore.com
Reware, makers of the Juice Bag, puts solar panels on laptop bags, beach totes and backpacks. They aren’t the most stylish bags, but they kick out enough juice to power even hand-held vacuum cleaners. Also, for smart phones and portable games, their $150 Power Pockets can be unfolded to capture sunlight, then folded up to carry with you.
Solio Hybrid 1000
$80; solio.com
The H1000 is best at powering smaller cell phones and MP3 players that cannot play video. The H1000 can fully charge with about 12 hours of direct sunlight.