In an attempt to scratch my everpresent technological itch, I came across an interesting piece of equipment which should appeal to all technology lovers. It is a solar powered battery charger that uses the sun's energy to charge an onboard battery which can later be used to charge your personal electronics. It sounds revolutionary... just think about how you would never again have to worry about your batteries running down in your cell phone or your ipod or even your pda. At the first sign of the flashing battery icon, you simply plug the solar charger into your gizmo and you are able to charge your device without having to look around for an outlet or even carry around the power adapter.

Not only this, but you will also be doing your part to save the world by consuming less "grid" power and instead relying on the free energy of the sun.

Sounds like a win-win situation right? Well not exactly.

Basically all solar chargers work on the same principle. A solar panel converts energy from the sun into electricity and then stores that electricity into a battery which you can use to charge your electronic devices.

The solar panels vary greatly in their energy output. Some put out as little as 40mah per hour and others are near 200 mah per hour. What this means is that a 1000 mah battery can take anywhere from 5 to 20 hours to charge using only sunlight! Of course many of these chargers come with ac adapters so you can plug them in and charge them up using good old home electricity if you are in a hurry.

Even with the solar energy alone, 20 hours really is not bad if you consider that all you need to do is put the charger near a window or on your car's dashboard during the day and put it under some already running incandescent lights at night.

Once the charging is complete, you simply connect your electronic device and use the stored energy to juice up. Of course you will have to buy a separate connector for each of your devices but these are much easier to carry than a bunch of wall adapters!

The majority of devices that I have seen use some form of lithium ion battery, and this is where the problem lies.

The specific issue is that lithium batteries (like all batteries) have a limited life span. Typically they are good for about 500 charge and discharge cycles. This means if you use your charger every day it should last well over a year.

The unfortunate thing is that this battery is not replaceable. Once the battery stops charging the entire charger must be discarded. This is really unfortunate because the solar panels themselves are designed to last for several years (some even for decades!).

The construction of these solar panels is very energy intensive so the amount of pollution created and energy consumed to make these panels is not enough to justify the 1-2 years lifespan of these chargers.

To add insult to injury, our landfills will have to deal with yet another non biodegrable plastic device. Not to mention the hazzards of having lithium batteries in our landfills!

Despite the problems with lithium battery based solar chargers, there are some solar chargers which may prove to actually be just as covenient and have an increased life span. These chargers use ordinary rechargeable (nimh or nicd) batteries that can be replaced. Once the batteries stop holding a charge you simply replace them with a fresh set. This allows the charger itself to be used for many more years and it actually has greater energy saving benefits because you can charge up AA batteries for your other gizmos (like digital cameras) without the need for household current!

Lithium based solar chargers are really made more for convenience but not for energy saving or environmental reasons. The manufacturers of these chargers really need to step up and design a product that allows the user to replace the lithium battery once it goes bad.

Currenty, If you want a solar charger that is both convenient and environmentall friendly then a charger that uses AA or AAA rechargeable batteries is the best route.

I have purchased a few solar chargers and will be reviewing them in the next few weeks. Check back to see how well these chargers actually perform.