What exactly can you do with a low wattage Panel?

[SiL3nT]

I'm quite new to solar panels, but will a 10 or even a 5 watt solar panel be able to charge multiple AA/AAA batteries at the same time? How about a cell phone? Ipod? Also, how long would it take to fully charge any of the above? Any help would be appreciated.

[lile001]

I'm quite new to solar panels, but will a 10 or even a 5 watt solar panel be able to charge multiple AA/AAA batteries at the same time? How about a cell phone? Ipod? Also, how long would it take to fully charge any of the above? Any help would be appreciated.

Cell phones, PDAs, Ipods and the like need a specific voltage. Your panel, floating between maybe 0 and 18 volts for a 12 volt panel, will likely damage a cell phone if you plug it straight in.

Likewise AAA's, which require a specific voltage. There are loads which are made to run on the varying output of a low wattage panel - my solar water heater in fact uses a 10 watt panel to drive the pump.

If you are an electronics hacker you could construct a regulator that would be safe to plug into your cell phone etc., but unless you already own a soldering iron I'd not recommend this.

A 10 watt panel is a keen thing to demonstrate solar with. Me and a 14 year old friend made just such a thing for an Earth day fair - complete with a scavenged tape recorder motor that spins a little flag when the sun shines.

[Mike90250]

You can use a small panel, to power a 12V charger for AA/AAA batteries. Many of the AA chargers actually run off of 12VDC (think Automobile lighter plug) Charge time depends on wattage of your panel, # batteries being charged, and if you are doing a fast or slow charge.

[SiL3nT]

So how would I go about charging a couple of AA/AAA batteries? What would be the first step? I'm a complete noob. I'm looking at 5W and 10W polycrystalline panels. I'm looking to go the cheapest route possible. I don't want to buy a 10W panel if its complete overkill to charge AA/AAA batteries.

[Mike90250]

Most nimh chargers really want to see 12V @ 1 amp, or so, because they may be charging 1-4 AA batteries less batteries, less power needed.

10W (1.5V 6.6A), if harvested perfectly, to a 2000mA AA battery (2.0aH @ 1.2V=2.4w), would take about 20 minutes, and really toast the cell, they are not designed to charge at that high of rate.

And we know a 10V panel is very likely going to be in reality, a 18V .5A panel, and .5A would take 4 hours to charge a AA battery.

Any charging control circuits will intorduce losses, and charge at a slower rate.
More than 1 battery will increase the charge time.
NiMh batteries, if not properly charged, will die early.

I like Maha chargers and have bought from

http://www.thomasdistributing.com/shop/chargers-c-147.html

But it is more complicated than just wireing a panel to a charger car cord.

[Sunking]

So how would I go about charging a couple of AA/AAA batteries? What would be the first step?

Take a couple of years of electronic circuit design so you can build a custom charger.

[lile001]

Take a couple of years of electronic circuit design so you can build a custom charger.

Naaah. Take a couple of bucks down to Radio Shack and buy a 12V AAA charger, hack them together. No electronics degree required.

--Lawrence

[Sunking]

Naaah. Take a couple of bucks down to Radio Shack and buy a 12V AAA charger, hack them together. No electronics degree required.

Maybe you are right, but Americans are poorly educated and most have no math skills beyond My Dear Aunt Sally if even that. Obvious US Politicians cannot balance a simple check book and they have degrees in BS.

[lile001]

Maybe you are right, but Americans are poorly educated and most have no math skills beyond My Dear Aunt Sally if even that. Obvious US Politicians cannot balance a simple check book and they have degrees in BS.

There was a time not long ago when a majority of Americans could understand the technology they used everyday, such as thier car. Oil changes were DIY affairs, if you didn't know how then your brother did. Since then, technology has gotten more complex, and Americans have gotten less technical. I encourage every 14 year old kid I meet to go into math, science or engineering, and then haul them into the electronics lab to make it sink in. One time we were making a pancake breakfast for the Church. I asked this kid how many pancakes we would need, given we'd sold "X" tickets. But he had to give his answer in binary, in his head. "No problem" he said, and proceeded to do it.

[mg2969]

I like this device for charging AA's in
To do AAA's, a double AAA battery holder with leads can be attached from radio shack or Frys

http://www.harborfreight.com/cpi/ctaf/displayitem.taf?Itemnumber=41427