project of mine: 12v panel to charge 8 aa batteries

[Mike90250]

...A self regulating panel to match your AA charger would be the way to go.

Cool, where did you find a self regulating panel ??

[noone]

HI

I should also say be very careful of using too MUCH solar power.

I would not put a 2 or 4 AA charger directly on a 10 watt panel.

It MIGHT be ok (and if shaded may be good) but might be too much as well.

A self regulating panel to match your AA charger would be the way to go.

[noone]

AA charger and solar

I have a 12v 10 watt panel and I wanted to use it to charge AA batteries. I have a 8 AA battery case, and a blocking diode. Is there anything else that I need? This is my first solar project. Has this been done before? Any advice for me? One question that I have is how long should it take to charge the batteries?

Hi

I have not tried with 8 AA batteries but I would think you should be able to do something.

They do make AA battery chargers with built in solar panels but the one I have is very slow charging.

Instead, I simply plug a old 5 watt amorphous panel (came with blocking diode installed) into a AA charger that came with both mains and 12 volt car charger.

It works fine for 2 or 4 AA batteries for my radio, a LED camping lantern and cameras. I also plug a "torch" with a built in 3 AA battery into the panel and it charges as well....the torch has a wind up generator and mains power charger as well....but I never need to charge from mains.

The panel sits in a west facing window at home and in summer, starts charging as early as 7 am (country NSW Australia) with the sun on the opposite side of the building. There is a large sloped metal roof next door about the same height that I think is giving me a lot of reflected light.

In a good summers day, it will charge up to three times....maybe one set of 4 and two sets of 2.
Now it is getting colder It starts charging later (8 am right now and only one of the red LEDs is on, so it is charging but very little right now with two batteries in it, I just unplugged it and plugged my "torch" in instead ...3 AA battery pack in it and it is charging).

The 5 watt panel came with two power leads, one with alligator clips and one with a male cigarette lighter plug so I had a short female to female lead made up to plug the car charger lead into the panel.

The charger I use is branded Hahnel and it says...input DC 12 volt 670mA Output DC 2.8/5.6v 800mA. The panel input is therefore down a bit but it still works fine and the green LED will come on when charged.

Just occassionaly I think it gives a false charged indicator but I just unplug it and replug it and it is fine.

Of course, do this at your own risk but i have not had to plug any of my AA chargers in to the mains power for months....actually I did the other night for a camera but was not needed).

[Patafil]

I have a 12v 10 watt panel and I wanted to use it to charge AA batteries. I have a 8 AA battery case, and a blocking diode. Is there anything else that I need? This is my first solar project. Has this been done before? Any advice for me? One question that I have is how long should it take to charge the batteries?

The previous reply has you covered.

But you might be interested in this site if you like eletronic hobbies: http://www.solorb.com/elect/solarcir...rge/index.html

Or this: http://www.evilmadscientist.com/article.php/solar

David Cook also has a circuit project: http://www.robotroom.com/Solar-Recharging.html

I haven't tried these projects yet. It's just things I bookmarked.

[Mike90250]

Charging AA batteries, you need to either babysit the setup, and disconnect individual cells as they get full, or use a regular battery charger running from a 12V battery, and the PV panel keeps the battery charged.


Lets figure out what 10 watts gets you. A normal AA battery is 1 Ah of capacity, or 1.2 watt hours (V x A = W ) and (W x Hours = Wh)

So in theory, a 10W panel could charge 8 batteries in less than 3 hours. In practice, you only get about 50% of label wattage actually usable, delivered into the batteries. You will also find the small 10W panels, the 10 w is like the 300W stereo ads from the 70's, in reality, it's a tenth of that, Small panels seldom meet their power spec. And the panel is 12V, and batteries are 1.22V, so there is a problem there too.

I'd suggest looking into about a 30w panel, to charge a small AGM (not GEL) 12V battery, via a 12V charge controller (Morningstar makes several good low power controllers). Then use a 12V car power cord to pwer a MAHA AA battery charger (see the model in my .sig) to properly charge the batteries from that.

[natel]

I have a 12v 10 watt panel and I wanted to use it to charge AA batteries. I have a 8 AA battery case, and a blocking diode. Is there anything else that I need? This is my first solar project. Has this been done before? Any advice for me? One question that I have is how long should it take to charge the batteries?