what size solar pannel to charge a single aa fully?

[PNjunction]

See the Young Ones video of University Challenge on youtube and it will all become clear.

[Logan005]

you do not wish to track the sun, you seem uninterested in using 2 cells to reduce charging time, so take your time and let the charger under or over charge and ruin your batteries and learn the hard way. Sometimes the least patient persons have the most to offer, I am patient, but I am also still learning. It takes patients to learn from a less patient person, the choice is yours.

[sensij]

You asked if there was anything wrong with your plan. There is. Some of it has already been explained in the thread, and some relates to how the solar panel works and what current you should realistically expect to see. You seem uninterested in digging in to those details at this time, but maybe with more experience, you'll think differently. I share your joy at seeing science in action in homemade devices, and am not trying to discourage your project at all. I hope you understand that solar powered battery charging equipment has evolved from the simple circuits you suggest for some very sound reasons, each step forward on top of a pile of batteries that died for the cause.

[SimonF1]

Ok, glad you reached a conclusion. After you've killed a couple batteries and are ready to learn more, we'll be here. it might be good to start with the difference between mA and mAh.

What's your ****ing problem pal?
I'm getting a bit sick of your attitude.
and no I will not come back here if and when I need help, why would I want to come back and speak to a prick like you?
now **** off somewhere else and be unhelpful there instead. tosser.

[sensij]

Ok, glad you reached a conclusion. After you've killed a couple batteries and are ready to learn more, we'll be here. it might be good to start with the difference between mA and mAh.

[SimonF1]

What have you learned? It looks like you are just ignoring the advice that was given.

I've learned loads over the past week not just from this site but others also.
I now know that the 1N4007 that i was origanaly using has a forward voltage drop off 0.6 so only leaving 0.9 to charge the battery, I've learned how to test the mAh in a live circuit using a multimeter, also the rule is not to charge batteries over 10% of their mAh so I should really not go above 190mAh on my 1900mAh eneloop's, a rule I know I'm breaking.

The idea of this post was to get advice on the solar pannel size I would need to charge 1 AA battery.

I've not ignored anyone in here and I appreciate everyones help.
If it looks like i have ignored people, then I'm sorry as that's not the impression I want to project.

I'm drawing my final conclusion on post #10 as I only need to scale my plastic housing parts to fit the new panel size.

I'm done here now and just want to thank everyone for your help and I will try and take as much information in as possible, but its overwhelming at times.

[PNjunction]

When it comes to this thread, I sometimes feel like Rick!

RIP Rik Mayall .. although I know he's still doing stand-up somehow...

[sensij]

from what ive learned I think this will work.

What have you learned? It looks like you are just ignoring the advice that was given.

[SimonF1]

Do you know how to program an Arduino to detect the EOC dv/dt of a nimh battery?

Are you kidding me? I thought everyone knew how to do that.
Hmm, no I have no idea what it even means, But maybe I should just get some solar panels that can charge a AA fully and then in time add to the circuit. but your right, it seems to be going around in circles lol.

Ok, back to the original post then.
I think I will just make the charger with only a diode and add to the circuit when and if I think I have to.
My diodes should be here soon and they are 1N5817 1A 20V Schottky low forward v drop.
and I see this solar panel, specs below

Power: 0.6W
Voltage: 2V 300mAh
Material：Polycrystalline
Size: 82x70x3mm
Weight:21g

from what ive learned I think this will work.
I will do some test and see what the values are, so I know the tolerances before I kill any batteries.
if you don't see anything wrong with the above, then that's what I will do.

I use to watch the young ones also I'm more like Vivian than Neil lol

[PNjunction]

Ok, well we're kind of going round in circles now. Do you know how to program an Arduino to detect the EOC dv/dt of a nimh battery?

Simplest solution to power your gps. Anker panel. Add an external Anker (or similar of course) external li-ion battery. AA's are old school and not likely to be found on the shelves should an EOTW event or zombie-apocalypse happen.

There's more than just AA charging going on here. Take it from an old guy - watch your heart so as not to let the seeds of hatred take root under the guise of being a preppie. This is how these seeds slip in the back door.

I'm not saying to become like Neil from the Young Ones (BEST show ever, aside from Python who set the standard), and your concerns may have some validity, but again - don't let the seeds of hatred take root.

Enough preaching. I recommend an immediate binge-watch session of the Young Ones to get some perspective and balance. (Gaw'd, I guess I'm getting old ..)

[SimonF1]

Some fantastic information here, Thanks for taking the time to do this.

when I was younger I made my own am radio from following plans and it was made from copper clad and I made my own uv box so I could photo copy the tracks from the included tracing paper to the clad using photo spray and the uv box, anyway the feel of achievement once I turned that radio on and it worked was amazing, I felt like I was king of the hill. so I really do get a buzz out of making things myself but as well as making a solar charger I think I will also buy one because one day im sure we are going to loose power here, they keep saying we are on the limit of grid overload, yet they keep building new houses and the borders our wide open so the country is filling up.
I do not see things getting better but only worse. I have a power cut about twice a month in winter and once every 2 months in the summer. and im sure one day the power will not come back on.

If any country looses its power for more than a week I think there will be some very bad things happening, looting riots etc.. so as long as I can charge my aa's I then have power to gps and that is a life line.

I will also be getting water filter portable pumps soon.

regarding the PWM module will this one be ok?

http://www.ebay.co.uk/itm/Wholesale-Red-IRF520-MOS-FET-Driver-Module-for-Arduino-IRF-520-DE-DC-PWM-SWTG-/231630138066?hash=item35ee3b6ad2:g:MIUAAOSwDNdVr8kk

[PNjunction]

Thing is, unless this is strictly for a learning experience, solar charging a AA faster than the 16-hour trickle rate, requires more than the usual benchtop hack.

Fortunately, we can use some common off the shelf stuff. How about this combo of solar panel and smart AA charger:

http://www.amazon.co.uk/Anker-Foldab...er+solar+panel

and the charger:

http://www.amazon.co.uk/SunJack-Batt...+solar+charger

The 5v output of the Anker panel (HIGHLY recommended and in size of your choice - in the UK I'd pick the largest!) drives the AA charger.

Or how about this little toy which incorporates both?

http://www.amazon.co.uk/Solar-Aa-Battery-Charger/dp/B000JG2NI2/ref=sr_1_12?ie=UTF8&qid=1453081208&sr=8-12&keywords=aa+solar+charger

STILL, the problem whether you make it yourself or use a commercial unit, is that passing shadows or temporary clouds can re-start the charging circuits of most chargers designed for indoor use. At some point, when nimh reaches full charge, there are a variety of techniques to prevent overcharge. One is dv/dt, ultimate voltage, and temperature which is needed when you charge nimh beyond the low current 16 hour rate. Outdoors, these units might re-start this process over and over again to the point of overcharge because our solar power source is not steady in the backyard.

The only solar charger that does take this into account is the Powerfilm, but that is a no no for you, so YOU will have to become the "regulator".

What exactly is your application - just a learning experience, recharging for a small led torch, or what?

One lesson to be learned here might be that the overall cost to implement a solar solution, even if small, might not be economically sound. Depending on what you are trying to do, maybe just carrying a second battery already charged would be simplest.

Ultimately, when you move beyond the 16 hour trickle rate for nimh, your cost to charge them properly is going to increase greatly.

And you are going to need that since you don't REALLY have 7 hours of sunlight despite what your eyes tell you. As far as the panel is concerned, it only sees 1 or 2 hours most to operate properly where you are, and just dribbles out nothing in the early morning and late afternoon as if it wasn't there for the most part.

[Logan005]

for something so small, you could make a simple PWM controller, or find a china company that sells a small simple PWM module.

[SimonF1]

I like the idea of a controller and I've just ordered some low voltage loss diodes. so instead of doubling up on the panels, How about if I get a 3v 300mA or similar? and what controller would you suggest? and thanks for the help btw

[Logan005]

I like it, clean looking project, that will charge your battery under the most ideal of conditions. as I recall your situation is less than ideal. for periods of days when no sun you risk damaging good batteries. since you do not wish to track the sun, consider combining 2 cells to maximize adsorption. or you could position cells to get 2X the sun hours. either way without a charge controller you still risk damaging your battery during high sun days,.