what size solar pannel to charge a single aa fully?

[SimonF1]

Yes this setup that you suggest has crossed my mind several times and in time I would love to be off the grid, But its another project altogether.
For now I would just like to keep it portable so a folding unit might be my best bet, but what would be the minimum size I can get away with?

this was my first attempt I used a 1.5v 0-300mA panel.

[Logan005]

then you should purchase a 100 watt panel and a 35 amp hour 12 volt battery and charge controller, from that battery you can configure circuits to charge any or all of your single cell batteries. day or night, rain or shine. that is a basic 12 volt system and your simple need is well within it's capacity, in fact you could also use a small amount of emergency power from this bank during power outages. If you wana go even bigger well the sky is the limit. but best to learn to care for a single 12 volt Flooded Lead Acid=FLA battery for now and learn to manage such a small source of power. If you have access to secure outdoor space you can make a rolling set up that you can position for optimal sun hours, but cloudy skies need 2 to 3 X the wattage

[SimonF1]

Hi Logan005
I don't want to track the sun, I just want to put the solar panel down and let it do its job, in fact it might even be cloudy so no sun to track, I would rather go big and not rely on good weather, that's why I said "in English winter time" because we do not see the sun a great deal, we don't see the sun a lot in some summers lol, but im hoping if I go big then I can still get enough power into a single cell aa battery. so I need to go from fully discharged to fully charged in 7 hrs on a cloudy cold day.

[Logan005]

I got a smart charger from e-bay, charges Ni-cad, Ni-mh and lifepo batteries, in four single banks. It operates from 6 volt or USB and has a nice display with diagnostic's also can discharge batteries to renew old cells that have a memory. it could be possible to run directly from solar, but you would have to manually track the sun all day to actually top off fully discharged batteries. If your just trying to figure the math, then you have to take into account, solar sun hours, tracking increases your sun hours and allows you to actually charge your batteries more properly.

[SimonF1]

Hi PNjunction.
Yes I know what you mean on the disappointed issue I've already been through that before i posted in here.
I will get one of those foldable solar chargers eventually but not from USA as it cost crazy amount in P&P to the UK then there is customs to add on some items, so buying from USA is a big NO NO.

I see RavPower they seem to have a good reputation and I can buy from ebay UK if I do decide to get one of them.

The idea of charging 1 aa battery is still my goal it would be useful as lots of gadgets take 3 batteries so we all end up with this odd battery as they can only be charged in pairs on most chargers.

[PNjunction]

Hi SimonF1, welcome aboard!

Those little AA trickler circuits can be a lot of fun, but please don't get disappointed if they don't charge in a reasonable amount of time.

The reason for this is that despite having 7 *visible* sun-hours at your location, as far as a solar panel goes, it isn't as efficient as our eyes are, and thus in reality, you may only have 1 hour near noontime, especially in winter for it to actually work at it's fullest capability. This is known in the solar world as "solar insolation hours". Right now, you only have 1 hour at most as far as the panel is concerned!

Another consideration is that nimh can easily be overcharged by "tricklers" eventually. 16 hours on a trickle is the maximum, but most people don't know that going longer is slow-cooking a nimh battery to death, even though they may not feel the slightest bit warm! Perhaps you've experienced this with small household vacuums that sit in their charging holders forever, yet fail to work shortly after purchase. Or perhaps small PMR446 handheld walkie talkies that quickly fail to work.

So please, have fun with those circuits, but do NOT be disappointed knowing what you know now.

If you want to take it to the best level with a commercial product that will charge the batteries properly, and KNOWS how to deal with vagaries of solar charging (unlike a lot of other camping style junk chargers out there), this is worth saving up for:

http://www.ebay.co.uk/itm/NEW-PowerF...-/141056376653

This is a 4-AA unit, and NOT the AA/USB combo. The 4-AA unit works much better, especially in your locale. Thing is, you can only charge in pairs (2 or 4 at a time). Doing only 2 at a time would be the quickest.

Have fun!

[SimonF1]

This is great and just what I've been looking for.
Thanks for this DanKegel

[DanKegel]

There are lots of pages on the subject, e.g.

http://www.reuk.co.uk/Solar-Battery-Charging.htm

http://www.voltaicsystems.com/blog/solar-charger-tutorial-part-1/

Going by the first page's suggestions, a 2 volt, 200mA panel might suffice for a single cell trickle charger.
http://www.ebay.com/itm/like/311037425212 appears to be a 5 volt 200ma panel for $3.

Doing it right is harder than it sounds Be prepared to toast a battery or two if you try to do it without understanding battery charger design.

Good luck!

[SimonF1]

First of all, Hello and hope everyone is having a great new year so far.

I know very little about electronics and just need a little help getting the right components.
I want to make a single cell AA solar charger that can charge a single AA 1900mAh eneloop battery in English winter time, So that's about 7hrs light per day.
I would like it if I can leave the battery in the charger without it loosing its power at night time or in very overcast conditions.

I just need a link for the solar cell I need and from ebay uk would be best place for me to get it from.

Please can anyone post me a link for the solar cell I need please and any other components I may need.

Kind Regards
Simon