Battery Trickle Charged Solar Ruby Amp

[Scruffie]

Title's a Mouthfull 

Over this Summer, i'm Gunna want to play guitar and have portable amplifier use for MP3 Players quite a bit, so... I'd quite like to build a Portable Ruby amp but be able to Trickle Charge a Rechargeable 9V Battery (I will consider also using a 6xAA Pack) Via a Small Solar Cell over the day so that it lasted a little longer and also could be played at night, it doesn't have to last for ever or even be hugely loud but an extra half hours use per session would be nice, it will be in full sun all day (If the weather permits). I also might be away from home a few days at a time so without bringing extra batteries it'd be nice if it would just start working again if I left it out all day like an emergency charge.

I'm Hoping to fit it into a 1590Bish sized enclosure with the speaker inside and the solar Panel on the back, sound quality from the speaker really isn't too much of an issue so it being small and in an enclosure like that isn't too much of a bother, it may not be a 1590B in the end but I want it to be of a small size regardless.

For Solar Cells, I was looking at something like the 9V one here - http://www.futurlec.com/Solar_Cell.shtml Small Dimensions, Reasonable Current and 9V and best of all, it's under $10.

Now, I can't claim to know anything about Trickle Charging or Solar Power really so is this feasible and where should I be looking for information?

Something around this sort of level of simplicity would be ideal -
http://www.sentex.net/~mec1995/circ/bcgla2.htm
http://circuitdiagram.net/200mahour-12v-nicad-battery-charger.html
http://www.lm317-circuits.com/12v-battery-charger.html

Saw a couple of threads on here but none of them really went very far, is it just not worth the effort? If not i'll just go with 6xAA and hope for the best.

[Ice-9]

I'm wondering if those solar lights that you stick in your garden that you can buy from the garden centers might have all the circuitry that you need already in them. Just a thought.

[Scruffie]

I'm wondering if those solar lights that you stick in your garden that you can buy from the garden centers might have all the circuitry that you need already in them. Just a thought.

I did think about those too... I'll have to check one next time I see some.

[maarten]

Have a look at the capacity of your 9V rechargeable battery (or that of the six-pack, which is probably higher - so you can play a little longer at night). Charging is typically done at 10% of the battery capacity. Given some efficiency losses, this is the reason why manufacturers will advise you to load their 9 volt for about 12 to 14 hours. After this period, trickle charging may be applied: this is to compensate the losses of discharging, which begin after charging has ended. The trickle charging may even charge the battery further, but the trickle is too small to harm the battery - this is also why trickle charging won't work for you (I think): it won't charge you battery enough in just one day's time...

Probably you can find more information on the net, or try to find a book in a library on the subject.....
I am not quit sure, but I would guess that you will need a higher voltage solar cell, as the charger basically is limiting the current from the solar cell to the battery - this will take some voltage. Prabably 2 cells of 6 Volt/16 mA in series could do it (they call it 6 V, but the peak V is actually lower, and the real voltage which you will get will still be lower - this  will depend upon where you live - how much sunshine, clouds etc.). Hope this is of some help!
Maarten

[Scruffie]

Have a look at the capacity of your 9V rechargeable battery (or that of the six-pack, which is probably higher - so you can play a little longer at night). Charging is typically done at 10% of the battery capacity. Given some efficiency losses, this is the reason why manufacturers will advise you to load their 9 volt for about 12 to 14 hours. After this period, trickle charging may be applied: this is to compensate the losses of discharging, which begin after charging has ended. The trickle charging may even charge the battery further, but the trickle is too small to harm the battery - this is also why trickle charging won't work for you (I think): it won't charge you battery enough in just one day's time...

Probably you can find more information on the net, or try to find a book in a library on the subject.....
I am not quit sure, but I would guess that you will need a higher voltage solar cell, as the charger basically is limiting the current from the solar cell to the battery - this will take some voltage. Prabably 2 cells of 6 Volt/16 mA in series could do it (they call it 6 V, but the peak V is actually lower, and the real voltage which you will get will still be lower - this  will depend upon where you live - how much sunshine, clouds etc.). Hope this is of some help!
Maarten

I don't actually have the batteries in hand yet as this is a theoretical project so I can't check them, I don't mind paying a bit more for a special battery pack.

There's a 12V 80mA Cell for $10.90, that do the job? This is gunna be used specifically on sunnier days when i'm likely to be out.

[maarten]

You can find a simple charger here: http://www.circuitsonline.net/schakelingen/120/voedingen/simpele-batterijlader.html
Now it is in Dutch, but it is so simple, that you probably will be able to undrstand it. The 317 regulator is in this case used to limit the current - you will see that it is explained in terms of Ohm's formula.
The voltage in for a regulator always needs to be a couple of volts higher than the voltage out you desire (the difference voltage being used by the regulator), I don't know what that exactly would be for a 317 - look it up or just measure it experimentally. If 12 volts in yields you less than 9v out, then you might go for the 6 pack (6 x 1.25 volt = 7.5 v, thus giving you a difference of 12-7.5 = 4.5 volts for the regulator. Probably this is better, as I doubt (as stated before) that you will always get a full 12 volts from the solar cell - maybe somebody else can shed more light on this matter...

[sundgist]

maybe somebody else can shed more light on this matter...

made me chuckle