I have 9V 3W solar panel. I would like it that during the day sunlight it will charge a battery and will provide 9V for the circuit. when Night comes the circuit will take is power from the battery (that was charged during the day). Is the above possible? how can I achieve that?
What sort of 9V battery do you have in mind, and why?
My project is mainly an audio circuit that will produce sound. it needs to run on 9V. I might use an arduino for generating some random voltage to effect some parts in the audio circuit. This is why I ask for charging 9V and not 5V battery
Probably not. Please post a link or circuit diagram.
12V is a better option, because you can use readily available 12V gel cells, with reasonable capacity to driver speakers, etc. "12V" solar panels (18V peak, in fact, so you could use two of your 9V panels in series instead) and charge controllers are also readily available, and cheap.
No, it is not possible. The 9 volt solar panel is OPEN CIRCUIT voltage of 9 volts. IF you put any load on the panel, it must output less than 9 volts. Therefore it cannot charge a 9 volt battery. Also a 9 new 9 volt battery has more than 9 volts on the terminals.
Your solar panel might charge a set of 4 c cells in series. BUT in all cases you need a charge controller to stop the battery from discharging into the solar panel when a cloud passes between the sun and the panel. The controller also stops the battery from becoming OVERCHARGED.
Example. My driveway gates are powered by two 12 volt storage batteries in parallel. They are kept charged by a 22 volt solar panel using a charge controller.
Assuming two constant variables - my 9V 3W panel and the audio circuit I posted; What can I do in order to make it work during night time and not only at sunlight?
Can I make the solar panel to only charge the battery and that the battery will deliver power for the circuit? if so - what battery and battery charger I need to use?
Thanks
There is nothing you can do with a 9 volt solar panel to charge a 9 volt battery. Get a 12 volt panel and proper charge controller.
The circuit does not require 9V, and in particular, the audio amplifier chip is rated at up to 15V.
That is a very strange circuit! It seems overly complex for the audio signal that it generates. Can you take a moment to explain?
this is a video of how the audio circuit might sound like. you say I can also power it from lower voltage?
The posted circuit should operate on any voltage between about 2V and 15V. Where did you find it?
The multivibrator on the left side will generate an 8 second pulse about once every 75 seconds, assuming that R34 and R33 are 10 Megohms, rather than 10 milliohms as shown on the diagram. How might that be useful?
Are you sure about that, because I count 18 cells.
Those solar panel voltages are AFAIK always stated under rated load with full noon sun.
Open voltage of a 9volt panel should be about 12volt.
The rechargeable 9volt batteries I have used were AFAIK 7C NiMH.
Leo..
Of course the sales link show NO data at all, except price and stuff to catch the eye of a passing buyer.
Always count the cells, and knowing a cell is about 0.65volt open and about 0.5volt under ideal load, you can then calculate panel voltage. If you know dimension of the panel, then you also can estimate panel power. I never had false voltage/current information for those resin-coated panels, but current will drop over time because the resin starts to get cloudy after two years.
Leo..
Interesting. I did not know about that.
Tomorrow I need to put out my solar panel battery charger to top up the tractor battery and will count the cells, if I can determine what is a cell and what is not. And it does have a proper charge control unit. MY company built it many years ago. Uses PWM, if I remember the technician correctly.
Note that some panels could use two cells in parallel.
A 16 volt panel could have 32 cells or 64 cells.
Leo..
Yes - R33 and R34 are 10Mega ohms . this circuit is imitating a call of birds in the morning and I rewrite the schematic from that pcb trace
Got the PV panel out and checked the voltages.
The panel is 12 cells across and 6 rows, so 60 cells. Each cell is 2-3 inches square. No clue about connection pattern.
Panel voltage with no charger connection to battery is 21.69 volts.
Panel voltage while charging the battery varies around 17.9 volts.
Output of charge controller is 14.85+- and continuously varies. Probably until battery is fully charged.
Must be a 30-cell (two parallel) panel.
15.3volt max power point at 25degrees C, assuming 0.51volt per cell.
Leo..
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