I think the solar panel you have mentioned is inadequate. These solar panels are used for 3v button cells. But the LED you mentioned requires atleast 5v source (3.6v forward) with current capacity of 30ma x 7 = 210ma (7 LED's). The panel's current rating is very less-- 50ma. So it will require too much time to charge a battery of 3Ah so that it can run for 12 hrs. Even if you connect 2 panels in series, only voltage will be added up. Current will be same.
For your project, I think either you connect 4 AA batteries in series.
Battery's capacity should be 3Ah | 30ma x 7led x 12hr = 2520mAh => 3000mAh considering efficiency approximately 75%.
Solar panel could be => (2 in series) x (6 sets in parallel) i.e. (6v 50ma) x 6 = 6v 300ma. Or a single 6v 300mA or equivalent.
Thank you for your help.
I have to compromise somewhere as to maintain a design that doesn’t look silly.
I can easily accommodate 4x AA batteries in series. And propose Duracell Supreme Rechargeable 2450mAh AA (or equivalent manufacturer).
I have re-evaluated the LED specification. I am proposing of using four LED an example below:-
https://www.watercoolinguk.co.uk/p/3mm-hyper-bright-LED-white-15000mcd-20-31V_19660.html
Apparently these consume a similar amount of power and give out 10 times the light of the previously specified LEDs:-
Technical details:
Color: White
Material: InGaN
Lens: Water clear
Brightness (in mcd): 15000 max (ultra bright)
Block voltage: typical: 3.1 V, max: 3.4 V
Current draw: 20 ~ 30 mA (130 mA peak)
Beam angle: 20 °
Solder temperature: 260 ° C for 5 seconds
Wavelength: 520nm
The Solar panel is the sticking point for me. I don’t not have a vast amount of room and have found two which hopefully will work out:-
The first one is the smaller of the two and the one I would prefer to use:-
Power Output: ~6V @ 1W (~167 mA) * Output Type: DC Voltage
Dimensions: 4.9 x 2.5 x 0.13 in (125 x 63 x 3.4 mm)
Operating temp range: +32 to +158°F (0 to +70°C)
The second one is slightly larger:-
Output DC voltage : 6V, 1.5W
Output Current : 250mA ( depend on the power of sunlight )
Weight of Solar Panel : ~54g (0.12lbs, 272ct )
Size of Solar Panel : 140 mm X 110 mm X 3 mm / 5.5" X 4"3/16' X 1/8"
Following your calculation:-
30mA * 4 (number of LEDs) * 12 = 1440mAh
Therefore 4 batteries would give me:- 4 x 2450 = 9800mAh
I am then assuming that the batteries (when fully charged) would have enough to drive the LEDs for 12 hours.
But will the Solar panels specified have the ability to recharge the system it 12 hours?
Im assuming to calculate this I multiply the panel output (mA) by the charging time (12 hours) and compare it to the power consumption (less 25% for losses)
If this is the case; the first panel would give 167mA x 12 = 2004mAh * 0.75 = 1503mAh
The second panel would give 250mA x 12 = 3000mAh * 0.75 = 2250mAh
So both potentially could work? Or am I missing something blindingly obvious?
Thank you for your help and please excuse my ignorance, but im quite enjoying learning about all this..