# Solar power backed circuit to light 1W LED

What I have achieved so far:

Referring https://www.instructables.com/id/BUILD-A-NOCTURNAL-SOLAR-LIGHT-BULB/ , I have successfully built the solar garden light circuit to light a 5mm LED using QX5252F. I am using a solar panel to charge 1.2V NiMh battery during day time and at dusk LED comes up automatically.

What I am looking for:

1. Can I use the same circuit to light a 1W superbright led? If no, what changes are needed to the existing circuit to achieve the goal?
2. If the current design is of no use to light a 1W LED, can you please suggest another circuit to achieve my goal?

If your 1W LED is a single white LED with a voltage around 3V, it will work in place of any other white LED. If it's made up of several LEDs in series, then it probably won't. Check the voltage rating specified by the manufacturer/seller.

However, don't assume that you will get the full 1W from your circuit. 1W would require nearly 1A from the battery, which would drain it very quickly. The circuit will be limiting the current to less than that.

• Thanks Simon for the quick reply. I will try as you advised. – Amol Joshi Sep 17 '19 at 7:35
• Hi Simon. Using 33 micro Henry inductor in the circuit I got 1W while/blue LED to glow enough. Thanks. – Amol Joshi Oct 7 '19 at 9:35

A 5mm White LED draws 15 ~20mA @3V or 45mW ~60mW.

Your Solar panel is 2V 40mA = 80 mW max

Thus you 1W/50mW =20x bigger power LED all components, Solar Cell, & battery Ah capacity need to be increased by 20x

• Hi Sunny. Thanks for the calculations. What worries me now, can QX5252F bear 20X increased voltage in the circuit. As per datasheet it does not, so I may have to look for another driver. – Amol Joshi Sep 17 '19 at 7:38
• Voltage is the same but current demand changes everything – Tony Stewart Sunnyskyguy EE75 Sep 17 '19 at 8:49

Using 33uH inductor in the circuit, LED can draw 110mA current. This is the not full power required to get full brightness of 1W LED but 110mA gave good light.

Thus, 1W LED works with QX5252F in the solar garden light circuit.

This thread can be closed now.

• You can "close" the thread by accepting your own answer. – JRE Oct 7 '19 at 13:39