what would be the best way to connect a battery to about 10 LED lights?

Question

I have about 9-12 LED lights that are 2.1 volts with a max of 3 volts. I also have a 9v battery. I want to know hwo I can maximize the number of lights to the 9v battery with out over charging the lights. I was thinking of putting 2 sierise of 4 lights or 3 serise of 4 ligths in a parallel order. Is that the way to go?

Answer 1

3 groups in series with all the lights in each group in parallel.

Answer 2

To maximize the number of LED you have to take the lower limit of the votage range of the LED (2.1V)

9 V = 2.1*n

n = 4.3, say 4 LEDS in series. Making it find will put the voltage across each LED below the mininum voltage rating.

4 LEDS in series will have a voltage drop of 9/4 = 2.25 volts across each. That's acceptable.

So if we make 4 groups of LEDS in series, with each group composed of 3 LEDS in parallel (voltage across parallel resistances are equal) you'll end up with 12 LEDS all in all.

Now there's a catch here. You can put as many LEDS as you want in each parallel group and the voltage across them will still be 2.25V. So you can use as much LED as you like in 4 parallel group connected in series. Your problem is whether your power supply can give that power. If you supply the power rating of each led and the power rating of your power supply, we can compute for the maximum number of LEDs that you can use.