led resister values 4.5V to 24 v
- Thread starter RJ2
- Start date
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mudman cj
Flashlight Enthusiast
You can use LED PRo 2.12 to help with the calculations.
Because the LEDs in those lights are typically wired in parallel, directly driven off of the batteries which are in series, you effectively have a Vf of a single LED, or about 3.5V. This works because the actual voltage of the batteries under load sags just enough to limit the current to these levels.
If you wire lights in series with each other, you can have no more than 6 lights before the Vf exceeds the 24 supply, so this is one limitation. So, you could have 3 groups of 6 in series with each group in parallel with the others to use 18 of the lights. These would each need about a 85 to 135 Ohm resistor depending upon the actual Vf of the LEDs used (assuming 3.5 to 3.2V Vf respectively). The remaining 4 lights would be another serial string also in parallel with the other 3 strings of 6. 4 lights in series would need about 286 to 320 Ohms, again depending upon Vf of the LEDs with the same assumptions as before to generate those numbers.
The total current draw of this setup would be 35mA x 9 x 4 strings in parallel = 1.26 Amps.
Because the LEDs in those lights are typically wired in parallel, directly driven off of the batteries which are in series, you effectively have a Vf of a single LED, or about 3.5V. This works because the actual voltage of the batteries under load sags just enough to limit the current to these levels.
If you wire lights in series with each other, you can have no more than 6 lights before the Vf exceeds the 24 supply, so this is one limitation. So, you could have 3 groups of 6 in series with each group in parallel with the others to use 18 of the lights. These would each need about a 85 to 135 Ohm resistor depending upon the actual Vf of the LEDs used (assuming 3.5 to 3.2V Vf respectively). The remaining 4 lights would be another serial string also in parallel with the other 3 strings of 6. 4 lights in series would need about 286 to 320 Ohms, again depending upon Vf of the LEDs with the same assumptions as before to generate those numbers.
The total current draw of this setup would be 35mA x 9 x 4 strings in parallel = 1.26 Amps.
