dual bright leds

I don't know if this will help or not, or how much it has to do with brightness per say, but for determining the resistor values for a particular led use this simple formula:

supply V -  led V / I led

So for example if you were doing a setup where fluctations were not a concern....

supply would be 12...led v would be 2...12 - 2 = 10. So you would divide 10 by the current and get the proper resistor value.

With bulk leds the voltage and current ratings should be given upon purchase or labeled on the package/box they come in.

This formula works for us when using 2v bulk leds for switches etc, things like that used inside the car.  However if you use a higher voltage number for supply (let's say 16) you would get a higher resistor. This would prolong the life of the led but at the expense of some brightness. The greater the resistance, obviosly the less the brightness, but the more current will be limited extending the life.

The regulator seems to make sense for tailights, safety and reliabitly are a major factor.

Good luck with it.

Yes you will depending on the voltage of the regulator.

You did the calculations for 16, 15 and 14.8 volts but if the regulator(s) lets say are 5 volts, you will need to recalculate for that taking brightness levels into consideration as well.

Instead of going through all that..just connect the tach wire. Heres how...

06 Ford heavy duty tach:

Notes: On diesel vehicles the tach wire is lt. GREEN / WHITE in a 5 wire harness held up with white tape behind the parking brake release.

Can also use the DEI 454T tach signal generator.

I don't know..it depends on if it's a 5 volt regulator or not. I was just using 5v as an example.

another thing to take in to consideration if you werent' aware. You mentioned you will wire some leds in parallel some in series.

Now the leds that are wired in parallel will share the same voltage but use more total current. what I would do is on all the leds in parallel use a resistor on each one. With the leds wired in series, the voltage will divide but current will remain the same (the current has nowhere else to go (branch) in a series circuit. what you can do for those is add up the voltage of each led you use in each series array and apply that to the formula I posted, and use just one resistor. As you link each LED in series each will recieve less voltage as you add more so in turn will require a lower value resistor in proportion

If you wire enough leds in series you may not even need a resistor..too many and they might never be bright enough. so as you see there are quite a few factors to consider. Hard to give specific values for anything really until you have everything you need along with all of it's ratings, and THEN start to experiment and take it from there.