"N" led hitch cover

[surroundsound64]

It took a bit of time soldering all of the LEDs up. I ended up with an odd count so I had to add a resistor into the equation.

How did you wire them? I can't really tell with that camera angle... did you do sets of them in series, then all the sets in parallel, the last set being the set that had to use the resistor?

[Mikeski]

They are wired in series, 6 at a time, then the groups are wired in parallel. The LEDs are rated for 2.2 volts so this works well up to 13.2 volts, above that I am starting to push them so I might add a few loops of small gauge wire to induce a little voltage drop. The last group only had 4 LEDs so I had to add a resistor to drop the voltage to that group.

I finally received my LED order from China (actually where 99% of LEDs originate). Now I have a bunch of 5mm 5000mcd (they are bright!) LEDs in Red, Orange, and Blue plus some super bright 5mm White 10000mcd LEDs. I will be using the white ones as backup lights and in my cupholders. I am actually a little concerned about using them in the cupholders because they are so bright, I might need to switch to the Blue ones.

[jroyal]

They are wired in series, 6 at a time, then the groups are wired in parallel.

Isn't this a series-parallel?

[jroyal]

Also, what is a bright for 5mm in UV (ultraviolet?)

[Mikeski]

The concept is correct, four in series works for white or blue LEDs. Most Red, Orange, or Yellow LEDs need to have 6 or 7 in series. Technically UV LEDs are not visible so none are bright? However I notice most LED sellers incorrectly show purple LEDs as UV. LEDs are rated in mcd which I believe is the acronym for milli-candela. Generally 5000mcd is referred to as "superbright LED". It is difficult to look directly at a 5000mcd LED without hurting your eyes. These are readily available for reasonable prices so there is no reason not to use them. You can always run them at a lower voltage if you find them too bright, it's easier to reduce the output of a bright instead of increase a dim one.

Electrically speaking you can just wire the LEDs in series to split the voltage down to the desired level:

V(led) = V(source)/number of LEDs

You can also use this equation to determine the resistor needed:

[V(source) - V (led)] / I (led) = R

V (led) and I (led) should be obtained from your LED supplier.


There is also the old trial and error method. Single LED resistors will fall in the 300-600 ohm range on 12-14v systems. Just try different ones until you get what you like. Leave it hooked up for a couple hours, it it gets hot or starts to loose it's punch then you are pushing too much current, increase the resistor value.

[surroundsound64]

How are you going to wire them into the vehicle's lighting system? Or, where are you going to tie it in?