How to Wire a LED Light Bar

Truck Accident

Roseburg, Oregon USA - October 16 2012: Police car cruiser LED emergency lights at an accident in front of a shool loading zone

LED Lights

The idea of wiring anything—to a novice—can seem overwhelming. You might find yourself thinking: don’t you need to have electrical knowledge for these pursuits? Or at least some semblance of electrical engineering and understanding of circuitry? While it can certainly be daunting, you should know that you don’t need to be an expert to complete simple wiring and an LED light bar falls into this do-it-yourself category.

So long as you have the right materials and a prompt, you’ll be able to do it. Better yet, when it’s done, you’ll feel like a bit of a wizard. So for those of you that are well-versed in electrical engineering, then this might read like one massive oversimplification. For those of you that have no idea what you’re doing, if you follow this guide, you’ll be able to wire an LED light bar without any difficulty (at least we hope).

The LED

Before we begin our tutorial, it’s important that you know the properties of the equipment you’re working with for your vehicle. Regardless of your vehicle being a car, truck, SUV, off-road vehicle (off-road led light bars), or another type of vehicle, it is crucial to know which types of LED light bars are right for you—and to know how they function and are wired. This knowledge will only help you further understand the science and how the pieces communicate.

LED (light emitting diode) is the light of the future. Before, the standard lighting product was the incandescent light bulb, which had a tendency to drain lots of power and could ultimately burn out. However, LED lights manifest light through a tiny microchip. Electrical current passes through this chip and causes an illumination—and extra heat pours into a built-in heat sink.

This isn’t to say that LED lights last forever but they don’t necessarily break or burnout as incandescent or compact fluorescent light bulbs (CFL). Instead, the chip wanes over time, until the efficacy is no longer what it should be. Due to their intelligent design, they last longer than traditional lighting and can withstand heat to a degree that was once unfeasible before their invention. As an approximation, LED lights have a 50 times longer lifespan than an incandescent light, 25 times longer than halogen, and 10 times longer than CFL.

When it comes to the ‘color’ of the lighting, different phosphor material can convert LED lights to match most light beam glows. They’re often given filters to produce an intended coloring as well. In short: LED lighting products are energy efficient, diverse, resilient, and intelligent. Today, they’re the most recommended light source in the industry, being that they’re cost-efficient, non-temperamental, and withstand intense heat.

Wiring an LED Light

What do I need?

Before we touch on circuitry and the most viable way to wire your LED light bar, the light must be installed. Find more information in our post on installing the LED light bars and LED emergency lights.

First, let’s start with materials. At the bare minimum, you’re going to need a power source, an LED light bar (tailgate light bar, mini light bars, off-road light bar, etc.), and the appropriate cabling. If you’re going to do a proper job with all the bells and whistles, then you’re going to want to buy some high quality resistors too (we’ll touch on what purpose these serve in a moment).

Different light bars provide different functions to a vehicle, and it’s important to pick out the best-fit one for you. A common difference between light bars are the full light bars and visor light bars. It’s helpful to compare the two options and see which one might be right for you.

Regarding the necessary tools, you’ll need some pliers (needle nose and electrical are best), a soldering gun, solder, and electrical tape. Here’s a breakdown:

Materials

  • LED(s)
  • Power source (battery)
  • Cabling (wires)

Tools

  • Soldering Gun
  • Solder
  • Electrical Tape
  • Pliers

While we’re being vague on the exact materials here, we have to generalize because LED lights come in different colors, shapes, and voltages. It’s project-specific. Despite, no matter what sort of LED light bar you’re looking to wire—or the power you want to connect to it—you’re going to need the above materials.

The Standard

Within each LED light there’s going to be two wires; a positive and a negative. These are what we call electrodes. In most LED light bars, the longer wire is going to be positive. Note: this is not always the case and you must first, before any other step, identify the two.

  • The anode is the positive wire
  • The cathode is the negative wire

If you look at your LED light bar, hopefully, you’ll be able to see that within the light itself, the cathode has a wire that points upward (in the bulb) and the anode has a wire that points horizontally (in the bulb). If you’re still worried, you may want to call the manufacturer to discern which is which. Unfortunately, most LED lights bars don’t come with anode and cathode labeling. Both electrodes can look identical.

These wires are then going to connect to the positive and negatives of your power source (battery), and the battery is going to provide voltage (pressure) in a volume that amounts to the voltage of your LED light. The standard current for an LED (this varies dramatically, however) is 20mA — which means 1-5 volts.

Wire Your Battery

Now, once you’ve discerned the voltage necessary, you’ll need to connect your anode and cathode to the positive and negative of the battery. This will need to be done with the soldering gun. While this may seem tricky, there are plenty of DIY videos and tutorials online that explain the ins and outs of basic soldering. It’s a rather simple procedure; you’re heating a material to cover a surface area and when it dries, those two surfaces are bonded.

We want to note here that there are plenty of ways to achieve this connection that doesn’t involve soldering. For the sake of simplicity and efficiency, we’ve decided to use that as our method because in smaller scales it has the best efficacy.

Believe it or not, right here you can be done! If you’ve calculated your voltage correctly and your light has an on-off switch, then the current will flow, and the LED light should power on. This is, without a doubt, the most basic setup.

Power Source → LED Light

Yet, it’s not the best way. Nor is it recommended. You may even find yourself asking, okay… so what if I have twenty LED light bars that I want to wire, does that mean I’ll need a separate battery for each of them? Of course not. But that’s why we’re going to explain series and parallel circuits.

But first, let’s perfect the basic wiring. Onto resistors.

Resistors

This is where a bit of research is involved, and a slight bit more of knowhow. A resistor is essentially a passive device that runs between your battery and unit (the unit here being an LED light). By using resistors, you can manipulate your circuits to have a certain set voltage and current. Essentially, they’re a utility that helps govern the output of the battery. Hook a 9V battery into a light and there you are, it turns on! But, what if that LED can’t support the entire voltage? Pretty soon you’re going to have a scolding hot battery in your hands.

By installing a resistor, you could then say, lower the voltage and current that’s flowing from the battery in so that you’re LED light doesn’t become a campfire. Seems simple, right? It’s simply a dam you’re calibrating to let some water through. Understanding resistors exact value and how it relates to both your battery and your LED light bar is what makes them difficult to use.

This then becomes where a bit more research is involved, as you need to buy the perfect amount of resistors (value) to design your circuit exactly as you want it. Still, they serve an important purpose; essentially they stop things from frying.

Correct Voltage

So after all that resistor talk, you may be wondering what the correct voltage you should be using is. If you use too little, your LED will not power on or will be scant more than a soft glow, but if you supply too much, you’ll burn out the microchip (and perhaps other things). The rule of thumb is to always provide the amount of voltage that matches the capacity of the LED light. Further, it’s advised that you supply a tad under to air on the side of caution. Thus, if you have an LED light that supports 5V, run a current that’s 4.5V.

Test

Once you start to grasp the concept of voltage, current, Ohm’s law, and resistors, you’re going to be able to wire your LED light bar in a variety of different ways. We encourage you to do this, as the more familiar you are with the LED lighting and wiring process, the less complex it becomes, further allowing you to wire more efficiently and at larger scales.

There are tons of calculators online that will help you figure this out, but the base equation for resistors is as follows: r = (v1-v2)/I

In which case:

  • V1 = the voltage of the battery
  • V2 = the voltage of the LED
  • I = the current of the LED

Circuits

As a novice, wiring a proper circuit can be difficult. We recommend you stick to one light initially, master the wiring process there, and then advance. If that’s where you’re at, great. What you should know then is this: there are two primary ways to wire multiple LED lights together; parallel circuit and a series circuit.

Series

Wiring LED lights in series have one great advantage; it’s straightforward. Quite literally, as the circuit is linear. Each LED is connected end to end, cathode to anode, until there are no lights left. Another massive advantage is that voltage flows through the entire circuit—and the amount required is exactly as you’d think (sum of LED voltage).

In which case, you can wire ten 5V LED lights together and that becomes (5V x 5V) 25 volts needed to power your circuit. Being that the voltage is distributed, the same ‘voltage rule’ is at play. Provide just under what is needed. Lastly, when calculating the appropriate value for your resistor you’ll simply use the sum of all voltage as V2. The current remains a constant—you do not add it together.

The important thing to note here when it comes to resistors is that, if you wire them in series, they become the sum (similar to the voltage of all LED lights), but if you wire them in parallel, it becomes resistor/2. Meaning if you have a 10 Ohm resistor next to a 10 Ohm resistor in series, you have a 20 Ohm resistor. In parallel, however, a 10 Ohm resistor beside a 10 Ohm resistor would be a 5 Ohm resistor (10 Ohms/2).

Parallel

The main difference between parallel and series circuits is that a parallel circuit provides the same voltage to each LED, but the current is divided by all parallel LEDs. Unlike a series circuit, when it comes to how to wire an LED light bar, you’re going to connect all anodes and all cathodes together. This means positive to positive and negative to negative.

For an oversimplification, in series, if you have a 12V battery and four 3V LEDs, then it’s going to give each of those LEDs 3 volts. However, in parallel, that battery will give 12 volts to each 3 volt LED, which will obviously burn them out. So what’s the advantage? The advantage here is that your LED light bars can all be powered by a single battery fit to their voltage. That means if you have five 3 volt LED light bars, you’re not going to need a battery that can output 15 volts, rather, only one that needs to power 3 volts.

However, being that it drains more current, a parallel circuit will also deplete your battery quicker than a series circuit would. Lastly, you can’t diversify in a parallel circuit. All LED lights need to have the same voltage and current.

In which case, a simple parallel circuit for an LED light bar would go as follows: three 9 volt LEDs with all anodes and cathodes connected to each other, then connected to a 9v battery. There’s no resistor needed because V1 = V2.

In the case where a resistor is needed, the only difference is in the current. As I = LED current X number of LEDs).

  • V1 = battery voltage
  • V2 = LED voltage
  • I = current x volume of LEDs

Conclusion

We hope this tutorial was simple enough to understand, even for someone with no electrical engineering experience! With the right materials and tools, there’s no reason you shouldn’t be able to wire your LED light bar on your own. The truth is this: when the dynamics are dumbed down, they really aren’t that confusing. By starting with a single LED light bar and expanding from that, you’ll notice the pattern does nothing more than repeat itself.

For more information on wiring an LED light bar, or to purchase LED light bars online, contact us at LED Equipped today.

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