Rigid Industries- Real technology!
Much has come up lately about heat sinks and how they relate to LED lights, output and lifetime. We’d like to spend some time discussing the technology in our products and why we do what we do.
Let’s start with a bit of background information to sort out all the info floating around the internet. Just remember, if you read it on the internet it must be true. Yes, he is a French model “Bonjour”!
Myth #1: LED’s run cool and don’t require additional cooling. While this is true compared to a halogen/quartz or HID it’s still important to manage the heat. Todays ultrahigh power LED’s still produce close to 85% of the input power as heat that needs to be adequately managed. The difference is, an HID is happy at 250f or higher, a hot LED’s cause a short life and more importantly, less output. An LED at 140f will be 20% brighter than an LED at 180f. Cooler LED’s are brighter!
Myth #2: Copper is a better heat sink material. Looking at it from a pure textbook view, yes copper is better. Unfortunately there is more to it, the entire system needs to be designed correctly to take advantage of premium materials(copper or silver). Just because a portion of a larger cooling system is copper or silver doesn’t help LED’s last longer or stay brighter if the heat isn’t dissipated. A properly design LED fixture will transfer that heat energy to the surrounding air or water depending on the light application.
Rigid Industries has invested heavily in not only software based simulation but both lab and real world testing. An LED fixture needs to be designed and tested to ensure the COMPLETE system works together. Using state of the art computer simulation Rigid Industries can create and mold the ideal heat sink shape, taking into account material and airflow consideration using simulated fluid(airflow) dynamics. This all takes place prior to ever even creating a prototype.
Even the best heat sink in the world will only dissipate as much heat as the surrounding atmosphere can absorb. Since 95% of where we operate lights is in air, it makes sense to use Aluminum as a heat sink. Air doesn’t have enough thermal transfer potential of exotic materials(copper) unless exposed to sustained airflow over 1000 linear feet per minute(about 10mph). Material needs to be selected considering many different factors. When selecting material, thermal transfer, manufacturability, cost, weight and durability all come into play. When selecting material, a good rule of thumb is that anything less than 5mph(what happens when your car stops?), aluminum has the advantage in dissipating heat. If the heat sink gets too hot, to quick it will become a single thermal mass and the fins will start heating between one another.
These consideration need to be taken into account when designing the entire system. Just because a portion of the system is copper doesn’t make a difference. It all comes down to transferring that energy to the surrounding atmosphere. If you have an aluminum heat sink, you should have an aluminum circuit board. If one part of a cooling system is working harder than the other then it just gets backed up. Imagine a fire hose that flows through a garden hose to get out. Same thing with heat sink design, the entire system needs to work together with similar heat transfer properties. With similar materials, heat transfer will happen equally and at a constant rate. Once that is achieved you don’t need interface material between the section. More often than not interface material will act as an insulator. In extreme cases, this can cause a Copper PCB to overheat faster since it can’t get heat into the aluminum heat sink. What’s this all mean? A correctly designed heat sink system will give brighter, longer lasting lights.
Now that we have discussed system material considerations, let’s talk about size and arrangement! Heat sink arrangement and size plays an even larger role in sustained output and life of a product. If you can’t get the heat out, then you’ll never get the light output. The best heat sinks have a very basic fin design. Heat rises, give it somewhere to go! Vertical fins are the best, airflow or no airflow. The picture to the left is looking down at the top of our Dually D2. All vertical fins, that is the perfect layout. You can see in the picture below, we keep the surface area high, but still promoting heat to rise. Led housings need to be designed to cool both with no airflow and airflow.
Size does matter! The heat sink above is a heat sink we use with at most 40w of input power(usually 20-35w). That works out to almost 3sq. Inches of surface area per watt of power worst case scenario. We have seen competitors try and convince consumers that less than 1in2 per watt is enough. Is pretty basic physics, the more surface area the better. Keep the light as cool as possible! If the LED’s get hot, they aren’t as bright and don’t last as long.
Design becomes more difficult in bars with extruded housings since the fins have to be sideways. As you can see in the picture, our SR housing was designed to cool with and without airflow. The heat can rise, but once the air starts flowing there are no sharp edges to disrupt airflow and hamper cooling. Think about the way an aircraft wing works. Smooth, fast airflow keeps lights bright, longer, no matter the operating condition. Rigid Industries strives to ensure there are no edges to catch heat or disrupt airflow across the surface of the heat sink.
We could go into how high and low pressure areas are created, causing air to flow from the ends. Really it all comes down to the fact that the Engineering team at Rigid Industries uses THE best technology and resources available to design and manufacture the absolute best products on the market. When you buy a Rigid Industries light, you know that the team in AZ is making sure you get the best performing and best value product possible.
But what happens if the heat sink gets packed with mud, or a jacket laid over it. All Rigid Industries lights have microprocessor controlled thermal protection circuits. The difference between ours and everybody else, is the profile. Most imitators will use analog technology. What that means is the lights start dimming immediately. Rigid uses proprietary digital analysis to keep the output higher longer. When you pair that technology with our leading edge heat sinks, be confident knowing your customers lights will stay brighter longer and still never get damaged even if the user try’s to!
Once all this is done and we get a new light. It’s time to test it. We could spend a whole page on all the testing we do on our lights. But since this is about cooling, we should talk about our chamber! Rigid Industries has an in house Blue M temp chamber that allows us to qualify our light from -75 to 200C! When we say our lights and harnesses are rated from -40 to 150f, you know we have actually tested them! Ask to see any other vehicle company’s temp testing data and see what they come up with. Just because each material is ok to those extremes, doesn’t mean they’ll work together at those extremes.