Not long ago we did an article where we swapped the factory turn signals for LED turn signals, which required the use of a load equalizer. Being that we were on a budget at the time, we picked up a 2-amp ceramic resistor-style load equalizer for pretty cheap, but found-after the fact-that this type load equalizer generates a lot of heat, so we decided to swap out the cheapo load equalizer for a Load Equalizer III from Badlands Motorcycle Products.
The Load Equalizer III module works with Harley-Davidson models with or without security systems and is compatible with virtually any of the custom turn signals available and can be used with either Halogen or LEDs, too. This new module produces no heat and is also intended for the '91-later standard turn signal modules. After trying to wrap our heads around the science behind this technology, we asked Dan, aka the Scientist, over at Badlands Motorcycle Products to help us understand more about this technology. And since he described it so eloquently to us, we'll just let it come straight from the horse's mouth.
The differences between the Load Equalizer III and a 2-amp (roughly 6 Ohms) ceramic resistor... Let me try to explain this, while also explaining a bit about the reason for a load equalizer in the first place.
Let's start with the terminology: Technically even the resistor device is "solid state." Solid state actually is only a contrast to "gas state," as in old gas tubes. A resistor is "solid," not gaseous, as are the components in the Load Equalizer III. Really the only things I'm aware of anymore that use gas tube technology are high-end guitar amps. Just about all modern electronics are solid state. So while our Load Equalizer III is "solid state," it is actually a lot more than that, as contrasted with just a resistor. More about that in a bit...
A resistor is the simplest electronic device there is. It is in essence just a piece of wire. You could make a resistor of any value simply by connecting to both ends of a sufficiently long piece of wire. A resistor does just what its name implies; it "resists" the flow of electricity through it. The value of the resistor is measured in "Ohms."
An incandescent light bulb is a special kind of resistor. Once warmed up, it has a specific value of resistance, depending on its wattage value. As we know from Ohm's Law, which is the fundamental basis of all electrical and electronic activities, the electrical current, which flows through a resistor is directly proportional to the voltage applied to the resistor, and inversely proportional to the resistance. This is commonly expressed as V = i * R, where V is the voltage, i is the current measured in Amps, and R is the resistance. Using simple algebra, we can also see that R = V / i. So, if we know the voltage applied to the bulb, and we know the current it draws, we can solve for the equivalent resistance value of the bulb.
When the light bulb is replaced with an LED, the current flowing through the system DRAMATICALLY changes. A typical 1156 light bulb draws roughly 2.5 Amps, while a replacement LED assembly might only draw 100 milli-Amps, or 1/10th of an Amp. This is 25 times less current! So what's the problem? Less current means less power, all should be good... Well, it would be IF it wasn't for the Harley Turn Signal Module (TSM) or other flashing device. The TSM (and other flashing devices) sense the amount of current flowing through the system, and when they see a significantly lowered current value, they think a light bulb has burned out. In the case of the latest TSMs (the security system TSSMs and HFSMs), it sets a trouble code and initiates rapid flashing to alert the rider to change his bulb. Since the LED draws SO MUCH less current than a bulb, the TSM sees it the same as a burned out bulb.
The resistor devices simply "tack on" to the turn signal system in parallel with the LED, and supply a resistance value to make the total current draw roughly the same as the original light bulb. (Remember the Ohm's Law discussion above? This is how we know what value resistor to use.) What's wrong with this? It would seem all is back to the original state and would be good. Well, the problem is that we have not gained any power benefit! We are still drawing just as much current as ever, and we are burning it up in a resistor just like before. BUT... In the original case, the power is being burned up inside the light bulb. Have you ever grabbed a light bulb that has been on for a while? They get HOT!! And this is just the heat that comes through the space inside the bulb to the glass shell from the GLOWING WHITE HOT incandescent filament. In the case of a resistor tacked on with an LED, JUST AS MUCH power is being dissipated and it is in DIRECT CONTACT with whatever touches it. Now, the body of the resistor is considerably more massive, so it doesn't get AS hot as an incandescent filament, but it still gets PLENTY HOTTT!!! I personally don't want this burning away under my butt! And if there is a fault in the system, or if the turn signals are left on for extended periods (4-ways flashing away during a parade, Patriot Guard, emergency on the side of the road, etc.), the resistor will get DANGEROUSLY HOT, to the point of smoking or even igniting into flame!
OK, so how does the Load Equalizer III get around this? By taking advantage of modern silicon (i.e "solid state") electronic switching circuitry. Badlands also takes advantage of how the TSM senses the current flow. The TSM doesn't have to see current flow "all the time" in order to stay happy. It only needs to see it when it is looking for it. So, we give current to it, but only when it wants to see it. How exactly do we do this? Well, that's classified... (In your best Tom Cruise voice say "I could tell ya, but then I'd have to kill ya.") The simple way to look at it is that the Load Equalizer III draws power in sufficient amount to trick the TSM, but doesn't waste any more. So, we are consuming MUCH LESS power than a resistor, and consequently we don't get hot! The bike's charging system also now has to supply much less power for the lights, which gives it more margin to keep the battery up, power other add-on devices (GPS, high power stereo, whatever) or just to not drive it so hard and let it last longer!