Switching to LED turn signals offers significant advantages: improved visibility, longer lifespan, and lower energy consumption. However, many vehicles' electrical systems aren't designed for the low current draw of LEDs. This can lead to hyper-flashing (rapid blinking) or even malfunctioning turn signals. This is where load resistors come in. This guide will explain why you need them, how they work, and how to choose the right ones for your vehicle.
Why You Need Load Resistors for LED Turn Signals
Traditional incandescent bulbs have a relatively high electrical resistance. This resistance creates a significant load on the vehicle's electrical system, allowing the turn signal flasher to operate correctly. LEDs, being significantly more energy-efficient, draw much less current. This low current tricks the flasher unit into thinking a bulb is burnt out, resulting in hyper-flashing or complete failure of the turn signal system. Load resistors effectively mimic the resistance of the incandescent bulbs, solving this problem.
How Load Resistors Work
Load resistors are simple electrical components that add resistance to the circuit, thereby increasing the current draw. By introducing this additional resistance, they bring the total current back to a level the flasher unit recognizes as normal. This ensures your turn signals blink at the correct rate. They work by dissipating excess energy as heat—this is why they often need heatsinks.
Choosing the Right Load Resistors
Selecting the appropriate load resistors involves understanding a few key factors:
1. Wattage:
This is crucial. The wattage rating indicates the amount of power the resistor can handle without overheating and potentially failing. A resistor with insufficient wattage will overheat, potentially causing damage to your wiring or even a fire. Always choose a resistor with a wattage rating significantly higher than the calculated power dissipation.
2. Resistance (Ohms):
The resistance value determines the amount of current the resistor will allow to flow. This value must be calculated based on your vehicle's system voltage and the difference in current draw between the original incandescent bulb and the LED replacement. Incorrect resistance will lead to either ineffective hyper-flashing reduction or potential damage to the electrical system.
3. Calculating the Required Resistance and Wattage:
Calculating the necessary resistor value and wattage requires knowing the voltage of your vehicle's system (usually 12V) and the current draw of both your original incandescent bulb and the LED replacement. You can typically find this information on the bulb packaging or your vehicle's owner's manual. Use the following formulas:
- Power (Watts) = Voltage (V) x Current (A)
- Resistance (Ohms) = Voltage (V) / Current (A)
Example: Let's say your incandescent bulb draws 2A, and your LED replacement draws 0.2A. The difference is 1.8A (2A - 0.2A).
- Power Dissipation: 12V * 1.8A = 21.6W. You'd need a resistor rated at least 25W (or higher) to provide a safety margin.
- Resistance: You would need to calculate the resistance required to emulate the load difference. This is complex and varies depending on factors like the flasher unit, so it's often easier to check what value the manufacturer recommends for your specific LEDs and vehicle make/model.
4. Heatsinks:
High-wattage resistors generate significant heat. Using a heatsink is highly recommended, especially for resistors above 10W. A heatsink improves heat dissipation, preventing overheating and extending the lifespan of the resistor.
Installation
Installation generally involves connecting the resistor in parallel with the LED in the turn signal circuit. Always disconnect the battery's negative terminal before working with car electrical systems. Refer to your specific vehicle's wiring diagram for accurate connection points. Consult a qualified mechanic if you are unsure about any aspect of the installation.
Conclusion
Load resistors are a practical solution for preventing hyper-flashing when switching to LED turn signals. Properly selecting and installing these resistors is essential to ensure the safety and longevity of your vehicle's electrical system. Remember to always prioritize safety and consult professional advice when working with electrical components. Incorrect installation can lead to damaged components or even fire hazards.
