Can a Resistor Simulate a Light Bulb Load for LED Bulb Installation?

In summary, racers install another set of hand warmers, wired to high, and tape them to the tunnel to keep the system loaded when they remove the bulbs on mod sleds.
  • #1
Mikel_NY
41
0
TL;DR Summary
Snowmobile, shunt regulator needs load to work. Replacing 2- 55 watt bulbs with LEDs

Need to replace draw on system to keep regulator working correct.
Hello All,

I have a snowmobile that uses a shunt type regulator to control voltage. They require a constant load (headlights) to work proper.

The 2 stock bulbs are 55 watts on low with the system running 12v.

Racers install another set of hand warmers, wired to high, and tape them to the tunnel to keep the system loaded when they remove the bulbs on mod sleds.

Is there a resistor I can wire into lighting circuit when I install LED bulbs that will simulate one 55watt light bulb?
 
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  • #2
You need the actual current drawn by the LED bulbs, then the actual voltage with the engine running at cruise speed. Calculate the power drawn by the LED bulbs, subtract from the 110 watts the system is designed for, and the result is the power to dissipate in the resistor. Then calculate the resistance in the resistor.

Sample calculation with made up numbers:
LED bulbs draw 2 amps at 14 volts. That's 2 * 14 = 28 watts.
110 watts total minus 28 watts = 82 watts.
82 watts divided by 14 volts = 5.86 amps.
5.86 amps divided by 14 volts = 0.42 ohms.

These made up numbers need a 0.4 ohm resistor rated for at least 100 watts.
Looking in the Digikey catalog, I find a 0.39 ohm resistor rated for 100 watts: https://www.digikey.com/en/products/detail/te-connectivity-passive-product/HSC100R39J/5587123?s=N4IgjCBcoExaBjKAzAhgGwM4FMA0IB7KAbRADYBOAdhgFYQBdfABwBcoQBlVgJwEsAdgHMQAX3wwADAA560EEkhoseQiRABmCpIAEAWwDyACz2YQ%2BACwbdhk2aYg2HAKoC%2BrA8gCy2VJgCuPNhi%2BAC0cPKKvP6qRJCk9A5OkCBi4iARpAAKBADu2Dw6AErYmHyYrAQ89qJAA. This is not the only power resistor in that catalog, it is just the one that I found in a quick search. This is not the only supplier, there are others just as good that may have a better selection. You will need to do your own calculation with real numbers.

Study the datasheet VERY carefully. That resistor will only dissipate 100 watts with an adequate heat sink. You might be better off to look for a 200 watt resistor, or a pair of 0.84 ohm 100 watt resistors in parallel.
 
  • #3
Thank you, I will look at power draw for my LEDs and follow your formula above to find the correct one for me.
 

1. How do you simulate a light bulb load?

To simulate a light bulb load, you can use a resistor with a value that matches the power rating of the light bulb. This will create a similar load and allow you to test and measure the circuit's performance.

2. Why is it important to simulate a light bulb load?

Simulating a light bulb load is important because it allows you to accurately test and measure the performance of a circuit before connecting a real light bulb. This can help identify any potential issues or failures in the circuit and ensure its efficiency.

3. What is the purpose of simulating a light bulb load?

The purpose of simulating a light bulb load is to mimic the behavior and characteristics of a real light bulb in a circuit. This allows for accurate testing and analysis of the circuit's performance without the risk of damaging a real light bulb.

4. Can any resistor be used to simulate a light bulb load?

No, it is important to choose a resistor with a value that matches the power rating of the light bulb you are trying to simulate. Using a resistor with a lower or higher value can result in inaccurate readings and potentially damage the circuit.

5. Are there any other methods for simulating a light bulb load?

Yes, you can also use a variable resistor or a combination of resistors to simulate a light bulb load. This allows for more flexibility in adjusting the load and can provide a closer simulation to the actual behavior of a light bulb in a circuit.

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