How to Choose the Right Diode Size for Your Off-Road Lights | Expert Tips

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In summary, a forum user is seeking help in determining the appropriate size diode for wiring off-road lights on a vehicle. The lights are LED and rated at 18W each, drawing less than 1A. The user has found a selection guide for 2A Schottky rectifier diodes and is considering using a larger diode, such as 5A or 10A, for added safety. Other users recommend using one diode per light and doubling or tripling the rating to account for potential voltage fluctuations.
  • #1
Mike1220
Hey guys, brand new to the forum and have an electrical questions or you guys. I can work my way around wiring but only the basics, I tried to do a search but with my knowledge I came up empty handed
So here's the background

I'm trying to find what diode size my buddy needs for his truck,
He has some off-road light pods that he wants to wire into his OEM fog light feed so they will turn on automatically during the day and when he hits his high beams, but he also wants to run them on a separate switch so they can turn on with another small bar he has upfront.
We are trying to prevent one feed from backfeeding to the other, such as the fog circuit backfeeding to the wire harness and possibly frying something

The lights are very low power since they are LEDs, only draw 1AMP each if that I believe

Can anyone help me to figure out what size diode we need to allow enough power to flow to the lights?
This is on a vehicle so it's all a 12V system

Any help is VERY much appreciated!
Thanks in advance
- Mike
 
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  • #2
Need to know total current. You said 1 Amp each but not how many light there are.
 
  • #4
CWatters said:
Need to know total current. You said 1 Amp each but not how many light there are.

My apologizes, didn't realize I forgot to mention that, there will be 4 pods total, 2 per diode. Or would 1 per diode be better?
The lights are rated at 18W each

berkeman said:
And once you have the total current, you can use a browser like this one at Digikey to start making your selection. I'd be inclined to use a Schottky rectifier diode for this application, to minimize the forward voltage loss through the diode... :smile:

http://www.digikey.com/product-sear...es-rectifiers-single/1376383?k=schottky diode

.

Thanks! I'll check it out [emoji106][emoji106]
 
  • #5
Mike1220 said:
there will be 4 pods total, 2 per diode. Or would 1 per diode be better?
If you can use one diode per light, that will let you use lower current diodes, and spread the heat dissipated out more.
Mike1220 said:
The lights are rated at 18W each
That's more than 1A per light. 18W/12V = 1.5A, so in looking through the Digikey selection guide, you should probably be looking at 2A Schottky rectifier diodes...
 
  • #7
I'd double or triple the rating just because. The cost is about the same. Maybe even 10A

This is a car, and things happen. Voltage can go to 15V, owner can buy more powerful bulbs, etc.
 
  • #8
berkeman said:
If you can use one diode per light, that will let you use lower current diodes, and spread the heat dissipated out more.

That's more than 1A per light. 18W/12V = 1.5A, so in looking through the Digikey selection guide, you should probably be looking at 2A Schottky rectifier diodes...

The lights are LEDs, not sure if that makes a difference. The specs said they draw less than 1A, but then again, can't always believe everything you hear on the internet I guess haha

berkeman said:
Here's the selection guide with filters applied for 2A Schottky Rectifier Diodes in through-hole style (instead of surface mount style):

http://www.digikey.com/product-sear...t=0&page=1&quantity=0&ptm=0&fid=0&pageSize=25

:smile:

Yes that's the kind id rather forward to him! Whatever will be easiest to put inline with the wiring.
So any of those Diodes would work?
But I guess I should mention the same question I am asking meBigGuy, which is should I go with a bigger diode just to be safe? Such as a 5A or 10A just to make sure that the diode is powerful enough to not have any issues? There are fuses elsewhere in the wiring to protect the battery and any other circuitry that matters like the OEM computers

meBigGuy said:
I'd double or triple the rating just because. The cost is about the same. Maybe even 10A

This is a car, and things happen. Voltage can go to 15V, owner can buy more powerful bulbs, etc.

So might it be best to go with say a 5A or even a 10A diode instead of a 2A just to be safe?
 

1. How do I calculate the right diode size for my off-road lights?

To calculate the right diode size for your off-road lights, you will need to consider the voltage and current requirements of your lights. First, determine the voltage that your lights require and then divide it by the current of the diode. This will give you the minimum diode size that can handle the load of your lights.

2. What is the importance of choosing the right diode size for off-road lights?

Choosing the right diode size for your off-road lights is crucial as it ensures that the diode can handle the electrical load of your lights without burning out. It also helps in preventing any damage to your lights and the vehicle's electrical system. A correctly sized diode will also ensure that your lights function efficiently and have a longer lifespan.

3. Can I use a larger diode than the recommended size for my off-road lights?

No, it is not recommended to use a larger diode than the recommended size for your off-road lights. A larger diode may be able to handle the load of your lights, but it can also cause overheating and damage to your lights and the vehicle's electrical system. It is best to stick with the recommended diode size for optimal performance and safety.

4. Are there any specific diode sizes that are better for off-road lights?

There is no one specific diode size that is better for off-road lights. The diode size you choose will depend on the voltage and current requirements of your lights. However, it is recommended to choose a diode with a slightly higher current rating than your lights to ensure it can handle any fluctuations in the electrical load.

5. What are some common mistakes to avoid when choosing a diode size for off-road lights?

One common mistake to avoid is choosing a diode with a lower current rating than your lights require. This can cause the diode to burn out and potentially damage your lights and vehicle's electrical system. Another mistake is not considering the voltage drop across the diode, which can affect the overall performance of your lights. It is also essential to ensure that the diode is properly installed and secured to prevent any electrical issues.

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