Continue to Site

Welcome to our site!

Electro Tech is an online community (with over 170,000 members) who enjoy talking about and building electronic circuits, projects and gadgets. To participate you need to register. Registration is free. Click here to register now.

  • Welcome to our site! Electro Tech is an online community (with over 170,000 members) who enjoy talking about and building electronic circuits, projects and gadgets. To participate you need to register. Registration is free. Click here to register now.

capacitor size for headlight issue

Status
Not open for further replies.

blackhemi4x4

New Member
Hi, here is what I have going on here...

I have a retrofitted HID setup in my 2011 Jeep that uses a CANBUS electrical system

My ballast run between 9-14 volts and is 50 watts, so roughly 4 amps?

The canbus system every 30 minutes to an hour will cut power from the low beam circuit briefly, about 1/8 of a second. This causes a super brief flicker of my headlights.

What I want to do is run a capacitor between the ballast and headlight output plug that plugs into the ballast. I need to find a capacitor that will fill this gap of no power.

Im I going the right direction with this or is there a better route I should try?

Thanks
 
First off, why does it cut power from the headlights? A capacitor might help but it really depends on exactly how long the gap is as to the size you'll need. The type of caps designed for car audio system power buffering should work as long as the pulse isn't too long, they're about the size of a modestly sized soda bottle. You might want to shop around for them though as they tend to be massively over priced like anything to do with audio =)
 
Last edited:
Not really sure, but 2006 and later jeep/chrysler/dodge started to use a canbus electrical system that they heavily modified. The very slight power cut off is most likely a way of them doing some sort of system check. Its common on these things. I would say no more than a 8th of a second which is not noticeable when running halogens but super noticeable with a ballast.

With my current setup, im using a relay to get power directly from the battery and it uses the headlight output for signal. I may just use my parking lights as for signal. I dont think I will want one of those large audio sized things under my hood lol.

I guess I can just get my signal from the actual headlight switch so it just bypasses the modules for the headlights. (i really miss simple 12v autos, you can just wire what you want with not issues!)
 
If they are the true HID type bulbs the power between the ballast and the bulb is high frequency AC not DC and is above your vehicles normal electrical system voltages.

Most HID bulbs use a multi KV pulse to ignite them as well.

Your best bet is to buffer the 12 volt source thats tells them to turn on before the ballast not after it. A diode and a thousand uf capacitor may be all you need if the pilot signal current is small.

Just a guess at this point.
 
I would assume, not sure how to tell, the pilot current is small now. It use to pull about 3 amps when the stock 35 watt halogens were there. Now, those connectors just provide 12v to the relay then the relay provides the power to the ballast. Not sure how much current a relay draws.

So, I now realized I described my setup wrong at first. oops. I would want the capacitor to be between the signal output for the headlights and the relay. Pretty much keeping the relay running the ballast during the brief loss of power.

I know my ballast are DC in and the output is somewhere around 30-50k volts. not sure if its AC/DC. There is a firing sequence that is built into the ballast for starting the HID bulbs and if not shielded, it messes with radios, tire pressure monitoring, and other frequencies.

Im willing to try a 1000 uf cap and diode setup depending on the relay current.
 
A 1000uf, 25 volt cap across the relay coil would probably keep the coil from dropping out during the canbus episodes.
Kinarfi
Where are you at?
 
Last edited:
A 1000uf, 25 volt cap across the relay coil would probably keep the coil from dropping out during the canbus episodes.
Kinarfi
Where are you at?

Im in Loganville GA. I actually lived in West Valley City, then Ogden for a couple years 7 or so years ago. I miss it!
 
did you try that, did it fix it?
 
did you try that, did it fix it?
 
Radio Shack will bilk you on price and many don't even carry dicretes anymore, Digikey, Mouser, Jameco and others online are better places to source components.
 
That sir, is truly a unique ballast. A ballast is a coil to limit current. Ballasts pass DC with little or no loss, (coil resistance only). Therefore they run on AC. Now if it's a ballast resistor as in old ignition systems that's a whole 'nuther matter. Do other vehicles with similar lights do the same thing? I don't think I've ever observed your symptoms, and I've been blinded by more than one improperly installed HID system. What does the manufacturer say? As for relocating your power source; what leads you to believe the pulse is not there as well? I would also ASSUME (and you know what that means) that holding this signal hi, may cause an issue with the monitoring circuit. To avoid this, you might consider installing a second relay in series with your headlight relay. This SECOND relay could be a delay type, meaning it doesn't drop out for a predetermined period of time. You know, sort of like delay off headlights. Just do a search for "delay relay" you should be able to find something easy.
 
A ballast is a coil to limit current. Ballasts pass DC with little or no loss, (coil resistance only). Therefore they run on AC. Now if it's a ballast resistor as in old ignition systems that's a whole 'nuther matter.

Actually the term Ballast when referring to a lighting power supply system is a rather generalized term and can include most any form of converter, switching power supply, magnetic device or combination of that takes any type of electrical power input AC or DC at any voltage and regulates it to operate an arc tube type lighting fixture.
 
Status
Not open for further replies.

Latest threads

New Articles From Microcontroller Tips

Back
Top