I am helping a friend with his headlights on his 04 chevy silverado. He ordered an aftermarket set of HeadLamps that have the halo design around the angel eye projector and the low beam light as well. The original design was rather poor and being a beginner electronics engineer I thought I would attempt to re-wire the fixtures. I did my fair share of research on this particular company's design and found everyone else ordering this specific brand were also having issues with the led lights shorting out. There was a small component box with the epoxy to keep from seeing what the circuit is but from running a few tests I can only determine that it is more than likely just a simple voltage divider. After to much time spent on trying to repair the existing circuit without any luck, I went online and special ordered a pack of 12v 3.5mm water white led lights each pre-fab'd with a 1k resistor, soldered and wrapped and I was sure I was going to be able to wire these in straight to the parking light wires in the truck and fix them permanently to the halo rings and not have another worry about them ... they lasted 3 days before one burnt out then its pair .. now both sets of led lights intended to light the high beam halo rings are burnt out.. I thought from my experience with vehicles that the electrical varies approx. 9 to 14 volts which should be handled without issue according to the specs of the leds I ordered. Is there something I am missing here .. why is this simple dinky little circuit causing me such a headache. someone claimed that with the alternator being 3 phase that it could produce surges of up to 34 volts .. if this is true then what are my next step's in the design? Must I use a linear voltage regulator along with the led lights .. all I want is for the 8 little accent led lights to work properly and I have never had such trouble with my LED lights its very frustrating ...

 

The 1k resistor should have been dissipating ~120mW max. A very small surface mount type buried in wrapping/potting material might overheat and fail, but a properly sized resistor should have survived. Sounds like design/manufacturing done on the cheap.

 

Read a few articles from this search: https://www.google.com/search?clien...channel=fs&q=+littelfuse+tranients+alternator

 

Just addressing a single point: The number of phases in the alternator means (almost) nothing for this problem.
For instance, you would have the same transient voltage problem with a carbon brush type of DC generator from 1950.

 

The auto environment is nasty. The Littlefuse document pretty much confirms that. With ECM's etc in the automobile, you have to transient suppress anyway. The use of three phase increases the ripple frequency making it easier to filter.

Loose connections will do a number on things. For instance a loose battery cable can take out the alternator regulator.

LEDs have a different forward voltage depending mostly on their color. If your rolling your own, you should also math Vf so that they won;t have different intensities. The series string of LEDS has to be below 12 V. 's probably a wise move to add a series diode with a peak reverse voltage of at least 200 V.
Recently, there was a nice discussion on ETO about commercial LED lamps used on a boat that had catastrophic failures when operated on 24 VAC.

It was determined that the SMT diodes were likely inadequate and that there was likely coupling between the 120-24 VAC transformer which would couple some energy from lightning strikes to the system. A small capacitor was recomended for the "SYSTEM" on the 24 VAC side.

 

Read a few articles from this search: https://www.google.com/search?clien...channel=fs&q=+littelfuse+tranients+alternator

This helped tremendously, unfortunately the transmission just crapped out on my buddy's truck so the lights were pushed to the back burner. Do atv's have this kind of transient voltage issue too? Another friend of mine wants RGBs installed on his 4-wheeler.

 

My guess is you're having a heat related failure. How hot are your parts getting?

The battery actually filters a ton of noise. Just an example, but motorcycle alternators (and probably your buddies ATV) often use shunt type regulators, which are very noisy and the bikes often won't even run without a battery installed to filter the noise. Here are some old oscilloscope screen shots from a past project where I tried to kick-start a motorcycle with a shunt type regulator with and without a battery. Notice how bad the noise is:

1 kick, no battery, bike would not start:

1 kick, capacitor connected (similar to a battery), bike did start, notice the reduction in noise:

 

My guess is you're having a heat related failure. How hot are your parts getting?

come to find out it was both. once I installed the new circuit with the littlefuse component, the two halo's around the high beams burnt out still and I already had a feeling before it may be heat related but when the low beam halos ran just fine and still running now it was pretty obvious. Thanks guys for all your help. Love this Web Forum <3