variable voltage causing bulb to fail?
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Tue May 22, 2007 8:21 am quote
I have just heard back from the manufacturer of the autolumination flashing breaker bulb that failed for me. They contend that the bulb was working well, but that the Vespa's variable voltage caused the failure. Does the Vespa have variable voltage? Perhaps someone who knows about such things can educate me.
Molto Verboso
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Tue May 22, 2007 8:29 am quote
Yes, pretty much every vehicle that produces electricity from an engine has varying voltage, it just depends on how good the alternator and regulator are at controlling that swing. A fully charged battery can have a voltage around 12 to 12.5 volts. A vehicle while idling can put out around 12.5 to 13+ volts. At speed vehicles can put out 13 to 14+ volts. The "optimal" voltage for most automotive manufactures is ~13.5 volts while the engine is running. So a typical swing could be 12 to 14.5 volts, but I'm not too familiar (yet) with how much Vespa/Piaggio scooters' voltage swings given hot/cold full battery or almost dead battery and RPM.

A LED shouldn't die because of voltage swings, the control unit for that LED could fail though. Ask them what voltage range they designed their bulbs to work in, no production vehicle out there will stay at a fixed voltage. The good aftermarket product companies should make their products functional in at least the 11 to 15 volt range.

Edit: I work on automotive OEM electronics, and they give us operating voltage ranges in the specs. The range can even be 9.5 to 16 volts for normal operation (but audio amps will obviously have less output as the voltage goes down). Critical components will have an even bigger range.

Last edited by Andrew on Tue May 22, 2007 8:39 am; edited 2 times in total
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Tue May 22, 2007 8:37 am quote
LEDs are much more susceptible to variable voltage (mostly the high spikes) than a normal bulb. That said, all 12v vehicles charge at ~14v so the bulb has to work well from ~12v to ~14v. This is an average voltage output and rectifier/regulators don't always remove the spikes.

To test if this is the problem you'd have to connect an oscilloscope up and look at the wave form over a range of RPMs. If you get a nice smooth line that moves between 12-14v then they are full of it. If you get spikes over 16v they may have something.

"good LED bulbs" would have a current regulator built into them.
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Tue May 22, 2007 8:40 am quote
Andrew wrote:
Ask them what voltage range they designed their bulbs to work in, no production vehicle out there will stay at a fixed voltage. The good aftermarket product companies should make their products functional in at least the 11 to 15 volt range.
Thanks Andrew! I emailed autolumination back and asked for that information. Once I hear back, I'll let other know what they said.
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Tue May 22, 2007 8:51 am quote
oopsclunkthud wrote:
LEDs are much more susceptible to variable voltage (mostly the high spikes) than a normal bulb. That said, all 12v vehicles charge at ~14v so the bulb has to work well from ~12v to ~14v. This is an average voltage output and rectifier/regulators don't always remove the spikes.

To test if this is the problem you'd have to connect an oscilloscope up and look at the wave form over a range of RPMs. If you get a nice smooth line that moves between 12-14v then they are full of it. If you get spikes over 16v they may have something.

"good LED bulbs" would have a current regulator built into them.
Thats true, the spikes can be the killers, by "swing" I meant no, or very small, spikes. Good designs can/should handle "normal" spikes though. And good point on the oscilloscope, some people would just use a multimeter which won't show you any of the details that matter.
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Tue May 22, 2007 10:17 am quote
I have heard back now from autolumination about the braker bulb and voltage range. This is what was provided in their email to me:
Quote:
All leds have the same tolerance: 12 - 14.5 volts

Standard automotive batteries are 12 volt, but frequently their range can be as high as 16 volts.

There are several causes of voltage related failures on leds. Some vehicles chronically cause premature led failures. This is normally related to excess voltage, voltage spikes, or high levels of AC current being generated from the alternator. While glass bulbs are slow to react to rapid surges, leds can be destroyed in milliseconds from a sudden spike or chronic high voltage, or excessive AC current from an alternator that has one or more burned out diodes. We have a new led protector that can be spliced into the + wire to protect against minor voltage surges. These work great in vehicles that have high voltage, or are prone to voltage surges. They can also help protect the leds from:

1. Switching on the ignition & starting the engine.

2. Changing or disconnecting the battery.

3. Charging the battery with an auxiliary battery charger, or revving the engine hard with a weak or dead battery.

4. Using jumper cables.
They are offering a load equalizer that can be spliced into the positive wire to "even out" the voltage being passed to the bulb. I ordered one ($1.99), and they are replacing my failed bulb. Once I give it a whirl, I will finish the write up I am doing on this product and will post in the Review section.
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Tue May 22, 2007 10:36 am quote
They should just build it into the bulb, it's just a capacitor. $1.99 is not too much but if it takes up too much space it will be a problem.
Molto Verboso
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Tue May 22, 2007 10:45 am quote
oopsclunkthud wrote:
They should just build it into the bulb, it's just a capacitor.
Yeah, no kidding... some companies cheap out the wrong parts. If they are charging $1.99 for the cap then it would definitely have been worth at their cost it to just build it into the product from the beginning. The sales/marketing team I work with get frustrated with me (an engineer) for similar ideas.
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Tue May 22, 2007 11:11 am quote
oopsclunkthud wrote:
They should just build it into the bulb, it's just a capacitor. $1.99 is not too much but if it takes up too much space it will be a problem.
It looks like you just splice it into the line.

I will need to spend some time trying to figure out where best to do the splice, but the device itself looks pretty simple (from the photo).
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Tue May 22, 2007 11:17 am quote
harnadem wrote:
oopsclunkthud wrote:
They should just build it into the bulb, it's just a capacitor. $1.99 is not too much but if it takes up too much space it will be a problem.
It looks like you just splice it into the line.

I will need to spend some time trying to figure out where best to do the splice, but the device itself looks pretty simple (from the photo).
With those you just cut the wire (that you are going inline with) and insert an end into each of the blue plastic and press down on the metal "fork" it splices the casing and makes contact, then flip the tab over to protect from coming apart and shorting. They aren't the most reliable method for a vehicle (vibration and bumps), but they do work. I personally would cut, strip, twist/braid, solder and heat shrink the connections. But those connectors should suffice.
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Mon Jun 04, 2007 8:00 am quote
Any update on this one? I'm wondering if it might answer my Hyper-Lite problem - see my post in projects. At this point, the lights are on full bright all the time... no more brake light flashing and no dual intensity... just on full all the time.
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Mon Jun 04, 2007 8:13 am quote
Re: variable voltage causing bulb to fail?
harnadem wrote:
I have just heard back from the manufacturer of the autolumination flashing breaker bulb that failed for me.
Hmm. Mine just died, too. It worked fine in January when I put the scooter to sleep in the barn, and was stuck in a non-flashing "brake" mode when I fired it up in May. The whole scooter has about 200 miles on it. There can be no more than 50 miles on the Autolumination Braker unit. I was pretty happy with this as a brake light modulator solution until now. I was just about to get one for the Ducati, since it uses the same bulb as the Vespa.
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Mon Jun 04, 2007 8:22 am quote
gromitdaddy wrote:
Any update on this one? I'm wondering if it might answer my Hyper-Lite problem - see my post in projects. At this point, the lights are on full bright all the time... no more brake light flashing and no dual intensity... just on full all the time.
That was one of the problems that I was having. Last week I received a replacement bulb, and the load equalizer. I'm in the process of trying to figure out which of the four wires in the tail light works the brake light. Once I have identified it, I plan on installing the equalizer and replacing the bulb. Then the fun starts!
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Mon Jun 04, 2007 8:29 am quote
Thanks. Please keep us posted!
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Mon Jun 04, 2007 11:09 am quote
Clearing-up a few concepts...
Our auto-scooter Vespa's alternator circuit is reasonably clean, being full-wave rectified and well regulated. The problem is our CDI ignition introduces spurious energy into our electrical system. The LEDs are not being affected. Instead, the LEDs control circuit is being damaged (due to the low noise immunity of it's design). The voltage suppressor being offered (@ a reasonable $1.99) is not a capacitor. If it were, wiring it in series with the brake light would render the brake light permanently off (a capacitor doesn't pass DC). I hope this explaination helps you in understanding the nature of the problem.
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Mon Jun 04, 2007 12:24 pm quote
Re: Clearing-up a few concepts...
addicted wrote:
The voltage suppressor being offered (@ a reasonable $1.99) is not a capacitor. If it were, wiring it in series with the brake light would render the brake light permanently off (a capacitor doesn't pass DC). I hope this explaination helps you in understanding the nature of the problem.
Like he said, it's not a capacitor but an inductor. Simply a wire wound around a ferrite, they resist changes to current and look like a short at DC but offer higher resistance at higher frequencies (to cancel out noise or spikes).

'nothing like a little discreet component functionality in an integrated circuit world!
Molto Verboso
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Mon Jun 04, 2007 12:29 pm quote
Re: Clearing-up a few concepts...
lomunchi wrote:
'nothing like a little discreet component functionality in an integrated circuit world!
True.
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Tue Jun 05, 2007 6:26 am quote
Re: Clearing-up a few concepts...
lomunchi wrote:
addicted wrote:
The voltage suppressor being offered (@ a reasonable $1.99) is not a capacitor. If it were, wiring it in series with the brake light would render the brake light permanently off (a capacitor doesn't pass DC). I hope this explaination helps you in understanding the nature of the problem.
Like he said, it's not a capacitor but an inductor. Simply a wire wound around a ferrite, they resist changes to current and look like a short at DC but offer higher resistance at higher frequencies (to cancel out noise or spikes).

'nothing like a little discreet component functionality in an integrated circuit world!
Right. I understand the nature of the problem. My question is would it likely work to protect the controller witch now appears to be dead? The LED's themselves clearly work. I can replace the controller, but don't want to if the new one would fail die to the same problem.
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