[urq] High beams/Relays... sigh.
Mike Sylvester
mike at urq20v.com
Thu Jun 28 04:36:17 PDT 2012
Scott,
I think he has a bad ground.
There must be a common grounding point (relay coil and something else)
that is bad and is sitting at something higher than 0V from path to 12V
through something else that is connected to the same point. When the
relay is in backwards there is a voltage at the relay with current path
to ground the wrong way through the coil an then the indicator light.
Just enough current to activate the relay. Fix the ground and the
backwards relay will not stick.
Mike
> -------- Original Message --------
> Subject: Re: [urq] High beams/Relays... sigh.
> From: Scott Justusson <qshipq at aol.com>
> Date: Thu, June 28, 2012 12:45 am
> To: djdawson2 at aol.com, urq at audifans.com
>
>
> Not full of crap, only the possible wrong conclusion? How bout some Napkins? Here's how a Bosch/Hella single reverse-bias diode works. First let's look at a properly hooked up (Pin 86 12v+/Pin 85 12v-) Hella/Bosch single reverse-bias diode relay
> http://forums.audiworld.com/picture.php?albumid=166697&pictureid=236800
> If you look at C, when switched on, all current flows through the relay coil because the diode blocks current flow through the other parallel path. If you look at D, switching off your high beams, you get a back EMF load in the opposing polarity. The diode 'gate' is now open, and the load becomes the actual suppression device (in the form of heating the coil for milliseconds), as apposed to the headlight switch contacts (Note: NOT the pin 30>87 contacts, they have nothing to do with this phenom)
>
> Now, let's take a look at an improper hooked up (Pin 85 12v+/Pin 86 12v-) Hella/Bosch single reverse-bias diode relay
> http://forums.audiworld.com/picture.php?albumid=166697&pictureid=236801
> If you look at A, when switched on, current flows through both the coil and the relay, the relay will function normally. If you look at B, this is where the trouble starts. With the sudden switching off, you get the same back EMF load reverse polarity, but now the diode is blocking that spike. In the common 1N4001 (standard relay diode app), the Peak Inverse Voltage spike is ~50volts, so chances are good that diode won't last very long until failure. The EMF voltage will now bleed to the headlight switch just before release, and to the board mount (in an electronic circuit).
>
> What happens when the diode blows in a euro light conversion application? Nothing. Because it's hooked in parallel, so it's the exact same thing as a non polarized, non diode equipped relay that is used more commonly on the exact same application. And those of us with non-diode equipped relays running for the last 20 years on our euro-lights installs without a relay or a switch failure can attest that diode doesn't really do anything in a Automotive lighting application.
>
> So..... What I'm trying to understand is how a diode equipped relay hooked in reverse then, can cause relay sticking. I claim whatever is going on, the installed *diode* can't cause that, because it's not a possible diode function. And further, in 'failure' mode, the circuit will operate like any other non diode relay. And, it's possible I have this very wrong too.....
>
> My apologies in advance to a certain rocket scientist I know out your way, who uses really cool visio programs to draw his circuits, where I prefer the napkin/marker method.....
>
>
> Cheers
>
> SJ
>
>
>
>
>
> -----Original Message-----
> From: djdawson2 <djdawson2 at aol.com>
> To: urq <urq at audifans.com>
> Sent: Wed, Jun 27, 2012 8:04 pm
> Subject: Re: [urq] High beams/Relays... sigh.
>
>
> Hmmm... I'll do my best to not take this personally, but seems to me that you're
> telling me I'm full of crap.
>
> My car:
> 1) 4 brand new Bosch 30 amp relays.
> 2) Perfectly functioning headlight switch prior to installation.
> 3) Completed installation resulted in one of my high beams "sticking" on, dash
> indicator did as well.
> 4) Searched internet, found article claiming that reversed polarity on a diode
> equipped relay could cause relay to remain closed. Can't comment on the
> validity of this claim, nor can I find it when searching now. I do not have a
> PhD in electrical engineering.
> 5) Switched 85 and 86 wires on affected light's relay.
> 6) Problem solved - NO new stalk installed.
>
> This is a simple statement of fact... it happened on my car.
>
> Initially I believed that there somehow must be voltage remaining between 85 and
> 86. There, in fact, was about 2 volts present (high beams off).
>
> Want me to video this phenom when I get home?
>
>
>
>
>
>
>
> -----Original Message-----
> From: Scott Justusson <qshipq at aol.com>
> To: mike <mike at urq20v.com>; djdawson2 <djdawson2 at aol.com>; spotatashleys
> <spotatashleys at hotmail.com>; s.b.mills <s.b.mills at gmail.com>; urq
> <urq at audifans.com>
> Sent: Wed, Jun 27, 2012 9:03 am
> Subject: Re: [urq] High beam indicator stuck on, high beam stalk has no effect-
> what did I break?
>
>
> I agree Mike! I have not seen nor heard of a diode affecting 30>87 activation
> in any way, as that's not the purpose/function of the reverse-bias diode.
> Further, although the voltage spike is suppressed, the amperage spike is much
> less 2amps, which is hardly enough to arc weld the points, if they were even
> involved. Or looked at another way, if the amperage was too high, the coil
> windings would weld themselves together, pretty much eliminating the magnet
> function of the relay.
>
> I say a reverse-bias diode really doesn't do much for a light circuit, nor most
> others basic switched Automotive applications for that matter. The diode
> protects electronics/switches of components attached to Pin 85 and Pin 86. It
> is not there for protection of the 30>87 jump.
>
> >From what I read on the internetses, there is more misinformation on what a
> reverse-bias diode equipped relay does, and what it's designed to do. It's been
> a while since I got trained on them for entry system design, but I don't see a
> big advantage to them in most Automotive applications. I've run non-diode
> Hella/Bosch relays for years on lights and aux components, and any failures I've
> seen of a 'relay' itself, has nothing to do with, nor would it be 'avoided' by,
> putting diode in the relay.
>
> So much mis-information I read on forums, I was half-tempted to draw out what a
> reverse-bias diode install does in a relay.... From many reads, I bet almost
> half of the reverse-bias diodes are already blown, and the relay is functioning
> just fine.
>
> And btw, I *know* the light switch on the car in question is the problem within
> the first mile of the night-time drive of Steve's car.....
>
> Thanks for the sanity check.
>
> Scott J
>
>
>
> -----Original Message-----
> From: Mike Sylvester <mike at urq20v.com>
> To: djdawson2 <djdawson2 at aol.com>; qshipq <qshipq at aol.com>; spotatashleys
> <spotatashleys at hotmail.com>; s.b.mills <s.b.mills at gmail.com>; urq
> <urq at audifans.com>
> Sent: Wed, Jun 27, 2012 6:56 am
> Subject: RE: [urq] High beam indicator stuck on, high beam stalk has no effect-
> what did I break?
>
>
> First of all, Steve doesn't even have a relay in his circuit so in his
> case, the polarity of 85 and 86 is irrelevant.
>
> However, if we want to continue the relay discussion, the wrong polarity
> of across 85 and 86 is not going to cause the relay to stick. For the
> high beams to stay on, there needs to be a current path between 30 and
> 87 or between the positive side of the coil and the load. Its reverse
> polarity is not going to create this current path.
>
> The one schematic that I saw had a diode in series with the coil and one
> parallel. The 2 diodes are in opposite directions. The parallel diode
> is to shunt the back emf when the coil gets de-energized. The series
> diode is to protect the parallel diode from reverse polarity. Due to
> the series diode, if the 85/86 polarity is reversed, the relay will not
> activate when voltage is applied. Even if the relay does not have the
> series diode, a reverse polarity will just cause a lot of current
> through the diode, not create a current path to 87. This high current
> could damage your high beam switch.
>
> Regardless, when the high beam switch is off, there shouldn't be a
> voltage across the coil circuit, so its polarity wouldn't matter. If
> there is a voltage there, your high beam switch is a problem.
>
>
> Mike
>
>
>
>
>
>
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