Relays and Euro lights

Bernie Benz b.m.benz at
Tue Jun 4 08:07:32 EDT 2002

Simple.  If I were unfortunate enough to live in Chicago, I'd put the relay
package in a plastic bag, just like Audi does with the ECU to protect it
from those that can't keep their drain holes clean.


> From: Chris Covington <malth at>
> Date: Tue, 4 Jun 2002 09:50:24 -0400 (EDT)
> To: Bernie Benz <b.m.benz at>
> Cc: QSHIPQ at, 200q20V mailing list <200q20v at>
> Subject: Re: Relays and Euro lights
> But Bernie, pin configuration aside, you're missing an important factor -
> weather - when you're saying certain in-hood relays work fine for you in
> your dry, (warm?), non-salted-road, Western climate (of course they
> would!) and that they should for Scott as well in his cold, wet,
> road-salted Chicago climate.
> You have more margin for error from Mother Nature, where Scott doesn't.  I
> think weather has more to do with it than the amount of pins in the
> relays.
> Chris
> '91 200q20v
> On Tue, 4 Jun 2002, Bernie Benz wrote:
>> Welcome back, Scott.  Good to hear from you.
>> Sounds like you need to use better relays, or move from Chicago.  A 4 pin
>> relay is not the best choice for this high current, two relay application,
>> IMO.  Bosch and PB make a 5 pin cube relay specifically for this type app.
>> in which there is a common input to two sets of 30A NO contacts and dual
>> outputs, thus dividing the current between two sets of contacts and output
>> terminals.  This has great wiring advantages in that only one #12 wire need
>> go into each socket connector.  In your enviroment maybe the relay cover
>> needs to be replaced with a little silicone caulk.
>> In my 44s I've had my dual relays mounted on the frame member just behind
>> the pass headlight, near where the jump post used to be (it's now airborne).
>> No heat, no corrosion, no fuses, no problems, and wiring runs are as short
>> as possible.  In the 89 chassis they are mounted on top of the pass strut
>> tower.
>> Bernie
>>> From: QSHIPQ at
>>> Date: Tue, 4 Jun 2002 08:34:00 EDT
>>> To: b.m.benz at, brianl at
>>> Cc: 200q20v at, urq at
>>> Subject: Re: Relays and Euro lights
>>> --
>>> [ Picked text/plain from multipart/alternative ]
>>> Just read this one....  The case of "new" spec vs element exposed reality.
>>> The problem with relays is they have a life, specifically, they have a half
>>> life.  The harsher the environment they operate in, the shorter the half
>>> life.  In the case of my "underhood" installed relays in my urq for
>>> instance,
>>> the crap wiring job from alt to relays located them right beside the
>>> radiator
>>> (heat and water/salt).  Which reduced the half life of my relays to less
>>> than
>>> two months.  When these pups get hot and/or wet, there is no guarantee of
>>> spec.  In fact, in my case '83 urq, the relays would randomly arc closed,
>>> this is *with* a 30 amp inline fuse (then run the battery down).  This
>>> wouldn't happen if it was sunny, pretty much a guarantee if it was
>>> raining/snowing (after shut down the lights would either stay on, or the
>>> heat
>>> buildup would turn them on in the middle of the night)
>>> I put up with this for 4 changes of relays in 6 months, until I recently
>>> moved and properly mounted them in the glovebox area, and strung 10/12guage
>>> wire from the battery.  Nary a problem since.  The problem with applying
>>> 200amps relays is a couple fold.  IF your relays are marginal (not new) you
>>> DO risk the chance of not only arcing them, but welding them closed AND
>>> blowing the bulbs out.  I'm only sharing BTDT.  I assure you Bernie, I have
>>> and understand  the operating specifications of *new* 12v 4pin relays.
>>> I'm only sharing what I see in practice, and personal experience.  If you
>>> routinely replace your relays *before* failure, your theory/specification
>>> applies.  IME, few routinely replace relays before failure.  In the land of
>>> winter salt, underhood relays fail quite regularly, so do those high amp
>>> unprotected connections between relay and wiring.  Mounting them near the
>>> battery post means you put them near the hottest heat generator too (turbo),
>>> which means half life ain't great.
>>> "Don't fix if it ain't broke" - ok, but when it does, "Fix it right the
>>> first
>>> time" (?)
>>> My .02
>>> Scott Justusson
>>> practical relay install specialist
>>> In a message dated 5/31/02 3:20:11 PM Central Daylight Time,
>>> b.m.benz at writes:
>>> Do you normally jump start your car with the headlites on?  200 amps will
>>> flow through a discharged battery with an applied voltage at the jump
>>> terminal of less than, or very little more than the normal system opperating
>>> voltage, and rapid chargers are voltage regulated, restricting the peak
>>> applied voltage to about 15 volts.  They are designed to be idiot proof!
>>> Further, the arc over voltage of an open relay is well in excess of 600
>>> volts.
>>> Bernie
>>> _______________________________________________
>>> 200q20v mailing list
>>> 200q20v at
>> _______________________________________________
>> 200q20v mailing list
>> 200q20v at

More information about the 200q20v mailing list