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I believe i have found an inexpensive relay sourced locally in the USA, but I need to know if someone (likely Stef?) knows if the relay has a built in diode, as is usually the case for relays to handle the inductive kickback when the relay opens. If i can get this answer, i believe i can provide the part number and source for an inexpensive solution. Anyone?
 

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Hi, the voltage peak happens when the relay closes actually, called flywheel or flyback, and happens towards the device that operates the relay. It is caused by the electromagnetic coil when power is released ;) . Relays usually have a build in resistor to limit this voltage peak, not a diode because a diode makes the relay polarity sensitive and if polarity is reversed, it will destroy instantly the coil.
Stef - you are correct about the kickback, but it happens when the relay opens - the stored energy in the relay coil ( an inductor) is released and opposes the change in voltage through it (dv/dt in engineering parlance). In any case, a diode clamp is the most common to clamp this, but the relay is available with a resistor, diode, or nothing. So your experience is that the F430 relays have a resistor? I want to make sure i choose the right solution and not cause any $$ damage to the car. Thanks much.
 

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Sorry, I indeed inverted open vs closed, you're right, it happens of course when the power of the coil is released. On the F430, all relays have resistors. Ideal solution is a bidrectionnal TVS as a voltage clamp.
The relay that meets all of the electrical requirements (30 Amp, 12V, resistor) and physical requirements is available from www.digikey.com. It is part number A11ASQ12VDC1.2R. The single piece price is $1.46, a "bit cheaper" than what was discussed above. And shipping is available by USPS which is only a few dollars more. I have ordered one for my F430 and I will let you know my results.
 

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I found this discussion very useful, but IMO there was no closure as far as I can tell. As I am an F430 owner and an electrical/electronic engineer, I’d like to try and wrap this discussion clarifying some of the items discussed and provide a recommended solution.

There was an earlier discussion by a poster that indicated he was using the state of the plug in stab to determine whether or not to replace the relays. This is incorrect. For a simple review, relays are mechanical devices that use small amounts of current to control large amounts of current - the former through an electromagnet coil which moves large contacts to control the later. What this discussion properly identified is that after 15+ years of operation, the relays wear, and in particular in two areas. First, the armature that supports the high power contacts will weaken, and second the contacts will burn from arcing. The contacts burn because the voltage in our cars is DC, not AC, so the arc that forms when the contacts open will last until the air gap between the contacts no longer can sustain the arc. The weakened armature slows the opening of the contacts, which exacerbates the time of arcing, increasing the damage. Attached below is a photo from my car of the two contact points in a high power relay that controls one of the radiator cooling fans:

244529
244530

As you can see, there is a burn spot in the center of each contact. This burn spot is the place where the high current passes through the contacts, and it represents a resistance in the current path, reducing the voltage to the load. This is the failure that requires relay replacement. If the plug in contacts on the relay where it seats in the panel are overheating, a more serious problem exists in the plug in panel. Replacing the relay will not effect this issue.

So replacing the relays is definitely recommended, as you can’t see the contacts unless you destroy the relay with a cutting tool, and after 15 years it is almost certain many of them are damaged. I also do not recommend replacing the relays with cheap Chinese products like you can find on-line. Fortunately, you don’t have to. I have researched the proper Bosch relays for the F430, and was able to find a supplier who provides all the Bosch relays listed for replacement for $60 plus shipping. No Ferrari tax! The company is RMEUROPEAN.COM and here is a list of the F430 relays and their Bosch replacement. Simple installation took me about an hour (make sure you disconnect the battery!) – the only challenge was the fan relays which require removing part of the frunk liner to reach.

[table]
[TR]
[TD]PSR7, AR1 and AR2 SPST 30A[/TD]

[TD]https://www.rmeuropean.com/Products/0025421119-MFG14.asp[/TD]
[/TR]
[TR]
[TD]PSR4 and 5 SPDT 30A[/TD]

[TD]BMW Multi Purpose Relay (5-Prong) (Black) 61316919113 - BOSCH[/TD]
[/TR]
[TR]
[TD]N006 X2 (50A) SPST for Fans[/TD]

[TD]Mercedes-Benz Secondary Air Injection Pump Relay (4-Prong) (Black) 002542261928 - HELLA (rmeuropean.com)[/TD]
[/TR]
[TR]
[TD]PSR 8,9, 10 and PDR 8,9,10 SPST 30A[/TD]

[TD]Mercedes-Benz Horn Relay (4-Prong) (Black) 0025421119 - BOSCH[/TD]
[/TR]
[/table]

Note the photo below of the PSR7 etc. relay – it has gold plated contacts which are excellent for corrosion protection, which the original relays did not have - an additional benefit of the replacement relays:
244531


Post installation, in my car the water and oil temperature each ran one division lower. I am guessing that replacing the fan relays increased their speed and hence their cooling efficiency.
 

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As an electronics engineer, i can comfortably tell you that nothing is more reliable than a mechanical relay, as long as you replace them (as noted in my discussion) after 14+ years of labor as the contacts will pit. The electronic version will never be as robust. The usual electrical transients, environmental extremes, and mechanical shock that they experience in an automotive environment are all bad for electronics. Cheap solution as noted is simply to replace the relays proactively. Simple job, cheap, and no downside potential. Great reliability improvement, and leaves the car as designed.
 

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er, Steph van certainly uses solid state in his products and they are orders of magnitude reliable !
Seems to me this thread went a bit off course. It was originally about replacing the plug in mini-relays, which is what I was discussing. Stef's products are in boxes which I'm sure are well engineered to address the issues I raised - I have the pump relay from him in my F430. But there is a dongle that plugs into the relay socket. Hence Stef's solution is NOT a plug replacement for a mini-relay as we have been discussing.
 

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I think I must respectfully disagree, NASA, and the aerospace industry, et all , certainly use electronic relays w/ great success! I had a professor tell me electronic components are 100X more reliable than mechanical ! ones ! no need for antediluvian thinking unless one really wants to be a purist ! ( which you close w/ ) I think we should avail ourselves of the wonderful , proven technology that is continually developed !
Our cars will be better for it !
would you have us still use lead acid SLI batteries ? in our cars when lithium ( 2nd and 3rd generation ) is uber safe ,40-50 POUNDS less weight , and reliable .?
As I mentioned above, I agree that properly designed solid state switching devices in the long run will likely be more reliable than a mechanical device. However, this thread was about replacing the mini-relays in the F430 and there are, at least to my knowledge, no plug in solid-state replacement for same with the required power capacity. The $3 Bosch replacement relay that has worked for ~14 years will likely last at least another 14 years and that is a very cost effective and simple preventive upgrade (which I also did to my F430).
 

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As I said before, a $60 replacement and an hour or so of work makes your F430 the same as factory built. I showed what the relay contacts look like in my 26K mile car so I replaced the relays.
 

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As i noted in my earlier post, RMEUROPEAN.COM has the relays and they are still very inexpensive. The part numbers are listed in the post.
 
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