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Excellent! If you find yourself with even more time on your hands how about a solid state circuit for the heater fan resistor module and also I would love to get rid of those pucks that control the radiator fans. Good work
I have thought about replaceing the fan relay(s) with a Solid-State solution that would let me PWM the fans to any speed. Then the two ceramic "Puck" resistors could be removed entirely.
I didn't realize the heater fan resistor module was an issue. What happens to that thing?
Not in phoenix but ill page butters to the thread, hes close. Any projected price on these? i'll buy one!
I am hesitant to throw a price out there. Volume has a huge impact on that and I simply don't have an idea how many I will sell at this point. That said, I don't think it is going to be too pricey for what it is even in low volumes. But if your expecting it to compete with cheap relays on eBay and Amazon you are going to be disappointed.
But I'd guess the only difference between that and the cheap relay is the printing on the case. Assuming the picture is correct, that relay is also Made in Hungary.
But I'd guess the only difference between that and the cheap relay is the printing on the case. Assuming the picture is correct, that relay is also Made in Hungary.
Unfortunately, an OEM made part is not nessarly same as the OE part supplied to Porsche. With an OE part the manufacturer builds the part to Porsche specification. Porsche cares a lot about reliability so there is incentive to keep the quality high. When an OE supplier decides to make an aftermarket part they no longer have to worry about what Porsche thinks, and are free to do what ever they want. In the case of the OEM Stribel relay, it is highly suspect that it is made in Hungary instead of Germany like the OE relay they produced for Porsche. It very well could be a great relay that is Equivalent to the one they make for Porsche. Or it could be a striped-down ultra-cheap relay that Stribel contracted out to some company in Hungry to save money. Honestly, I don't really know for sure. I might pick up an OE and OEM Strible relay and see what behind the cover...
Honestly, solid state designs being what they are (well, that is when they're not cheap Chinese made crap), the OP could own the market for these things the world over. Of course yes, testing and refinement must be done first
I have thought about replaceing the fan relay(s) with a Solid-State solution that would let me PWM the fans to any speed. Then the two ceramic "Puck" resistors could be removed entirely.
I didn't realize the heater fan resistor module was an issue. What happens to that thing?
PWM solution would be huge, imo those puck resistors and the high current wiring to them is a fire hazard.
On the heater fan module it's the mechanical contacts that cause problems. They get dirty and corroded causing a voltage drop affecting fan speed and eventually the only fan speed you can get is full.
The internal component quality on relays are a crapshoot. If you open a URO relay, the family dog could be trained to make better solder joints than what you'll see in there.
Re: PWM control on fans
In college, my design team used a 944 fan motor for a project and used a TIP120 + PWM to control it at 12v. It sucked 7A at steady state (IIRC, and more than a dozen when transient) and we friend a lot of transistors trying to get it down. We ended up needing a really big heat sink if I recall.
What about making a standalone "relay" that mounts in a well ventilated area?
The internal component quality on relays are a crapshoot. If you open a URO relay, the family dog could be trained to make better solder joints than what you'll see in there.
Re: PWM control on fans
In college, my design team used a 944 fan motor for a project and used a TIP120 + PWM to control it at 12v. It sucked 7A at steady state (IIRC, and more than a dozen when transient) and we friend a lot of transistors trying to get it down. We ended up needing a really big heat sink if I recall.
What about making a standalone "relay" that mounts in a well ventilated area?
As you found out, a BJT transistor makes for a poor high current power control device. Their internal resistance it too high and generate a ton of heat as a result. Newer switching technologies are vastly better. To give you an example, was testing the SSR yesterday at 15A continuously and meshering how hot the switching components where getting. After a a few minuets I put my finger directly on the switching circuit and it was barely getting warm. I then stupidly put my finger on one of the eight 25 Watt load resistors and burned a few layers of skin off. Point being that semiconductor technology has reached a point where heat sinks are becoming unnecessary in a lot cases.
This sounds like a most fantastic idea! I'm definitely in for something that keeps reliability up and keeps a 30+ year old car going! Even for more money, if you're not having to replace crappy ones every so often, it's a good thing!
07-04-2015, 07:04 PM
