Alternative Fan Wiring -- A Sanity Check, Please...

[Excaliber]

I like the jaunty angle, bloody well done mate.

[patrickt]

Originally Posted by Excaliber

I like the jaunty angle, bloody well done mate.

A beautiful job, if I do say so myself.

[PANAVIA]

So the only things I dont like about circuit breakers is that if they auto-reset sometimes they will continue the burn.

Your new version should be fine, but I would de-couple the pushers and the pullers as previously suggested.

30A is fine for your puller -- but I would separate your pushers with another 30A.

Steve

[RICK LAKE]

patrickt Pat First off the fuse holder you have is good for about 15-20A with low spikes of the curcuit. You get into the 30A spike and above or a 20A draw, you will melt that holder everytime. The problem is the spring in the holder gets hot and loses tension. Over time it cooks, just like yours. Fuseable links are what you need. You can get them pre made at more part stores. You are looking for a 12-14 gauge fuse link for the fans. The guys are right about the front fans. I like the look too but they don't do alot for the cooling. The splitter that came with the car does a better job of making the air spread out and go through the radiator better. The little fans block air flow also at low speeds. Once you get above 40 mph, you don't need coolant fans. A schroud around the primary cooling fan would work better. This will force more air through the radiator.
Steve has it right about curcuit breakers, they work great to protect a curcuit, but if shorted out to a ground, they just keep resetting until either wiring harness is burnt up, grounding spot is no longer in contact, or the component kills the breaker. I have burnt up harnesses running them. This was before I used relays on all large ampage draws.
One side note, You would need a heavyduty amp meter but it is possible that the primary fan is starting to go bad. The could be an worn brush internally and causes a higher amp than normal to engage the motor. I don't know how long these fans last??? My fans are still hooked direct from ERA and the gauge never pinned with all coming on or running. The most should be a quick 30-40 amp surge to the neg side and the Alt should pick this up and cover. I was running a 70a alt. I have gone to a 120a system and replaced the amp meter with a volt meter. I am not a fan of too much ampage being runned through too small studs with plastic insolators for the electrical system. Rick L.

[patrickt]

Originally Posted by RICK LAKE

Fuseable links are what you need.

Now you tell me.

I think the truth of the matter is that my POS Smiths Ammeter gauge just isn't worth a crap when it comes to readings -- and the needle sticks when it goes all the way to the left. I've never blown the 30A fuse on the fan circuit (which is both the pushers and the puller) and, if you can believe the literature, the puller yanks 15 amps and the pushers yank 8 amps. I know I own a clamp-on inductive amp gauge but I believe it's only for AC. I'll check that later today. If it's AC only then I'll trot out and buy a DC one. I'll measure the spike and running loads along the circuit. I'm serious about the Smiths gauges. They look cool, but they're absolutely garbage. My fuel gauge never read right, then it "sprung" apart in the dash, I replaced it, it still didn't read right but read differently than the first one. If the amps on the combined fans are anywhere near the circuit breaker's theshold then what I thought I might do is split the pushers off the fan circuit and route them, only, to the manual override switch on the dash and leave the puller running off the thermostatic switch - separate relay and circuit breaker as well. It really bugs me that the Smiths gauges are such crap. C'mon, how hard is it to make an ammeter gauge anyway?

[RAO-3]

Originally Posted by patrickt

Now you tell me.

I think the truth of the matter is that my POS Smiths Ammeter gauge just isn't worth a crap when it comes to readings -- and the needle sticks when it goes all the way to the left. I've never blown the 30A fuse on the fan circuit (which is both the pushers and the puller) and, if you can believe the literature, the puller yanks 15 amps and the pushers yank 8 amps. I know I own a clamp-on inductive amp gauge but I believe it's only for AC. I'll check that later today. If it's AC only then I'll trot out and buy a DC one. I'll measure the spike and running loads along the circuit. I'm serious about the Smiths gauges. They look cool, but they're absolutely garbage. My fuel gauge never read right, then it "sprung" apart in the dash, I replaced it, it still didn't read right but read differently than the first one. If the amps on the combined fans are anywhere near the circuit breaker's theshold then what I thought I might do is split the pushers off the fan circuit and route them, only, to the manual override switch on the dash and leave the puller running off the thermostatic switch - separate relay and circuit breaker as well. It really bugs me that the Smiths gauges are such crap. C'mon, how hard is it to make an ammeter gauge anyway?

What about going with the circuit breakers that require power to be removed to be reset? This would still kill the power but require you to turn the car off and then back on again before it would reset, allowing you to 'acknowledge the problem' and not necessarily leave you stranded if the fusible link went out. Rick is right about the fuse holders - you need to get one that handles the rated voltage and current to work any application. Circuit breakers and slow blow fuses are for protecting motors and the like as they can deal with the in-rush currents for a short period of time before failing.

Just a thought.

-Ray

[patrickt]

Alright, as a service to the Cobra community, I went out this afternoon and bought a true RMS/CAT III Inductive AC/DC Ammeter. It's accurate to .01A and has the Peak Capture mode to give you the inrush current. After all, I needed one anyway. Here are the readings: The entire fan circuit (meaning both the puller fan and the pusher fans) runs consistently at just under 22 amps with the engine running. With the engine off, and the corresponding voltage drop, amperage goes up to just under 25A. That's pretty much spot on with the written specs, which say that the puller yanks 15A max and the pushers yank 8A max. The momentary inrush current spikes are significantly higher than that -- and the meter can catch some pretty high readings, but they are only momentary spikes and not enough to throw a breaker or burn a fuse.