Silent Echo

So... Got it all installed and it worked great! Keyword: Worked.

One of the 40A fuses soldered itself into the terminals. Upon calling Ron Francis, Chris helped me diagnose the issue. My alternator is too weak. Anyone happen to know the stock alternator output? The controller is trying to draw 80Amps on high speed, but my alternator can't keep up and is frying the board. Ron Francis is sending me a new unit, but I need to upgrade my alternator. If my alternator only puts out 75A, then I imagine a 150A alternator would be plenty.

MGD

Anyone wanna explain to me how having LESS available current caused overheating and damage like that?

From where I stand, it's a faulty controller. Now you know why I only advocate a proper variable speed controller.

MGD

Silent Echo

Come on man, no need to bash what I have. Many other people have used this controller, with no issues. I'm willing to deal with this, and their customer support is top notch.

What is the stock alternator output? I'm not finding any solid answers

MGD

I'm not bashing anything - I'm pointing out the discrepencies I see - that is all.

Ask them to answer my question. Further - since they supply these things they should already know what yer output is. DCC certainly does.

MGD

fltdriver

Stock should be 60amp. but like you are assuming that isn't your problem, your problem lies in the fact that the mark vii draws upwards of 80amp to kick on, at best that controller is only good for 30 amps per speed, 60 if somehow it uses both section to control the high speed (which I highly doubt). I tried to tell you that for the mark vii fan you need dual relays for just the high speed, with 40amp fuses for each relay; both run in parallel. Along with a separate relay/fuse for the low speed setting.

Silent Echo

The controller is rated at 70 amps and recommended by several people on this forum. Talking to their tech support, this controller is often used for this fan. 2 relays in parallel. Thank you for the response on the alternator. 60A is super low, will be upgrading shortly

Silent Echo

Alright. I went to a local alternator shop and had them measure the current that runs through my fan at high speed.
Low speed: 10A
High Speed: 25A

Seeing those currents, even IF I have the wrong fan, I do not believe that the Mark VIII fan is remotely capable of pulling 80A. Ever.

This particular shop does electrical work and harnesses for race engines. The most amperage they have ever seen a fan pull is 35A. And that fan was so powerful, I you stood in front of the grill it would pull your shirt forward. This company, Action Alternators and Starters, has been in business since '85, and they have never seen a fan pull more than 35A.

Most starters pull 90A when cranking an engine, and they are running 4 gauge wire. I doubt a stock fan would have even a 6 gauge wire.

My Ron Francis controller is rated for 70A max with the two relays in parallel. So the controller can definitely handle it. I believe I received a faulty controller, but I will find out for sure when I get the new one back.

I'm upgrading my alternator to a 3G 130A alternator with plugs. Out the door I will be paying $175 for everything. Pretty dang good price for that alternator with all the help they are giving me.

1990 5.0

Its not so much the current the fan pulls while it runs, it's the initial in rush of current that the fan draws when it first begins to turn that probably blew your controller. Others have mentioned this in above comments.

Silent Echo

How do you go about detecting the initial start-up of the fan? Can a tool that measures amperage catch the spike upon start-up?

fltdriver

Yes, using an analog voltmeter that is already setup when the fan is initially turned on can catch the initial burst of power. Something like a digital multimeter probably won't be able to get the reading on it as it will change too fast, you will just get a screen full of dropping numbers.