WHY would you do that? How would that solve the problem, or even throw light on it?

 

If the surge is the problem, then I would expect there to be some sort of dampner in the system to absorb it otherwise he'd be blowing other fuses.

I hope that makes sense.

On my race car I have a seperate power point for all my other stuff so this doesnt happen. Mostly nitrous equipment (heater, solenoids, line lock etc) which pulls about 40A on top of all other stuff running in the car.

The fan should have a label of some sort telling you what kind of amp draw it pulls.

 

I see what you're saying.

The surge we were speaking of is the "inrush current" the fan draws when it starts up. It wouldn't cause other circuits to blow, just the one the current is flowing THROUGH, in this case the fuse to the fan motor.

You were probably thinking in terms of a voltage surge at the battery somehow. That would affect everything and if there were any filters in the system, then relocating it might help.

However, the electrical system doesn't have such dampers in it because automotive systems generally don't surge much if at all. The PCM and some other electronics do have some degree of "overvoltage protection".

So I think the misunderstanding was in how you interpreted our language in regard to surge. Probably describing it as "inrush current" would have been better for us to use to make it clear what's happening.

 

Gotcha

Got this from Jusnes site

How many fans are you running? Judging from your post you're only running one.

If it were two, which I would figure would be the most you could fit on the truck, a 30A fuse should be more than enough to cover you.

Also, what exactly killed the controller?

Fire ranger, there are usually empty slots from stuff that the truck wasn't equiped with. All depends on the options, there are usually one or two slots open. On my truck there's one adjacent to some 40 and 50A fuses.

Also Winks, you should try and disconnect it from the battery and hook it up at the "power distribution" point. On my 2k Ranger the cover is behind the dist. box next to the brake booster. You'll see a Ford 125A fuse when you pop it open. I would connect there.

 

My fan is also rated down there, and still draws that high a surge. That is the current drain at speed, not at startup. All DC motors draw high current surges.

In addition, the physical "baffling" of the fan makes a huge difference. A fan which can "talk to itself" because of poor baffling works harder on startup.

Again, hopefully you read my post to understand why your idea of moving the hookup point will help nothing.

No one knows what's destroying these controllers -- but many of them are dying. Mine went and it wasn't even a Jusnes fan -- it was a completely different straight blade design.

I don't think you understand DC motors. They basically look almost like a short circuit at startup, with only the armature, brush and wiring resistance to limit the current.

Once they begin running, the moving armature cutting through the fixed field also acts like a generator, making "back-EMF" or "counter voltage" that increases the effective resistance of the circuit (in simple terms) and drops the current. This effect on a shunt type or PM field motor is what keeps the motor from "running away" -- it's speed is inherently self-limiting.

So all these fans draw quite high current spikes at startup, but most don't draw them long enough to pop the fuse.