Excessive Amperage Broke My Fan !?

[Optikon]

Its an engine not a computer chasis... There is ~ a foot of room behind the fan.

EDIT: What do you mean protection ? It has a FUSE... What kind of protection are you looking for? Some sort of Overvoltage-proof-submerible-analog-to-digital-driven-microprocessor-running-at-3Ghz-and-a-ups-constantly-monitoring-ameter-with-built-in-temperature-alitiude-ultra-protecto-circuit ? Go look at your car, chances are it has an electric fan with a relay and a fuse. Thats it.

The conditions of the fan are not out of the ordinary and I'm certain the fan can handle being run for a long period of time with no damage (they are warranteed for 3 years)

What I'm wondering is if the fan siezed up why didn't it blow a fuse... Why after two dead fans has the fuse not poped (I checked the fuse with another and that didn't blow either.

I'm not sure what will happen with a lower rated fuse... If it doesn't pop just as this current one isn't popping then I have no idea where the problem could be.... Connecting the battery terminals with a 30amp fuse in between (ie: a shorted fan) should pop a 50amp fuse with no problem... If I put a lower amp fuse in and it DOES pop... well, then I guess I must have a crappy connection somewhere (no ?)

Ideas ?

LOL.... :shock: But you still dont know why your fan dies..

"a shorted fan should pop a 50amp fuse" well, yes if it failed with a nice solid short.. I think it is an important clue, that the mfg said "over amperage" yet your fuse didnt pop. Well, not everything in the world fails short or open. It could, I suppose have failed with a couple ohms short.. enough to fry it but not enough to pop a presumably SLOW blow fuse.

..and added protection is assuming you may have something else wrong in the system that you have not ruled out... There is always the chance of more than ONE problem going on.. if your issue was a simple no-brainer, you'de have solved it by now eh?

Isnt it amazing how sometimes the simplest of things turn in to real head scratchers..

 

[iso9001]

I'm not going to split hairs about what term they used. This is company I deal with now and then and do not think they're 'conning' me.

If the fan were to stop... say because it was being jammed up by somthing (really really unlikely) would that also not blow a fuse ? Also: WHY AM I NOT BLOWING FUSES WITH A DEAD FAN !? (frustrating :evil: )

Part of the deal was that I can not open the motor w/o kissing my fan replacment goodbye. I have no idea what it looked like inside but was on the phone w/ the tech when he cracked it open. He said it was completely trashed. That the solder on the brushes had completely melted away.

This is a very modern car and I have measured no spikes higher then 40V when starting. This is not some old unreliable pos. If I were pulling too much current why isn't my fuse popping? I mean, how can the fan be getting to much but the fuse is within operating range. Its not like the fuse is a regulator, it doesn't care if there is 0 and 29amps on the line. I really really doubt the fan is getting stuck or blocked up, so what could cause it to "pull" too much current w/o any damage to the fuse or relay ?

The controller has a 2 second timed delay per operation. Where it can not turn the fan on or off more then once every 2 seconds. Even then I have a deadband in there to make sure the fan doesnt just keep turning on or off every cycle. At idle the fan will turn on, the radiator will cool then engine down and about a minute later the fan will shut off, then when it gets hot again, fan on. (This is how YOUR car works too.)

Normal voltage at idle is ~12V. Like I said this is a very new system and not really prone to the same quirks as an older car.

I'm using a relay since I already have one for the fan. NPNs are cheap. And I have found mosfets a little too 'sensitive" for my tastes. (I had this system on a mosfet that would trigger whenever it wanted to unless I touched the fet with my finger... the problem was it was not biased to ground... like I said, too sensitive. I just couldn't see that thing lasting forever). This fan has a reputation for being the best in the wold and I have not found another that could possibly fit this application. Besides I think the problem is with somthing else in the car.

I really appreciate all tje help! This is frustrating for me and I've tried everything short of ripping it all out and starting over (VERY VERY tough to do since all the wires are sealed up in the factory convelute)

The tech suggested that although he doesn't know the system that maybe I have a poor connection somewhere and its just enough stress on the fan to burn it up but not enough to blow my 30amp fuse ?

Does that stick ?

 

[iso9001]

Optikon: Your on the right track,

This is a slower then normal fuse I belive.

Do you think its possible that the fan even in its dead state is sucking up just enough current not to blow that fuse ?

What I dont understand is that when the fan is dead, if you connect it to the battery, this thing lights up like a sparkler... So why doesnt it blow the fuse once its already dead ?

Maybe I have a bad solder connector that is just roughly a few ohms poor of perfect that is heating up the fan ? (But that gets me back to the fuse again :?: )

 

[Optikon]

I'm using a relay since I already have one for the fan. NPNs are cheap. And I have found mosfets a little too 'sensitive" for my tastes. (I had this system on a mosfet that would trigger whenever it wanted to unless I touched the fet with my finger... the problem was it was not biased to ground... like I said, too sensitive. I just couldn't see that thing lasting forever). This fan has a reputation for being the best in the wold and I have not found another that could possibly fit this application. Besides I think the problem is with somthing else in the car.


The tech suggested that although he doesn't know the system that maybe I have a poor connection somewhere and its just enough stress on the fan to burn it up but not enough to blow my 30amp fuse ?

Does that stick ?

Don't let a bad experience with a mosfet put a sour taste in your mouth. A properly designed mosfet switch circuit will far far far far outlive your fan, relays and you very likely. Relays being mechanical in nature, are the most unreliable elctronics you have in there, second only to the fan itself.

Since the fusing seems to be in question (it is isnt it? 30 vs 50, why no blow etc..) I think this should be straightened out first. Can the tech tell you precisely what the fan needs to draw? It wouldnt be the first time failures like this happened because the fuses were not properly sized but worked in "most" systems..

 

[iso9001]

He mentioned nominal pull is ~12amps.

The company I went through to get the fan brought in sends out a stupid relay harness that they make that has a 30amp fuse in it... So upon seeing that thing I said "Well, THEY supply a 30amp fuse, thats what I'LL use"... (dumb)

I made the whole system so that when I sell the car, any none electronics guy can just replace the relay if it brakes. (I doubt my NPN/PCB setup in about 3oz of potting compound will fail before then rest of the car)

 

[zevon8]

One thing that there is alot of misunderstanding about in regard to fuses, they are really meant to protect the wiring, not the device. The other thing is that they do not respond instantly to the rated current.

For example, a 30 Amp fuse will not open circuit instantly at 30 Amps, infact, it is designed to carry 30 Amps. From the Littlefuse catalog, ( one of the worlds largest fuse producers ) a 30 Amp, ATO style automotive fuse has a MINIMUM opening time of 100 hours with 110% of rated current flowing through it. This means it will take a minimum of 100 hours to open circuit with 33 Amps flowing through it. For the same 30 Amp fuse to open circuit in less than 1 second ( maximum 600 seconds ), it requires 40 Amps.

You will definitely have done damage in this amount of time if the fan has a nominal operating current of about 12 Amps.

Taking into account the fans inrush current, even at say 20 Amps, for a duration of maybe 0.5 seconds, you need something more in the order of a 15 Amp fuse.

I think that this fan suffered from insufficient cooling, and baked itself. Fan motors are notorious for having extreme temperature rise, since they generally in their own airstream, and can/should be self cooling. It is not uncommon to see a rating of 60*C over ambient on a fan motor. Try touching something that is 60*C. And then remember that this is 60*C over ambient, so add the temperature of the radiator air to that figure.
At these temps, its really easy to melt solder, burn windings, dry-up and seize bearings, etc.

I think the manufacturer is giving you the run-around. If it was installed as marketed, used under normal operating conditions, and failed that quickly, something is wrong with it. Bottom line.

 

[martinH]

Does the motor have built in suppresors, if not the you should fit
a automotive supressor as near to the + of the motor to stop the brushes
arcing and overheating(sure way to kill a motor).
When you connected your "dead" motor across the battery, you say it lit up,
this was due to the brushes arcing on the commutator which possibly would not blow your 30 amp fuse , but a short circuit armature would deffinitly blow the fuse(or send out smoke signals).


Martin

 

[zachtheterrible]

i dunno if someone already mentioned this, but if the fan needs time to shut off and cool down once in a while, maybe the fan is somehow being always on and therefore ruining it.

 

[jrz126]

Do you still have this 30A fuse? maybe a "smoke" test is needed, go and short that guy out and see if it'll pop.

 

[Exo]

Maybe I have a bad solder connector that is just roughly a few ohms poor of perfect that is heating up the fan ? (But that gets me back to the fuse again :?: )

A bad connection/few extra ohms will actually reduce current, not increase it.

Part of the deal was that I can not open the motor w/o kissing my fan replacment goodbye. I have no idea what it looked like inside but was on the phone w/ the tech when he cracked it open. He said it was completely trashed. That the solder on the brushes had completely melted away.

well, maybe that was the problem then, there shouldn't be any solder on the brushes! :lol:

 

[williB]

Part of the deal was that I can not open the motor w/o kissing my fan replacment goodbye. I have no idea what it looked like inside but was on the phone w/ the tech when he cracked it open. He said it was completely trashed. That the solder on the brushes had completely melted away.

well, maybe that was the problem then, there shouldn't be any solder on the brushes! :lol:

thats true..are ya sure that this tech KNOWS what he is talking about..
i had a fan for the heater core go on me once ..heated the brushes up so much that it melted the PLASTIC that held them in place.. this was caused by the bearing which was putting a drag on the motor ..

 

[Optikon]

One thing that there is alot of misunderstanding about in regard to fuses, they are really meant to protect the wiring, not the device. The other thing is that they do not respond instantly to the rated current.

For example, a 30 Amp fuse will not open circuit instantly at 30 Amps, infact, it is designed to carry 30 Amps. From the Littlefuse catalog, ( one of the worlds largest fuse producers ) a 30 Amp, ATO style automotive fuse has a MINIMUM opening time of 100 hours with 110% of rated current flowing through it. This means it will take a minimum of 100 hours to open circuit with 33 Amps flowing through it. For the same 30 Amp fuse to open circuit in less than 1 second ( maximum 600 seconds ), it requires 40 Amps.

You will definitely have done damage in this amount of time if the fan has a nominal operating current of about 12 Amps.

Taking into account the fans inrush current, even at say 20 Amps, for a duration of maybe 0.5 seconds, you need something more in the order of a 15 Amp fuse.

I think that this fan suffered from insufficient cooling, and baked itself. Fan motors are notorious for having extreme temperature rise, since they generally in their own airstream, and can/should be self cooling. It is not uncommon to see a rating of 60*C over ambient on a fan motor. Try touching something that is 60*C. And then remember that this is 60*C over ambient, so add the temperature of the radiator air to that figure.
At these temps, its really easy to melt solder, burn windings, dry-up and seize bearings, etc.

I think the manufacturer is giving you the run-around. If it was installed as marketed, used under normal operating conditions, and failed that quickly, something is wrong with it. Bottom line.

I agree. I also think the fuse is improperly sized allowing for a situation that can destroy the device but not blow the fuse. Now, the seperate issue is why the fan dies in the first place.

Either it is being overstressed by the environment (i.e. operating out of specs) this could be nasty voltages, insufficient airflow etc etc..

Or, there was something wrong with it to begin with as you mentioned.

ISO9001 seems fairly confident that it is not overstressed by the environment so a manufacturing defect of sorts is not out of the question yet.. at least until more data is discovered.

ISO, slow blow types are what you want (for inrush current reasons) but the rated carry capacity, you want to have not much above what the fan actually needs. Also, if it can carry full rated current for many hours, thats more than enough! If the fan is trying to remain running for hours then something else is wrong because its not doing a good job cooling.

 

[plot]

Re: Starts per second ?

The fan is controlled by a pic. It reads in the coolant temp sensor and triggers a NPN transistor to connect the relay coil to ground. This is a proven working system. And since its on the control side of the relay, and the relay is only triggering when its supposed to.

Is it possible that the controller is starting and stopping the fan a LOT - causing it to draw the start-up current, stop again, draw the start-up current, with no rest (cool-down) time ?

I don't like the "too much current" idea - too much current must have been caused by :-
- too much voltage (Phasor's idea)
- too frequent starting causing overheating of the motor coils
- faulty manufacture (as you said - unlikely - but not totally impossibe, are they from the same batch?)
- stalling (fairly obvious - dead dog wedged through radiator ?!)

Could the fan be happier without the PIC controller (just wired to ignition switch - a bit crappy but it could (dis)prove an idea)?

maybe stick in a power mosfet controlled by the pic, and somehow code the pic to put out a few different levels of current... in this manner the fan would never be off, just slowed down and sped up.

maybe hook the base of the fet to two or three pins of the PIC with a resistor on each pin, output 111 to get full speed, 100 to get slowed down mode.

 

[BlackBart]

Bad Fan

I might as well throw in my 2 cents worth, #1 check that the fan is
blowing toward the engine when energized , #2 check that the fan does
not come on until the engine has heated a little above normal, not as soon
as the engine is turned on. # If the two above are correct check that the
fan turns off when normal operating temp is reached.

I suspect that one or more of the above conditions are not being met.

Dave

 

[williB]

Re: Starts per second ?

The fan is controlled by a pic. It reads in the coolant temp sensor and triggers a NPN transistor to connect the relay coil to ground. This is a proven working system. And since its on the control side of the relay, and the relay is only triggering when its supposed to.

Is it possible that the controller is starting and stopping the fan a LOT - causing it to draw the start-up current, stop again, draw the start-up current, with no rest (cool-down) time ?

I don't like the "too much current" idea - too much current must have been caused by :-
- too much voltage (Phasor's idea)
- too frequent starting causing overheating of the motor coils
- faulty manufacture (as you said - unlikely - but not totally impossibe, are they from the same batch?)
- stalling (fairly obvious - dead dog wedged through radiator ?!)

Could the fan be happier without the PIC controller (just wired to ignition switch - a bit crappy but it could (dis)prove an idea)?

maybe stick in a power mosfet controlled by the pic, and somehow code the pic to put out a few different levels of current... in this manner the fan would never be off, just slowed down and sped up.

maybe hook the base of the fet to two or three pins of the PIC with a resistor on each pin, output 111 to get full speed, 100 to get slowed down mode.

i see what you are saying , but with a FET i would use a Digital to Analog Converter, with a NPN power transistor your idea would work, he could get three different Values of resistors ... this is all assuming that the NPN will turn on with 25 mA , or less, applied to the base.. i dont see why not..

 

[iso9001]

oh hell.

I still have not found out what is wrong with the fans, but I did speak to another tech who said "yea, thats kind of a bullsh¡t answer" so I'm trying a newer slightly larger fan. Same diameter and everything just a larger motor... After speaking with a lot of different people I'm starting to think that maybe I just got 2 bad fans. They DID come out of the same batch I believe

I'm starting to think that nothing I have is screwed up. YES for the last time the fan spins the right way. YES my pic turns it on and off at the right temps w/ a 10degree dead band.

Seriously, using a mosfet AND a D/A? This is a 15-20amp fan. You do NOT want to try and use resistors, they'll be huge and hot. If I wanted to slow it down a little, PWM is the way to go. I recently found out thats how the OEM does it.

Mosfets may be better then my NPN (which I'm pretty sure will last forever). But they are too damn sensitive for my liking.

No one at this company ever heard of two bad fans, hell most people never ever ever heard of one. But since I cant figure out whats wrong with it, I'll just toss a new (free) fan in and watch.

 

[williB]

oh hell.

I still have not found out what is wrong with the fans, but I did speak to another tech who said "yea, thats kind of a bullsh¡t answer" so I'm trying a newer slightly larger fan. Same diameter and everything just a larger motor... After speaking with a lot of different people I'm starting to think that maybe I just got 2 bad fans. They DID come out of the same batch I believe

I'm starting to think that nothing I have is screwed up. YES for the last time the fan spins the right way. YES my pic turns it on and off at the right temps w/ a 10degree dead band.

Seriously, using a mosfet AND a D/A? This is a 15-20amp fan. You do NOT want to try and use resistors, they'll be huge and hot. If I wanted to slow it down a little, PWM is the way to go. I recently found out thats how the OEM does it.

Mosfets may be better then my NPN (which I'm pretty sure will last forever). But they are too damn sensitive for my liking.

No one at this company ever heard of two bad fans, hell most people never ever ever heard of one. But since I cant figure out whats wrong with it, I'll just toss a new (free) fan in and watch.

good , i was hoping that you didnt have to buy a new one..
BTW is there any way to test the fan before installation..??

 

[ante]

A friend of mine had a similar problem with his “toy” Camaro many years ago. The fuse blew but only when he was driving fast, never when he was waiting for the red lights and the fan was starting and stopping all the time. He asked me if I could check his alternator and I did, nothing wrong here. I checked the rotation and the wiring and relay, all in good condition. Then I put in an A-meter so that we could measure the current while he was driving. When driving slowly down the street and the fan kicked in the meter showed 25A very shortly and then stabilised at about 10A until it stopped. But on the country road doing 100 the meter went out of scale (50A) and the fuse blew. After some tests we pulled of the hood with the scoop (fibreglass) and tried again …no problem. The scoop was the culprit catching lots of air at high speed making the fan go backwards. I don’t know if you have any scoop on your hood but if you do check if the fan is going the right way when driving. If the fan has a PM motor it’s easy just connect a voltmeter and you can se the polarity of the generated voltage and you know which way it turns.

Ante :roll:

 

[iso9001]

Resolution !

I got my new fans in today and so far so good. No problems, tried to abuse it all day and its working fine.

Looks like maybe I just got a bum fans from a company that tells me they have never before seen a bad fan at all. Go figure I get the only two ever made wrong. :?

Thanks for your help everyone,

 

[Phideaux]

Resolution !

I got my new fans in today and so far so good. No problems, tried to abuse it all day and its working fine.

Looks like maybe I just got a bum fans from a company that tells me they have never before seen a bad fan at all. Go figure I get the only two ever made wrong. :?

Thanks for your help everyone,

Just curious; are the fans still working properly?