Excessive Amperage Broke My Fan !? - Page 3 - Electronic Circuits Projects Diagrams Free

williB · 28th October 2004, 09:30 PM

Quote:

Originally Posted by iso9001

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 · 28th October 2004, 10:24 PM

Quote:

Originally Posted by 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.

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 · 28th October 2004, 11:33 PM

Quote:

Originally Posted by mechie

Quote:

Originally Posted by iso9001

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 · 7th November 2004, 10:32 PM

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 · 8th November 2004, 02:41 AM

Quote:

Originally Posted by plot

Quote:

Originally Posted by mechie

Quote:

Originally Posted by iso9001

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 · 15th November 2004, 08:27 PM

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 · 16th November 2004, 01:21 AM

Quote:

Originally Posted by 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.

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 · 17th November 2004, 08:45 AM

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 · 19th November 2004, 05:42 PM

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 · 10th August 2005, 06:11 AM

Quote:

Originally Posted by 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,

Just curious; are the fans still working properly?

drrogla · 10th August 2005, 07:16 AM

You could posibly put a large capacitor paralel to the fan to filter the spikes I guess. Would this help guys?

firebird67hotrod · 29th October 2009, 03:15 AM

Have you tried connecting the fans positive straight to the battery with an inline fuse, and the negatve to a switched relay. I have connected mine this way with no problems.

Dean Huster · 30th October 2009, 02:49 AM

Quote:

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.

Talk about a Rube Goldberg overkill !! Next think you know, it'll be a PC running Vista to control the thing. Anybody ever hear of a thermostat?

ke5frf · 30th October 2009, 04:04 AM

Quote:

Originally Posted by Nigel Goodwin

Is it a North American term then?, it's certainly not a European one, and not something I've ever seen in any American texts.

I don't know about North American vs European, but an over-current condition caused by a motor with bad bearings or an over-burdened or seized rotor is often called "LOCKED ROTOR AMPS"...and we often use the term "amperage" to signify current draw with electrical systems, especially AC/home wiring etc, motors, contactors, and refrigeration.

Not so much with (ordinary) *electronic* circuits because they rarely draw more than an amp or two anyway.

As far as the fan motor is concerned, is this occuring in the wintertime or a cold environment?

The time frame wasn't specified.

I have a general motors vehicle that has a "secondary intake" fan associated with the manifold. I get a check engine every few months because I have a bad checkvalve that allows condensation to backflow and either rust the bearings or freeze and sieze the motor in cooler months.

Instead of replacing it for the third time I have decided it is an unnecessary nuisance warning with minimal effect on my fuel efficiency and emissions. I'm a year away from replacing the vehicle anyway.

At any rate, just a thought if Ice may be your culprit, or at least might have been for one of them.

ke5frf · 30th October 2009, 04:08 AM

Also remember, my question may be dumb for those of us in the Northern hemi who are just coming into the winter months, but I know Southern hemi posters abound here as well.

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7th November 2004, 10:32 PM	#34
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

15th November 2004, 08:27 PM	#36
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.

17th November 2004, 08:45 AM	#38
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:

19th November 2004, 05:42 PM	#39
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,

10th August 2005, 07:16 AM	#41
drrogla	You could posibly put a large capacitor paralel to the fan to filter the spikes I guess. Would this help guys?

29th October 2009, 03:15 AM	#42
firebird67hotrod	excessive amperage Have you tried connecting the fans positive straight to the battery with an inline fuse, and the negatve to a switched relay. I have connected mine this way with no problems.

30th October 2009, 04:08 AM	#45
ke5frf	Also remember, my question may be dumb for those of us in the Northern hemi who are just coming into the winter months, but I know Southern hemi posters abound here as well.