Electrical E-fan... Pulls Sooo Much Amperage. Help?

stang&2Birds · Jul 30, 2012

rustyruststang5 said:
is this a dcc http://www.dccontrol.com/selector.htm ?
what one would be good for a 98 v6 contour fan?
im using a spal right now in one of my cars and like it, but it is alittle on the expensive side... but so is that dcc.

http://www.dccontrol.com/constant_temperature_controllers.htm

The FK-55 is rated for 55amps continuous.
http://www.dccontrol.com/fk55data.pdf
http://www.dccontrol.com/npwmdir5.jpg

The FK-85 is rated for 85amps continuous.
http://www.dccontrol.com/fk85data.pdf
http://www.dccontrol.com/npwmdir85.jpg

IMHO, for my engine and may car, I got the FK-85. IMHO, the cost of a DCC is minor compared to the cost of a fan, upgraded alternator, upgraded wiring, added high current fuses, upgraded radiator, etc, etc.

IMHO, first put money where it counts and where it's important.

BTW, the stock thermostatic clutch fan is fine for most cars. Of course, that's assuming the clutch isn't worn (gee, it's been only 20 years - duh ), and it's not replaced with some POS cheap *ss generic replacement ***** clutch.

stang&2Birds · Jul 30, 2012

Adams91LX said:
This weekend I installed my Mk8 fan.. I made a relay harness myself, installed the new timing cover, water pump, p/s pump, alternator, and a/c compressor (94-95 accessory swap)..

Dude, you owe me $$$$$! Send it by paypal - NOW!!
Your original question was very good. It did make me if an ~1F-20F super cap would help with a fan, and by how much. But, more important, after someone else asked about the CFMs of fans in some other thread (I think on the "other" site), it got me thinking of all of the "hearsay" and "I measured" stuff about fans. It brought back nasty memories about all of the incorrect info about springs (and there is still a lot!) that was "accepted as truth" because it was repeated in so many threads, and it may (or may not have) been based on what one person measured or said a zillion years ago.

The CFM of a fan in open space, may not be a good indicator of the CFM of a fan when it's connected to a radiator. Also, when people say "they measured the CFM", what EXACTLY does that mean? There are MANY variables! Without knowing the EXACT voltage and what EXACTLY was used to measure it, how it was measured, etc, etc, the CFM ratings that are repeated over and over could be off a lot!

So, my project for the Winter months:
Measure the "few electric fans" that I have. Measure then in open space. Record the input voltage. Document exactly what I did, what I measured, etc. Take videos - see for yourself exactly what I did, what I measured, how I measured it, my test setup, etc. Also, put the fans against a new radiator, yes I have spare. Keep the fan shrouds the same distance from the radiator(maybe 1/3"? I have to decide), take CFM measurements.

Measure the air velocity at a few points, see how consistent the airflow is from the outer top inner portion of the blade. Hey, check out the videos if you want that info. Too hard and too much work to try to make a general test and post results.

Also, take startup and steady state current measurements with a current probe and storage scope.

Maybe also take startup and steady state current measurements with a current probe and storage scope.

Throw results on the web.

I'm going to use an accurate hot wire anemometer. The twirly fan anemometer are fine for quick measurements. But, they suffer from bearing resistance, material accuracy, wear, etc.

So, you owe me the money that I just spent on an anemometer! Don't worry, I take paypal.

Yea, I need little "projects" like this every year to keep me entertained.
Yea, I'm an engineer - 110%, or should that be 150%, or 200%, or some other stupid percentage people quote? I love learning. I love seeing a question, looking to find answers (and determining the "basis and likely accuracy of the answers" ), and then seeing if I can somehow verify them myself.

Still, that does not mean that you don't owe me for the hot-wire anemometer that I just bought.

blackstangt · Jul 31, 2012

jrichker said:
On a good day, there are about 5 people who can do more that spell electricity here on Stangnet. Most of the people here are devoid of electrical knowledge, and shun electrical projects.

Since 2008, I have offered to send a free set of diagrams and a parts list for an prototype analog computer/PWM fan controller to all interested parties. In that time I have gotten maybe 5 requests. No one has ever emailed me back and said that they even tried to build it once they got the diagrams and parts list.

Stang&2Birds, here is your opportunity to be constructive or destructive.

This is a build it, troubleshoot it yourself item. I will not build or troubleshoot units, so it is not suitable for anyone who isn't really good with electronics.

To be fair to Stangers, I built an electric motorcycle and that system has more individual electrical components than my entire motorcycle. I did buy the motor controller instead of building one though.
Have you made one of these successfully?

One way of lowering draw would be to step down voltage, this should do the trick and be above stall voltage:
http://www.linear.com/product/LT3741
It's good for up to 20A, costs less than $6. The latemodelresto fan said 16A, so that should leave a good buffer.
Put that in-line with one circuit and it should reduce initial draw, connect a time delay relay between the first circuit and a second circuit:
http://www.wolstentech.com/products/timedelayrelay/timedelayrelay.php (less than $30)
and you now have a delayed voltage increase to normal voltage.

Manually, a couple switches and the voltage regulator would do the trick.
Automatically, add the time delay relay and you're good to go.
You may even be able to find cheaper parts than these or may need more complex parts for a different setup.

My cheap 16" Pep Boys fan and temperature sensor setup works just fine and I've had no problems while using a stock alternator and 700 RPM Idle. With a 3G alternator and a larger diameter wire, there should be no reason to deplete a battery because of a fan, even with underdrive pullies.

blackstangt · Jul 31, 2012

Jrichker and Stang& 2Birds, what do you guys think of that idea? I haven't actually built it, but do you think it's a valid alternative?

jrichker · Jul 31, 2012

FRom your posted link
"The LT3741 is a fixed frequency synchronous step-down DC/DC controller designed to accurately regulate the output current at up to 20A."

You need to be able to handle 30 amp minimum steady state current. Thant means you need external components or two of the little buggers to do the job. If you use two of them, then you have to figure out some way to be sure that the current draw is the equal for both controllers or one will handle most of the load and overheat.

I think PWM is the proper way to handle large current circuits.

blackstangt · Aug 1, 2012

I'm sure there's one that can handle more, is there any problem with it otherwise. The parts were from a quick search.

Noobz347 · Aug 1, 2012

stang&2Birds said:
Dude, you owe me $$$$$! Send it by paypal - NOW!!
Your original question was very good. It did make me if an ~1F-20F super cap would help with a fan, and by how much. But, more important, after someone else asked about the CFMs of fans in some other thread (I think on the "other" site), it got me thinking of all of the "hearsay" and "I measured" stuff about fans. It brought back nasty memories about all of the incorrect info about springs (and there is still a lot!) that was "accepted as truth" because it was repeated in so many threads, and it may (or may not have) been based on what one person measured or said a zillion years ago.

The CFM of a fan in open space, may not be a good indicator of the CFM of a fan when it's connected to a radiator. Also, when people say "they measured the CFM", what EXACTLY does that mean? There are MANY variables! Without knowing the EXACT voltage and what EXACTLY was used to measure it, how it was measured, etc, etc, the CFM ratings that are repeated over and over could be off a lot!

So, my project for the Winter months:
Measure the "few electric fans" that I have. Measure then in open space. Record the input voltage. Document exactly what I did, what I measured, etc. Take videos - see for yourself exactly what I did, what I measured, how I measured it, my test setup, etc. Also, put the fans against a new radiator, yes I have spare. Keep the fan shrouds the same distance from the radiator(maybe 1/3"? I have to decide), take CFM measurements.

Measure the air velocity at a few points, see how consistent the airflow is from the outer top inner portion of the blade. Hey, check out the videos if you want that info. Too hard and too much work to try to make a general test and post results.

Also, take startup and steady state current measurements with a current probe and storage scope.

Maybe also take startup and steady state current measurements with a current probe and storage scope.

Throw results on the web.

I'm going to use an accurate hot wire anemometer. The twirly fan anemometer are fine for quick measurements. But, they suffer from bearing resistance, material accuracy, wear, etc.

So, you owe me the money that I just spent on an anemometer! Don't worry, I take paypal.

Yea, I need little "projects" like this every year to keep me entertained.
Yea, I'm an engineer - 110%, or should that be 150%, or 200%, or some other stupid percentage people quote? I love learning. I love seeing a question, looking to find answers (and determining the "basis and likely accuracy of the answers" ), and then seeing if I can somehow verify them myself.

Still, that does not mean that you don't owe me for the hot-wire anemometer that I just bought.

I once thought I had caught a quark but as it turned out, it was only a pi-meson.

Electrical E-fan... Pulls Sooo Much Amperage. Help?

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Electrical E-fan... Pulls Sooo Much Amperage. Help?

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