# [EVDL] Fan speed control



## EVDL List (Jul 27, 2007)

Hi all,

I'm looking for a way to control the speeds of up to four fans based 
on temperature readings.

I live in southern New Mexico (USA) and the temperatures in summer 
routinely exceed 100 degrees F (38 degrees C). I want my EV 
components to last a while so I'm considering ways to keep them cool 
and dry. The components live in the engine compartment of an 
aircooled VW. I've blocked off the bottom of the engine compartment 
to guard against road debris and spray, but the top is vented. The 
vent has a drip tray, but I don't trust it to catch all the water from 
our infrequent cloudbursts and rather more frequent car washes.

I started out thinking that something for the custom PC hobbyists 
would do the trick, but I can't seem to find anything that 
*automatically* controls the fan speeds. The ones I'm finding all use 
knobs.

I could just leave them all on High, but that would probably make the 
EV noisier than the average ICE. I would like it to run as quietly as 
possible, hence temperature control.

Is this a good assumption? Or would I be OK with a "set and forget" 
system based on knobs or a dashboard High/Low/Off switch?

The fans I want to control are:

1) cooling fan on the Zilla radiator (two 12v 120mm muffin fans)
2) cooling fan for water-resistant box around the Zilla, Hairball, DC/ 
DC converter (also liquid cooled by the Zilla cooling loop), and four 
SW200 contactors.
3) big Dayton 12v blower for cooling the motor (8in ADC)
4) cooling fan for box around large inverter for running air 
conditioning compressor (near future project)
5) future expansion options would be appreciated

... more or less in that order. Actually, advice on the order would 
also be appreciated - I've prioritized the implementation of the fans 
in this order. Does that look OK?

I'd hate to have to build an Arduino-based system, then program and 
debug it. (Well, actually it sounds like a lot of fun, but I'd rather 
just buy something already built and debugged.)

Any other advice would be appreciated. Even if your US English 
grammar and spelling is less than perfect. (Oh no, that was a 
sentence fragment. Good thing I waited until the end of the message!)

TIA,

Doug

--
Doug Weathers
Las Cruces, NM, USA
<http://www.gdunge.com/>

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## EVDL List (Jul 27, 2007)

I think I'm missing something. Why not use 4 thermostats?



> Doug Weathers <[email protected]> wrote:
> > Hi all,
> >
> > I'm looking for a way to control the speeds of up to four fans based
> ...


----------



## EVDL List (Jul 27, 2007)

Doug
You can find computer based fans that have built in thermistors. I have
one in my car computer. For example
http://www.newegg.com/Product/Product.aspx?Item=N82E16811999145

There are two other options. One build it yourself. Take a thermistor
and mount it to the device you want to cool with the fan and then rig up a
circuit with a transistor (or something, never built one, but know it can
be done) to drive the fan faster or slower based on temp.

They also sell
http://www.newegg.com/Product/Product.aspx?Item=N82E16811999174
which I am not sure if it would accomplish the goal
http://www.newegg.com/Product/ProductList.aspx?Submit=ENE&DEPA=0&Description=fan+controller


The one thing I would caution you of though is that you may want to alter
the circuit some as the "full speed" temperature of those fans tends to be
higher than I would like it. I am sure with a little work you could
adjust it but just warning you that full speed may not hit until after you
want it so check the specs. Or you might find it perfect.

Good luck
Jeff

> Hi all,
>
> I'm looking for a way to control the speeds of up to four fans based
> on temperature readings.
>
> I live in southern New Mexico (USA) and the temperatures in summer
> routinely exceed 100 degrees F (38 degrees C). I want my EV
> components to last a while so I'm considering ways to keep them cool
> and dry. The components live in the engine compartment of an
> aircooled VW. I've blocked off the bottom of the engine compartment
> to guard against road debris and spray, but the top is vented. The
> vent has a drip tray, but I don't trust it to catch all the water from
> our infrequent cloudbursts and rather more frequent car washes.
>
> I started out thinking that something for the custom PC hobbyists
> would do the trick, but I can't seem to find anything that
> *automatically* controls the fan speeds. The ones I'm finding all use
> knobs.
>
> I could just leave them all on High, but that would probably make the
> EV noisier than the average ICE. I would like it to run as quietly as
> possible, hence temperature control.
>
> Is this a good assumption? Or would I be OK with a "set and forget"
> system based on knobs or a dashboard High/Low/Off switch?
>
> The fans I want to control are:
>
> 1) cooling fan on the Zilla radiator (two 12v 120mm muffin fans)
> 2) cooling fan for water-resistant box around the Zilla, Hairball, DC/
> DC converter (also liquid cooled by the Zilla cooling loop), and four
> SW200 contactors.
> 3) big Dayton 12v blower for cooling the motor (8in ADC)
> 4) cooling fan for box around large inverter for running air
> conditioning compressor (near future project)
> 5) future expansion options would be appreciated
>
> ... more or less in that order. Actually, advice on the order would
> also be appreciated - I've prioritized the implementation of the fans
> in this order. Does that look OK?
>
> I'd hate to have to build an Arduino-based system, then program and
> debug it. (Well, actually it sounds like a lot of fun, but I'd rather
> just buy something already built and debugged.)
>
> Any other advice would be appreciated. Even if your US English
> grammar and spelling is less than perfect. (Oh no, that was a
> sentence fragment. Good thing I waited until the end of the message!)
>
> TIA,
>
> Doug
>
> --
> Doug Weathers
> Las Cruces, NM, USA
> <http://www.gdunge.com/>
>
> _______________________________________________
> General EVDL support: http://evdl.org/help/
> Usage guidelines: http://evdl.org/help/index.html#conv
> Archives: http://evdl.org/archive/
> Subscription options: http://lists.sjsu.edu/mailman/listinfo/ev
>
>

_______________________________________________
General EVDL support: http://evdl.org/help/
Usage guidelines: http://evdl.org/help/index.html#conv
Archives: http://evdl.org/archive/
Subscription options: http://lists.sjsu.edu/mailman/listinfo/ev


----------



## EVDL List (Jul 27, 2007)

> storm connors wrote:
> 
> > I think I'm missing something. Why not use 4 thermostats?
> 
> ...


----------



## EVDL List (Jul 27, 2007)

A thermostat would be the easiest and simplest method. You want an
industrial type with a relay output. Look at www.omega.com to see
what's available, but buy from a surplus website to save money.

However, this is just on-off control, not speed control. Speed control
would be nicer because at moderate load, speed control will run
continuously at medium speed, while a simple thermostat will cycle
between off and full speed.

I don't know of thermostats that will control a fan to multiple
speeds, unless the fan accepts a 0-10V or 4-20mA input. What type of
fan are you using, anyways?

-Morgan LaMoore



> Doug Weathers <[email protected]> wrote:
> >
> > On Aug 11, 2008, at 11:42 AM, storm connors wrote:
> >
> ...


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## EVDL List (Jul 27, 2007)

Thanks for the reply!



> [email protected] wrote:
> 
> > Doug
> > You can find computer based fans that have built in thermistors. I
> ...


----------



## EVDL List (Jul 27, 2007)

Thanks for the reply.



> Morgan LaMoore wrote:
> 
> > A thermostat would be the easiest and simplest method. You want an
> > industrial type with a relay output. Look at www.omega.com to see
> ...


----------



## EVDL List (Jul 27, 2007)

> Doug Weathers <[email protected]> wrote:
> 
> >
> > I like Jeff's suggestion of a fan with a built-in thermistor that
> ...


----------



## EVDL List (Jul 27, 2007)

As I mentioned you can build a controller if you really want to but the
first plans I found were a bit more complex
http://www.edn.com/contents/images/30404di.pdf
The above link involves using and IC and quite a few other components.

So I tried to find something simpler
http://www.edn.com/archives/1997/092597/20di_04.htm
http://www.maxim-ic.com/appnotes.cfm/appnote_number/1125
http://www.uoguelph.ca/~antoon/circ/auto-fan.html
http://www.edn.com/article/CA200387.html

Then I found this guy. I don't know if he is reputable but if it works out
he is selling what you need.
http://www.pwmpower.com/temlpwm.html
He has Thermistor controlled PWM's for as many amps as you can dream of (for
a fan). At least he lists his phone number. Anyway if it works 50 bucks is
his smallest unit which is rated up to 3 amps. He has higher rated units in
there for those big blowers. No idea about this guy never seen his site
until tonight.




Interesting reading about closed loop control cooling systems
http://electronicdesign.com/Articles/ArticleID/7597/7597.html



I found also
http://para.maxim-ic.com/results.mvp?fam=fan_cntrl
which is a whole list of units for controlling fans. I am no EE but MAX6684
seems like it might be a good choice and is available at Digikey.com but
setting them up doesn't look totally trivial.
http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail?name=MAX6684ESA%
2B-ND
for $3.52 at quantity 1.
http://datasheets.maxim-ic.com/en/ds/MAX6684.pdf





-----Original Message-----
From: Doug Weathers [mailto:[email protected]]
Sent: Monday, August 11, 2008 4:18 PM
To: Electric Vehicle Discussion List
Subject: Re: [EVDL] Fan speed control


Thanks for the reply!



> [email protected] wrote:
> 
> > Doug
> > You can find computer based fans that have built in thermistors. I
> ...


----------



## EVDL List (Jul 27, 2007)

As I mentioned you can build a controller if you really want to but the
first plans I found were a bit more complex
http://www.edn.com/contents/images/30404di.pdf
The above link involves using and IC and quite a few other components.

So I tried to find something simpler
http://www.edn.com/archives/1997/092597/20di_04.htm
http://www.maxim-ic.com/appnotes.cfm/appnote_number/1125
http://www.uoguelph.ca/~antoon/circ/auto-fan.html
http://www.edn.com/article/CA200387.html

Then I found this guy. I don't know if he is reputable but if it works out
he is selling what you need.
http://www.pwmpower.com/temlpwm.html
He has Thermistor controlled PWM's for as many amps as you can dream of (for
a fan). At least he lists his phone number. Anyway if it works 50 bucks is
his smallest unit which is rated up to 3 amps. He has higher rated units in
there for those big blowers. No idea about this guy never seen his site
until tonight.




Interesting reading about closed loop control cooling systems
http://electronicdesign.com/Articles/ArticleID/7597/7597.html



I found also
http://para.maxim-ic.com/results.mvp?fam=fan_cntrl
which is a whole list of units for controlling fans. I am no EE but MAX6684
seems like it might be a good choice and is available at Digikey.com but
setting them up doesn't look totally trivial.
http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail?name=MAX6684ESA%
2B-ND
for $3.52 at quantity 1.
http://datasheets.maxim-ic.com/en/ds/MAX6684.pdf





-----Original Message-----
From: Doug Weathers [mailto:[email protected]]
Sent: Monday, August 11, 2008 4:18 PM
To: Electric Vehicle Discussion List
Subject: Re: [EVDL] Fan speed control


Thanks for the reply!



> [email protected] wrote:
> 
> > Doug
> > You can find computer based fans that have built in thermistors. I
> ...


----------



## EVDL List (Jul 27, 2007)

> [email protected] wrote:
> 
> > There are two other options. One build it yourself. Take a
> > thermistor
> ...


----------



## EVDL List (Jul 27, 2007)

> Ben wrote:
> 
> > On Mon, Aug 11, 2008 at 10:04 PM, Doug Weathers <[email protected]>
> > wrote:
> ...


----------



## EVDL List (Jul 27, 2007)

Doug;

The PFC chargers have a temperature controlled fan in them. The circuit uses
four op amps (one LM324) and a MOSFET to run the blower motor. The circuit
uses a 10K thermistor for a sense element. The circuit has a turn on surge
to get the motor started followed by a low base speed that keeps the blower
moving in the absence of any heat. Once the temperature goes over a
setpoint, the blower increases speed linearly until it reaches full speed.
There are 12 resistors, 3 capacitors and 2 diodes that hook everything
together. Changing the resistors move the setpoints. Changing the capacitors
change the ramp rates. This could be adapted to suit your needs. If enough
people are interested, I could do circuit boards and instructions to market
a kit to do this. You could be the tester and evaluator for the early kits.

Joe Smalley
Rural Kitsap County WA
Former owner of 48 Volt Fiesta
NEDRA 48 volt street conversion record holder
[email protected]



----- Original Message ----- 
From: "Doug Weathers" <[email protected]>
To: "Electric Vehicle Discussion List" <[email protected]>
Sent: Tuesday, August 12, 2008 3:09 AM
Subject: Re: [EVDL] Fan speed control


>
>


> Ben wrote:
> >
> > > On Mon, Aug 11, 2008 at 10:04 PM, Doug Weathers <[email protected]>
> > > wrote:
> ...


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## EVDL List (Jul 27, 2007)

> Joe Smalley wrote:
> 
> > Doug;
> >
> ...


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## EVDL List (Jul 27, 2007)

Joe

I have vent fans for my battery boxes that I turn on whenever I charge. 12
volt squirrel cage fans, low current draw. I'd love it if there was a way
for my PFC-30 to control these. I always run them, so I'm not as interested
in the temperature adjustment.

Dave Cover



> Joe Smalley <[email protected]> wrote:
> 
> > Doug;
> >
> ...


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## EVDL List (Jul 27, 2007)

Doug;

The blower in my Fiesta was drawing 26 amps at 26 volts and used a very
similar circuit. The only difference in the Fiesta circuit was that it ran
off 48 VDC and had a timer to let the fan run after the car was turned off
if the motor was still hot.

The schematic adaptation would be easy, the mechanical (heat) and wire
sizing issues will need to be solved.

Joe Smalley
Rural Kitsap County WA
Former owner of 48 Volt Fiesta
NEDRA 48 volt street conversion record holder
[email protected]


----- Original Message ----- 
From: "Doug Weathers" <[email protected]>
To: "Electric Vehicle Discussion List" <[email protected]>; "Joe Smalley"
<[email protected]>
Sent: Tuesday, August 19, 2008 10:26 PM
Subject: Re: [EVDL] Fan speed control


>
>


> Joe Smalley wrote:
> >
> > > Doug;
> > >
> ...


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