Electric fan relays

7991LXnSHO · Aug 23, 2020

I have been reading about a Bosch 75A related for running the OEM style of fans. I was at Menards and saw what might be a cheaper, effective alternative. Electric start mowers have a smaller version of the Ford starter relay (aka solenoid). I am sure the amp rating of a starter motor for a 20+ hp engine is at least 75 amps. I am not sure about the constant duty cycle rating on it. Has anyone used these for another purpose than starting yard products or motorized toys?
Also, is this link for the right Bosch relay?

Bosch/TYCO Relay SPST 12-Volt 75-Amp with Mounting Tabs (V23232-D0001-X001) from Solid Signal

Bosch/TYCO Relay SPST 12-Volt 75-Amp with Mounting Tabs (V23232-D0001-X001) TYCO single pole, single throw relay. 12 volt, 75 A resistance load. For use with light bars. Case includes two molded mounting tabs. Typical applications: engine control, glow plug, heated front - and rear - screen...

www.solidsignal.com

Foxslider · Aug 23, 2020

I just wired up my contour fans with 2 30a relays. 1 relay for each fan. Its a simple key on fan on operation. (Coolant sensor red wire) The relays are $7 a pop on ebay. X2= $15. Add $15 in 10ga wiring from local oreillys, $10 for terminal assortment kit, $5 shrink wrap assortment from harbor/elec tape. $6 solder gun. $6 solder. Fans $50 at JY. Make brackets, $2 a pc out of the thin mending plate, easy to work with. X4 so $8. Bolts/nuts/washers/lock washers, Zipties, Thats about it. $120. Vs $3-400.

My car idled forever and never got over 210 ish. (@ 92+ degree ambient) Felt peppier also with the 5hp+ parasitic loss that got dropped.

I know this has nothing to do with the question, but i want to brag about my achievement. Lol.

Mustang5L5 · Aug 24, 2020

I believe I have the one in the photo (Bosch/Tyco), but this appears to be the same relay for a little cheaper price. I can go check later.

Amazon product ASIN B0117FAGVOView: https://www.amazon.com/Bosch-332-002-168-0332002168/dp/B0117FAGVO/ref=asc_df_B0117FAGVO/?tag=bingshoppinga-20&linkCode=df0&hvadid=&hvpos=&hvnetw=o&hvrand=&hvpone=&hvptwo=&hvqmt=e&hvdev=c&hvdvcmdl=&hvlocint=&hvlocphy=&hvtargid=pla-4584276296427787&psc=1

I bought mine 20 years ago and it still works flawlessly today. I only run a single fan. I wired it so that my aftermarket fan controller (which only has a 30A relay) just turned the 75A relay on rather than directly powering the fan. I've measured the draw of my 94-95 Sn95 efan and it was only 35AMPs continuous.

When I go Megasquirt, I plan on using a volvo PWM fan controller with the MS3x to control the fan.

There are many many ways to skin a cat here in terms of fan control.

96pushrod · Aug 24, 2020

Leash sells a nice relay module which can be used for e fans. Comes with a 70a relay, and has provisions for a fuse so you don’t need to run one inline.

1HO Single 70amp relay module

Single 70 amp relay module. Has heavy duty 70 amp industrial relay. Uses heavy duty J-case/FMX fuses (NOT INCLUDED). #10 battery input and relay output studs. Led indictor on output.

leashelectronics.com

I ran one of the big 100 amp relay when I required the sn95 fan I used. They’re the ones with the large pins on them, but they’re comparable to a standard size relay. Got it off amazon for around $12 for 2.

Blown88GT · Aug 24, 2020

The Bosch relay is the one you want for starting large motor loads. Get the version with the diode across the relay coil.
P/N 0-332-002-156
Amazon product ASIN B004AFWZ1IView: https://www.amazon.com/Bosch-Automotive-0332002156-Relay/dp/B004AFWZ1I

Blown88GT · Aug 24, 2020

Mustang5L5 said:
I believe I have the one in the photo (Bosch/Tyco), but this appears to be the same relay for a little cheaper price. I can go check later.

Amazon product ASIN B0117FAGVOView: https://www.amazon.com/Bosch-332-002-168-0332002168/dp/B0117FAGVO/ref=asc_df_B0117FAGVO/?tag=bingshoppinga-20&linkCode=df0&hvadid=&hvpos=&hvnetw=o&hvrand=&hvpone=&hvptwo=&hvqmt=e&hvdev=c&hvdvcmdl=&hvlocint=&hvlocphy=&hvtargid=pla-4584276296427787&psc=1

I bought mine 20 years ago and it still works flawlessly today. I only run a single fan. I wired it so that my aftermarket fan controller (which only has a 30A relay) just turned the 75A relay on rather than directly powering the fan. I've measured the draw of my 94-95 Sn95 efan and it was only 35AMPs continuous.

When I go Megasquirt, I plan on using a volvo PWM fan controller with the MS3x to control the fan.

There are many many ways to skin a cat here in terms of fan control.

That's almost the same one as the -156. Don't know what the difference is.

Mustang5L5 · Aug 24, 2020

Looks like I was a little off. Here’s the one I’ve used in my car

Amazon product ASIN B004AFWZ1IView: https://www.amazon.com/Bosch-Automotive-0332002156-Relay/dp/B004AFWZ1I

7991LXnSHO · Aug 25, 2020

So is the diode is to prevent the motor working like a generator going down the highway or after the car is shut off?
The small engine solenoid is much cheaper, but if this is so reliable, the cost is not an issue.

Mustang5L5 said:
Looks like I was a little off. Here’s the one I’ve used in my car

Amazon product ASIN B004AFWZ1IView: https://www.amazon.com/Bosch-Automotive-0332002156-Relay/dp/B004AFWZ1I

jrichker · Aug 25, 2020

7991LXnSHO said:
So is the diode is to prevent the motor working like a generator going down the highway or after the car is shut off?
The small engine solenoid is much cheaper, but if this is so reliable, the cost is not an issue.

Wrong answer...

Using a diode as a dampener in automotive circuits:

Theory of operation:
The diode acts as a surge absorber or one way gate. Anytime you turn the power off an inductive load (coil, motor, solenoid, etc) the collapse of the magnetic field creates a voltage spike of opposite polarity to the voltage applied. The positive wire sees a negative spike and the negative wire sees a positive spike. The diode is wired backwards so that it does not conduct during normal forward operation. When the magnetic field collapses, the diode sees the reverse polarity spike and clamps it. This prevents the spike from possibly damaging the rest of the electronics in the car.
When used to clamp spikes in automotive circuits, connect the lead that comes from the end of the diode that has the band on it to the positive side of the circuit. Connect it the other way and you will make smoke.

Diode markings

A properly functioning diode will measure very high resistance or open circuit in one direction. Reverse the meter leads and it will measure a lower resistance.

Mustang5L5 · Aug 25, 2020

7991LXnSHO said:
So is the diode is to prevent the motor working like a generator going down the highway or after the car is shut off?
The small engine solenoid is much cheaper, but if this is so reliable, the cost is not an issue.

It’s been in my car damn near 20 years. I realize the car sat for 10 of those, but the relay also sat and aged as well and I’ve never had a hiccup with it. I’m running about 35a through it

7991LXnSHO · Aug 25, 2020

Why the sarcasm, J.? I know how a diode works. I asked what it did in this circuit and appreciate the rest of the answer.

jrichker said:
Wrong answer...

Using a diode as a dampener in automotive circuits:

Theory of operation:
The diode acts as a surge absorber or one way gate. Anytime you turn the power off an inductive load (coil, motor, solenoid, etc) the collapse of the magnetic field creates a voltage spike of opposite polarity to the voltage applied. The positive wire sees a negative spike and the negative wire sees a positive spike. The diode is wired backwards so that it does not conduct during normal forward operation. When the magnetic field collapses, the diode sees the reverse polarity spike and clamps it. This prevents the spike from possibly damaging the rest of the electronics in the car.
When used to clamp spikes in automotive circuits, connect the lead that comes from the end of the diode that has the band on it to the positive side of the circuit. Connect it the other way and you will make smoke.

Diode markings

A properly functioning diode will measure very high resistance or open circuit in one direction. Reverse the meter leads and it will measure a lower resistance.

jrichker · Aug 26, 2020

7991LXnSHO said:
Why the sarcasm, J.? I know how a diode works. I asked what it did in this circuit and appreciate the rest of the answer.

No sarcasm or insult was intended.

Most of the people here don't understand electricity and I have limited ways of understanding the depth of electrical knowledge. Therefore I spell out the details to try to give them some understanding of how it works.

General karthief · Aug 26, 2020

jrichker said:
No sarcasm or insult was intended.

Most of the people here don't understand electricity and I have limited ways of understanding the depth of electrical knowledge. Therefore I spell out the details to try to give them some understanding of how it works.

you are very helpful to the 'electronically impaired' like myself. The only thing I'm sure is electricity is not like water and does not always run downhill.

7991LXnSHO · Aug 26, 2020

jrichker said:
No sarcasm or insult was intended.

I must have read “wrong answer” in the tone of my teenagers having a bad day.

The voltage spike from a collapsing field is what induces a higher, spark capable voltage spike in the secondary windings of an ignition coil.
The two diodes on the relay schematic diagram are both on the trigger side (terminal 86). It seems that a high current capacity diode on the load side (terminal 87) would be a more effective if the open points is not enough to clamp the voltage spike.

What I not understand, and may not be fully applicable here, are reports of electric fans causing run on in points and HEI carbureted cars. How a fan’s reverse voltage spike or generated power can overcome the open points and continue to power the ignition without being miswired Is an explanation I would like to hear. If the relay with the two diodes in the trigger side fixes this, I need to “relay” the info.

Dennis-87GT · Aug 29, 2020

I recently added contour fans with a DCC Control FK-45 PWM controller. The controller cost twice as much as the fans, but I am very happy with this setup. Fans start "soft" and ramp up to speed, and run much more quiet as they run only as fast as is needed to cool the car. In my 302 with a Vortech, that seems to be about half speed max so far.

s50 s70

Blown88GT · Aug 29, 2020

I guess math was not your best subject?
$4 more does not make it twice as much.
FK-45 is $149.95
Dual Contour Fans are $145.95

Mustang Contour Electric Fan Assembly (79-93) - LMR

Convert your Fox Body cooling fan to electric with this 1979-1993 Mustang Contour electric fan assembly!

lmr.com

KRUISR · Aug 29, 2020

Blown88GT said:
guess math was not your best subject?
$4 more does not make it twice as much.
FK-45 is $149.95
Dual Contour Fans are $145.95

Actually the controller will be more than double if you pick up the fans from the wreckers, usually $30-40 there.

Electric fan relays

7991LXnSHO

wanna catch the space herp

Bosch/TYCO Relay SPST 12-Volt 75-Amp with Mounting Tabs (V23232-D0001-X001) from Solid Signal

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Foxslider

im not that much of a idiot

Mustang5L5

That is…until I whipped out my Bissell

96pushrod

I think they're a little easier to get off

1HO Single 70amp relay module

Blown88GT

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Mustang5L5

That is…until I whipped out my Bissell

7991LXnSHO

wanna catch the space herp

jrichker

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Mustang5L5

That is…until I whipped out my Bissell

7991LXnSHO

wanna catch the space herp

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wonder how much it would cost to ship you a pair

7991LXnSHO

wanna catch the space herp

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Mustang Contour Electric Fan Assembly (79-93) - LMR

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