Bypass ECU :: Radiator Fan Control Switch

spec said:

Hi pradoartz, I do not fully understand what you are planning on doing.

Let me explain: In order to design a circuit to replace the ECU fan control it is necessary to know what the replacement circuit will be driving, so that a correct design can be made.

Can I advise that you remove the ECU connection from the contact on the fan relay and connect the new circuit to the same contact on the fan relay. That will make the deign simpler.

If you agree with this approach I will need to know how the ECU drives the relay;
(1) is one end of the relay coil connected to 0V and does the ECU output a high voltage to operate the relay or
(2) is one end of the relay coil connected to 12V and does the ECU output a low voltage to operate the relay

I will also need to know what the relay coil resistance is (you can measure this with a multimeter).

if you have trouble understanding what I am asking please ask.

In general terms do you have access to electronic part suppliers and could you assemble a simple circuit.

Do you have:
soldering iron
solder
small pliers
small wire cutters
small screw driver
multimeter

Apologies for all the questions but the answers are required to make a sucess of this project.

spec

Click to expand...

The ECU drives the relay with (2) point you mentioned. Also the relay coil resistance is written like "DC 12V - 30Amps". I got all the neccessary things like "soldering iron, solder,......" you mentioned. The relay got 4 pins "30,85,86,87"

Thanks

That's good.

To give you an idea of what the circuit involves, below is a sketch (not the final circuit). Would you be able to build a circuit like this?

spec

spec said:

That's good.

To give you an idea of what the circuit involves, below is a sketch (not the final circuit). Would you be able to build a circuit like this?

spec

View attachment 101635​

​

Click to expand...

I can do it if I get the values

pradoartz said:

I can do it if I get the values

Click to expand...

Excellent that you can make the circuit. I will post a proper schematic for the fan controller, with all the component values

Thanks for the information about the temperature setting for the fan to operate. The circuit will have two variable resistors. One variable resistor will set the fan on temperature (top left on the sketch) and one variable resistor will set the off temperature. So you can set the two temperatures how you like. I will design the circuit to use a new relay

(1) Would you be able to solder a surface mount (very small) operational amplifier or would you be happier with a through hole (bigger) operational amplifier

(2) One last question: will the fan controller have 12V applied to it all the time, even when the engine is not running? Or will the fan controller be turned off when the ignition switch is turned off?

Once again, sorry for all the questions.

spec

spec said:

Excellent that you can make the circuit. I will post a proper schematic for the fan controller, with all the component values

Thanks for the information about the temperature setting for the fan to operate. The circuit will have two variable resistors. One variable resistor will set the fan on temperature (top left on the sketch) and one variable resistor will set the off temperature. So you can set the two temperatures how you like. I will design the circuit to use a new relay

(1) Would you be able to solder a surface mount (very small) operational amplifier or would you be happier with a through hole (bigger) operational amplifier

(2) One last question: will the fan controller have 12V applied to it all the time, even when the engine is not running? Or will the fan controller be turned off when the ignition switch is turned off?

Once again, sorry for all the questions.

spec

Click to expand...

Surface mount op amp is very tough to me. So I prefer some bigger components.

The circuit will not get power when ignition is in OFF position.

----------&&----------

But if it's necessary to use surface mount op amp to operate compulsory means I can solders done through some professionals here.


Thanks

POST ISSUE 21 of 2016_10_21

Hi pradoartz,

Below is a schematic of the proposed motorcycle fan controller (MFC).


ERRATA
(1) Please note the following changes:
(1.1) Relay coil snubbing (thanks Diver300)
(1.2) Relay contacts snubbing (thanks Diver300)
(1.3) 470 Ohm, 1 Watt minimum resistor added to circuit
(1.4) 2.2 Ohm, 5 Watt minimum, resistor added to circuit
(2) Change '1N4002 thru 1N4007' to '1N4007'
(3) Change 'TIP42B or TIP42C' to 'TIP42C'
(4) Change LM393 to LM2903 (better temperature range)

NOTES
(1) The LM2903 dual comparator is available in a DIL8 plastic package, so construction will be easier than for a surface-mount package
(2) Special care must be taken to ensure that the MFC is not heated by the motorcycle engine. The surface temperature of the MFC should not be over 80 Deg C
(3) Special care must be taken to ensure that the MFC does not get wet. Even dampness and condensation will adversely affect the MFC operation
(4) The LM2903 comprises two comparators in one case. Only one comparator is used, but the other comparator must be connected as shown on the schematic.
(5) RV1 sets the fan turn-on temperature.
(6) R6 defines the hysteresis of the Schmidt trigger (N1A). With the value shown the hysteresis will be 5 Deg C. Thus, if the fan turn-on temperature were set to 80 deg C, the fan would turn on at 80 Deg C and would not turn off until the water temperature had dropped to 75 Deg C.
(7) When the relay is not energized (and the fan is off) the circuit only consumes around 1.7 mA, so the MFC can be left connected to the battery when the motorcycle alternator is not charging. Note that it is better for your motorcycle for the fan to be operational when the engine stops and the motorcycle is stationary because the water or oil still need to be cooled. Once the liquid is 5 Deg C delow the fan-on temperature the MCFC will turn the fan off.
(8) Wire must be high temperature automotive grade.

DATA SHEETS & SOURCES
(1) Comparator dual: LM2903: https://www.ti.com/lit/ds/symlink/lm2903-n.pdf
(2) Power transistor: TIP 42C: https://www.onsemi.com/pub_link/Collateral/TIP41A-D.PDF
(3) Relay: Single pole, single throw (SPST), automotive type. Coil, 12V, 80 Ohms. Contacts, 30A minimum. Single Pole Double Throw (SPDT) will also be suitable.
(4) Potentiometer: 50K, pre-set, multi-turn
(5) Diode: 1N4002 to 1N4007.
https://www.vishay.com/docs/88503/1n4001.pdf
(6) Diode: VSB1545_M3, 25V min, 10A min:
**broken link removed**
https://www.digikey.co.uk/product-d...on/VSB1545-M3-54/VSB1545-M3-54GICT-ND/4810661
(7) Capacitor: aluminum electrolytic, high ripple current, high temperature, 470uF, 25V minimum
(8) Capacitor: disk ceramic, or multi-layer, 100nF, 50V minimum, X7R dielectric, through-hole (not surface mount)
(9) Resistor: all resistors, unless otherwise stated, are metal film, or metal oxide (not carbon), through hole (not surface mount), 250mW minimum, 5% or better
(10) Fuse: FS1 is a 10A automotive type (as I do not know the characteristics of the fan, 10A is only an estimate)

BILL OF MATERIALS (BOM)

6t

spec said:

POST ISSUE 01 of 2016_10_17

*** WORK IN PROGRESS ***

Hi pradoartz,

Below is a schematic of the proposed motorcycle fan controller (MFC).



NOTES
(1) The LM393 dual comparator is avail able in a DIL8 plastic package so construction will be easier than for a surface-mount package


DATA SHEETS & SOURCES
(1) LM393: https://www.ti.com/lit/ds/symlink/lm2903-n.pdf
(2) TIP 42x: https://www.onsemi.com/pub_link/Collateral/TIP41A-D.PDF
(3) Relay: Single pole, single throw automotive type. Coil, 12V, 80 Ohms. Contacts 30A minimum
(4) Potentiometer: 50K
(5) Diode 1N400x, 50V min
(6) Diode ??? 10A, 50V min
(7) Capacitor aluminum electrolytic, high ripple, high temperature, 470uF, 25V minimum

Click to expand...

6th diode????

please wait until I have completed post #26.

Thanks

spec

spec said:

please wait until I have completed post #26.

Thanks

spec

Click to expand...

Sure sure. I am so excited to see the circuit. Haha.

pradoartz said:

Sure sure. I am so excited to see the circuit. Haha.

Click to expand...

No probs.

spec

spec said:

POST ISSUE 04 of 2016_10_17

*** WORK IN PROGRESS ***

Hi pradoartz,

Below is a schematic of the proposed motorcycle fan controller (MFC).



NOTES
(1) The LM393 dual comparator is available in a DIL8 plastic package so construction will be easier than for a surface-mount package
(2) Special care must be taken to ensure that the MFC is not heated by the engine. The surface temperature of the MFC should not be over 80 Deg C
(3) The LM393 comprises two comparators in one case. Only one comparator is used but the other comparator must be connected as shown on the schematic.


DATA SHEETS & SOURCES
(1) LM393: https://www.ti.com/lit/ds/symlink/lm2903-n.pdf
(2) TIP 42x: https://www.onsemi.com/pub_link/Collateral/TIP41A-D.PDF
(3) Relay: Single pole, single throw automotive type. Coil, 12V, 80 Ohms. Contacts 30A minimum
(4) Potentiometer: 50K
(5) Diode 1N400x, 25V min
(6) Diode STPS10L25D, 25V min **broken link removed**
https://www.digikey.co.uk/product-detail/en/stmicroelectronics/STPS10L25D/497-2738-5-ND/603763
(7) Capacitor aluminum electrolytic, high ripple, high temperature, 470uF, 25V minimum
(8) Capacitor disk ceramic 100nF 25V minimum. X7R dielectric
(9) Resistor: all resistors, unless otherwise stated, metal film, or metal oxide, through hole (not surface mount) 250mW minimum, 5% or better

Click to expand...

All resistors??

https://www.electroncomponents.com/Group-resistor-1_4watts?filter_name=Resistor

pradoartz said:

All resistors??

https://www.electroncomponents.com/Group-resistor-1_4watts?filter_name=Resistor

Click to expand...

I think those resistors are carbon, which are not the best. You need metal film or metal oxide.

spec

Thanks for the schematic bro

spec said:

POST ISSUE 11 of 2016_10_18

Hi pradoartz,

Below is a schematic of the proposed motorcycle fan controller (MFC).

**broken link removed**​

ERRATA
(1)

NOTES
(1) The LM393 dual comparator is available in a DIL8 plastic package, so construction will be easier than for a surface-mount package
(2) Special care must be taken to ensure that the MFC is not heated by the motorcycle engine. The surface temperature of the MFC should not be over 80 Deg C
(3) Special care must be taken to ensure that the MFC does not get wet. Even dampness and condensation will adversely affect the MFC operation
(4) The LM393 comprises two comparators in one case. Only one comparator is used, but the other comparator must be connected as shown on the schematic.
(5) RV1 sets the fan turn-on temperature.
(6) R6 sets the hysteresis of the schmitt trigger (N1A). With the value shown the hysteresis will be 5 Deg C. Thus, if the fan turn-on temperature were set to 80 deg C, the fan would turn on at 80 Deg C and would not turn off until the water temperature had dropped to 75 Deg C.
(7) When the relay is not energized (and the fan is off) the circuit only consumes around 1.7 mA, so the MFC can be left connected to the battery when the motorcycle alternator is not charging.
(8) Wire must be high temperature automotive grade.

DATA SHEETS & SOURCES
(1) Comparator dual: LM393: https://www.ti.com/lit/ds/symlink/lm2903-n.pdf
(2) power transistor: TIP 42x: https://www.onsemi.com/pub_link/Collateral/TIP41A-D.PDF
(3) Relay: Single pole, single throw, automotive type. Coil, 12V, 80 Ohms. Contacts, 30A minimum
(4) Potentiometer: 50K, pre-set, multi-turn
(5) Diode: 1N400x, 25V min_500mA min.
https://www.vishay.com/docs/88503/1n4001.pdf
(6) Diode: VSB1545_M3, 25V min, 10A min:
**broken link removed**
https://www.digikey.co.uk/product-d...on/VSB1545-M3-54/VSB1545-M3-54GICT-ND/4810661
(7) Capacitor: aluminum electrolytic, high ripple current, high temperature, 470uF, 25V minimum
(8) Capacitor: disk ceramic, 100nF, 25V minimum, X7R dielectric (not surface mount)
(9) Resistor: all resistors, unless otherwise stated, are metal film, or metal oxide (not carbon), through hole (not surface mount), 250mW minimum, 5% or better
(10) Fuse: FS1 is a 10A automotive type

Click to expand...

You are a GENIUS bro.

R13 is the variable resistor right? I mean R13 is the coolant temperature sensor ?
If so, Resistance from the r13 varies from 1.3K ohm(engine is cool ~ 25°C) to 0.1k ohm(engine is too hot ~ 110°C). So the schematic you designed will kick the relay exactly by 80°C (~0.3k ohm) right?

For your reference.
------------------------------

pradoartz said:

Thanks for the schematic bro

Click to expand...

No probs- I hope the circuit works OK

pradoartz said:

... R13 is the coolant temperature sensor ?
If so, Resistance from the r13 varies from 1.3K ohm(engine is cool ~ 25°C) to 0.1k ohm(engine is too hot ~ 110°C). So the schematic you designed will kick the relay exactly by 80°C (~0.3k ohm) right?

Click to expand...

Yes that is exactly right: R13 is the temperature sensor.

You can set the fan turn-on-point to whatever temperature you like, including 80 Deg C, by adjusting the potentiometer (RV1). Note that at 80 Deg C the nominal value of the temperature sensor is 319 Ohms, as indicated in brackets on the post #26 schematic.

Don't worry, I based the design, of the circuit in post #26, on the characteristics of the temperature sensor that were in your original post.

spec

spec said:

POST ISSUE 14 of 2016_10_18

Hi pradoartz,

Below is a schematic of the proposed motorcycle fan controller (MFC).

**broken link removed**​

ERRATA
(1)

NOTES
(1) The LM393 dual comparator is available in a DIL8 plastic package, so construction will be easier than for a surface-mount package
(2) Special care must be taken to ensure that the MFC is not heated by the motorcycle engine. The surface temperature of the MFC should not be over 80 Deg C
(3) Special care must be taken to ensure that the MFC does not get wet. Even dampness and condensation will adversely affect the MFC operation
(4) The LM393 comprises two comparators in one case. Only one comparator is used, but the other comparator must be connected as shown on the schematic.
(5) RV1 sets the fan turn-on temperature.
(6) R6 defines the hysteresis of the schmitt trigger (N1A). With the value shown the hysteresis will be 5 Deg C. Thus, if the fan turn-on temperature were set to 80 deg C, the fan would turn on at 80 Deg C and would not turn off until the water temperature had dropped to 75 Deg C.
(7) When the relay is not energized (and the fan is off) the circuit only consumes around 1.7 mA, so the MFC can be left connected to the battery when the motorcycle alternator is not charging. Note that it is better for your motorcycle for the fan to be operational when the engine stops and the motorcycle is stationary because the water or oil still need to be cooled. Once the liquid is 5 Deg C delow the fan-on temperature the MCFC will turn the fan off.
(8) Wire must be high temperature automotive grade.

DATA SHEETS & SOURCES
(1) Comparator dual: LM393: https://www.ti.com/lit/ds/symlink/lm2903-n.pdf
(2) power transistor: TIP 42x: https://www.onsemi.com/pub_link/Collateral/TIP41A-D.PDF
(3) Relay: Single pole, single throw, automotive type. Coil, 12V, 80 Ohms. Contacts, 30A minimum
(4) Potentiometer: 50K, pre-set, multi-turn
(5) Diode: 1N400x, 25V min_500mA min.
https://www.vishay.com/docs/88503/1n4001.pdf
(6) Diode: VSB1545_M3, 25V min, 10A min:
**broken link removed**
https://www.digikey.co.uk/product-d...on/VSB1545-M3-54/VSB1545-M3-54GICT-ND/4810661
(7) Capacitor: aluminum electrolytic, high ripple current, high temperature, 470uF, 25V minimum
(8) Capacitor: disk ceramic, 100nF, 25V minimum, X7R dielectric (not surface mount)
(9) Resistor: all resistors, unless otherwise stated, are metal film, or metal oxide (not carbon), through hole (not surface mount), 250mW minimum, 5% or better
(10) Fuse: FS1 is a 10A automotive type

Click to expand...

Thank you bro, now i am collecting the required component one by one. Here in Chennai i am not able to get all the components. so i ordered online for a few components. Will definitely post you an update after i done assembling the circuit.

pradoartz said:

Thank you bro, now i am collecting the required component one by one. Here in Chennai i am not able to get all the components. so i ordered online for a few components. Will definitely post you an update after i done assembling the circuit.

Click to expand...

Hi pradoartz,

No sweat.

The circuit is pretty straight-forward and uses freely available low-cost components and well-established design techniques.

Hopefully, it should be fairly robust too.

Yes, do let us know how the circuit turns out. Also a picture of the circuit and your bike would be interesting.

spec

spec said:

Hi pradoartz,

No sweat.

The circuit is pretty straight forward and uses freely available low-cost components and well-established design techniques.

Yes, do let us know how the circuit turns out. Also a picture of the circuit and your bike would be interesting.

spec

Click to expand...

Have you tested this circuit in any schematic simulator software?

How you guys have so much brain, like you are developing a professional schematic in no time. You are awesome bro.
What do you do? Are you an electrical & electronic engineer ?

and

About the pictures they are coming as soon as i assembled

N1A, N1B ARE DIFFERENT ?

pradoartz said:

Have you tested this circuit in any schematic simulator software?

Click to expand...

No- I do not use simulators except for complex logic circuits. I analyzed the circuit and made the necessary calculations.

pradoartz said:

How you guys have so much brain, like you are developing a professional schematic in no time. You are awesome bro.

Click to expand...

Thanks- I am blushing. Once you know the techniques, designing a circuit like that is reasonably simple. Things always seem clever for people in fields you are not conversant with. To me a plasterer is awesome, or a painter, or a musician.

pradoartz said:

What do you do? Are you an electrical & electronic engineer ?

Click to expand...

Yes- electronics design engineer for years but, apart from consultancy, retired.

pradoartz said:

About the pictures they are coming as soon as i assembled

Click to expand...

Look forward to seeing the pictures. Some of us on ETO are motorcycle nuts.

spec