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Setting up PWM control for water pump / fans

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I am looking into setting up PWM control for a number of fans and water pump for my car and is trying to figure out the wiring side of things. I know the general approach would be to drive a solid state relay using a PWM output on the G4+ and use the PWM duty cycle to control the effective voltage so I though simply wring a PWM output from the relay would do the job.

However, the more research I do the more I am confused. Searching online I have found diagrams from haltech and adaptronic where both had a similar setup. Both diagram had a 1K pull up resistor connected in parallel to the input side and haltech warned that damage would occur if the resistor is not installed. The adaptronic diagram also what looked like a freewheeling diode but it is connected in parallel to the output side (you shouldn't need one even if it is on the output side since there are no coils to drive in a SSR anyway).

I cannot figure out what is the purpose of that 1K resistor nor the diode on the outside. What exactly are their purpose?

Also, both diagram had prescribed specific outputs to use for this purpose and warned that damage may occur if any other outputs are used. Will that be the case for G4+?

Thank you!

 

http://www.adaptronic.com.au/forum/index.php?topic=6106.0

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The 1K resistor and the Diode only apply to standard coil relays, use an SSR with the correct capacity to PWM direct from the Link ECU.

The Link G4+ ECU already has protection built in to the AUX outputs so can drive a normal relay or solenoid without additional diodes. 

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Also a bit of further info, Clint's comment about the resistor is not required on the input side is correct (Our ECU's have a built in pull up on the aux output so it is not needed).  The Diode on the output side may be needed depending on what SSR you use.  Many of the cheap ones need the diode as they arent designed to drive inductive loads, the flyback voltage will fry them in no time.  The diode is there to capture the flyback.  Look at the datasheet for the SSR you want to use and if it states it is suitable for inductive or motor loads then no diode is needed.  If it states suitable for resistive/lamp/heater loads only then you will need a Diode.

Here is the datasheet for the one Haltech sell (diode needed):

cvEkk5P.png

 

Here is an example Hella SSR I have used a few times (no diode needed):

j544qFR.png

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21 hours ago, mapper said:

A problem i found on the hella one is, it is ground switched and the ECU switch to ground when its off. Means pump start to run when ECu is turned off. 

 

that sounds like the +12v to the coil was not switched.

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There is no +12V connected to the coil on a Solid state Relay.  Load side was +12V direct from BAT. I ended up to disrupt signal to ECU with a conventional Relay. Because live time of Relay...

What I was thinking about is if the SSD Relay cab be manipulated with a diode or Pullup or similary in signal line. 

 

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11 minutes ago, Brad Burnett said:

that sounds like the +12v to the coil was not switched.

No the coil + (86) is bound internally to the input from the battery (30) .

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2 minutes ago, ClintBHP said:

No the coil + (86) is bound internally to the input from the battery (30) .

no, the problem is the Hella solid state relay is switched on when both control terminals are switched to ground. Thats due to the internal working of a SSD. 

Means to turn the SSD Relais off, the control input must have no electric connection (ECU-Relay wire disrupted) or +12V connected. 

The problem is that the AUX output of the Link ECU is switched to ground when ECU is off. 

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30 minutes ago, mapper said:

no, the problem is the Hella solid state relay is switched on when both control terminals are switched to ground. Thats due to the internal working of a SSD. 

Means to turn the SSD Relais off, the control input must have no electric connection (ECU-Relay wire disrupted) or +12V connected. 

The problem is that the AUX output of the Link ECU is switched to ground when ECU is off. 

On the Hella SSD relays the positive side of the trigger is hard wired to +14v input pin. As I said above if you were to compare it to a 'normal' relay, the coil + (86) is bound internally to the input from the battery (30) So the behaviour you see is exactly what happens.

Link require you have a ignition switched positive side of the relay coil, which is not possible with this particular SSD relay.

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Think we are talking about the same. "hardwired" is a simple term to descript the internal function of a SSD Relay. In fact there is a Mosfet transistor or thyristor inside the SSD and the internal connection are electrons which diffuse between the gates (n-p-n) in the semiconductor material. 

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48 minutes ago, Adamw said:

They work fine wired in the normal manner if you connect to an ignition aux rather than a normal aux.

Not sure, can aux ign be set as a gp PWM table? 

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On ‎3‎/‎02‎/‎2018 at 12:11 PM, mapper said:

Not sure, can aux ign be set as a gp PWM table? 

True, I have only used these SSR's for fuel pump control and you can assign FP speed to an ign aux.  For fans, water pump , GP PWM the live supply side of the SSR will have to come from a switched 12V source.

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56 minutes ago, Adamw said:

True, I have only used these SSR's for fuel pump control and you can assign FP speed to an ign aux.  For fans, water pump , GP PWM the live supply side of the SSR will have to come from a switched 12V source.

Or switch PWM Signal with a relay. Means less load on the relay. 

Thank you for the answer. Would it be possible to add GP PWM to Aux and Fuel output in a future release? or are there hardware limitations? 

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On 02/02/2018 at 10:03 PM, mapper said:

Think we are talking about the same. "hardwired" is a simple term to descript the internal function of a SSD Relay. In fact there is a Mosfet transistor or thyristor inside the SSD and the internal connection are electrons which diffuse between the gates (n-p-n) in the semiconductor material. 

I don't see this problem on the SSD's we use here (the ETA ones), UNLESS the Supply which should be on pin (30) is connected to the output pin (87).

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4 hours ago, ClintBHP said:

I don't see this problem on the SSD's we use here (the ETA ones), UNLESS the Supply which should be on pin (30) is connected to the output pin (87).

Okay, good to know. Do you have a part number for ones you use? 

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We use the ESR 10 Series, we also found they are so fast that you can double them up if you need more amps and they shut down if over current so if one fails no issue, we have not had one fail yet.

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Sorry, its been a long while. I've finally started to re-wire everything in my car and setup the PWM control at the same time.

This is the solid state relay that I've ended up getting:

http://hellahd.com/files/5113/4444/9719/H41773001 Data Sheet.pdf

It's a Hella unit that looked extremely to the ones you get from NZ/Australia but seems like it is not designed for inductive loads.

After doing some research on fly-back diodes, seems like a Schottky diode would work best for our application for its fast response. Looking at the specs, I think the diodes below should be sufficient for my purpose? Should the voltage rating of 120V be a concern as I've seen Adam recommending elsewhere the use of 1N4004 which are rated to 400V.

https://www.mouser.com/ProductDetail/Vishay-Semiconductors/V30120CI-M3-P?qs=F5EMLAvA7IDciT4dWs6BgQ%3D%3D

https://www.mouser.com/ProductDetail/Vishay-Semiconductors/V40120CI-M3-P?qs=F5EMLAvA7IC2Rt1XtcaKGQ%3D%3D

 

Thank you!

 

Best regards,

Jerry Ip

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