Heater Fan

[Lebro]

Thanks guys, I have just ordered the one above, which I prefer to the previous one A - because the previous one is out of stock, & B - this one is enclosed in a case.

I don't think you need a switch, as it regulates the output down to 0% power out.

I would wire it through the ignition circuits (as before) so no current drawn when ign off.

Bob.

[RogerH]

Hi Bob,

I didn't realise that on the minimum setting it is effectively in the OFF mode.  If this is correct then that would save a little effort.

I'll give it a try and report back.

I'm just in the middle of taking the egnie out to fit the GB and popping it back in this afternoon.  I may be testing the fan tomorrow.

 

Roger

[Lebro]

Roger. This is the one you ordered, it also goes down to "off":

 

Specifications:

Working Voltage: DC 6V - DC 90V

Control Power: 0.01 - 1000W (Maximum current 15A)

Static Current: 0.005 A ( Standby )

PWM Duty Cycle: 0% -100%                                <--------------------------------

PWM Frequency: 15 KHz

Size (L x W x H ): Approx. 64 x 59 x 30 mm

[Andy Moltu]

I suppose having the feel of a click in the off position may be nice as it may be difficult to know if it is off when knob twiddling in the dark so would feel like the dimmer.

[AndyR100]

Ok, getting to the end of this one now......

i closed up the airbox including resealing and new mounts for the scuttle fastenings.

it took a little longer to get the scuttle fasteners done up, but got there in the end without too much cursing.

i did some test wiring setup using my PWM/Potentiometer - the SPAL fan was happy to be controlled by the PWM, unfortunately with the PWM the fan ran at a slower speed. This could be a problem with my Controller, or the supplied pot could have been. 0-80 rather than 0-100, either way the output from the controller wasn’t the full 12V. It will be interesting to know if any of the alternative controller/pot combinations found by others do let the fan run at full-chat. I have read that voltage drop is not unusual with PWM’s (shame I didn’t read before I bought one  ) 

For now I have hooked it up via the original switch so it is either on or off. As mentioned before I have run a fresh 12v supply from a dedicated ignition-switched aux fusebox - probably not absolutely necessary, but isn’t going to do any harm and move some load of the old loom/fuse box.

For anyone wanting more puff without hacking the airbox around (apart from drilling 4 fan-mounting holes), buying an expensive alternative or digging too deep into the piggy bank it can be done as I’ve described - I’ll leave variable speed for another day (I have left the wiring in a state where I can plumb in an alternative controller very easily.

Thank you for all of the pointers and suggestions along the way, I am grateful for them all, hopefully this thread will be of help to others who may wish to try something similar in the future. 

....... Andy 

........ Andy 

Edited June 7, 2020 by AndyR100

[RogerH]

Hi Andy,

thanks for that. I also didn;t realise that it would not got to 100%.

I'm sure there is an answer

 

Roger

[Lebro]

These speed controllers use mosfet transistors, switched on & off very quickly to provide an average output variable between 0 & 100%. When at 100% the mosfet is permanently switched on  buy they do have a resistance, usually very low (in the order of 0.1 ohm or less) that, combined with the resistance of the extra wiring, the circuit board tracks etc can add up to a resistance which can drop the eventual output voltage when driving any sort of load.  Measurement of voltages through the system would reveal where the losses are. Solutions are: use a lower Rds mosfet , use heavier gauge wiring, add wires on top of pub tracks.

Edited June 7, 2020 by Lebro

[AndyR100]

39 minutes ago, RogerH said:

Hi Andy,

thanks for that. I also didn;t realise that it would not got to 100%.

I'm sure there is an answer

 

Roger

Neither did i   .... i’d recommend you check the fan speed with/without your pwm/pot connected to avoid possible disappointment - you may be fortunate and your pwm pumps out the full-fat voltage.

there are options to investigate with boost buck converters, but that would probably need a step down and step up to retain polarity - I’ll save that for when I’m bored  -  it may be that one of the other pwm’s is better behaved.

.......Andy 

[RogerH]

Hi Andy,

I have been looking at a circuit to help

A 3 position switch. -

1 = 0ff

2 = medium speed through the PWM

3 = full power - this bypasses the PWM and gives 12V direct to the motor

 

I'll report back

 

Roger

[AndyR100]

10 minutes ago, Lebro said:

These speed controllers use mosfet transistors, switched on & off very quickly to provide an average output variable between 0 & 100%. When at 100% the mosfet is permanently switched on  buy they do have a resistance, usually very low (in the order of 0.1 ohm or less) that, combined with the resistance of the extra wiring, the circuit board tracks etc can add up to a resistance which can drop the eventual output voltage when driving any sort of load.  Measurement of voltages through the system would reveal where the losses are. Solutions are: use a lower Rds mosfet , use heavier gauge wiring, add wires on top of pub tracks.

 

Thanks Bob, 

I was aware that there was the potenial for a small drop-off, but even my ears could spot the slower fan-speed so it was much larger than I expected. Fingers crossed one of the other pwm’s that folk have found plays nicely.

......... Andy 

[AndyR100]

4 minutes ago, RogerH said:

Hi Andy,

I have been looking at a circuit to help

A 3 position switch. -

1 = 0ff

2 = medium speed through the PWM

3 = full power - this bypasses the PWM and gives 12V direct to the motor

 

I'll report back

 

Roger

Hi Roger

That sounds like a very elegant solution - please do keep me posted, thumbs up from me!  

........ Andy 

[RobH]

As Bob says there will be as slight voltage drop - should be less than 1volt  - because of the saturation resistance of the output transistor(s).  If it is greater than that there might be something preventing the unit reaching 100% duty cycle. Unfortunately you would really need an oscilloscope to find out whether that is the case. 

It's just possible the fan motor is a brushless type in which case there will be electronics inside it which might not like the fast switching from the PWM module. You could try putting a capacitor across the power feed to filter the spikes maybe something like 10 microfarads as a starter. 

Edited June 7, 2020 by RobH

[AndyR100]

1 hour ago, RobH said:

As Bob says there will be as slight voltage drop - should be less than 1volt  - because of the saturation resistance of the output transistor(s).  If it is greater than that there might be something preventing the unit reaching 100% duty cycle. Unfortunately you would really need an oscilloscope to find out whether that is the case. 

It's just possible the fan motor is a brushless type in which case there will be electronics inside it which might not like the fast switching from the PWM module. You could try putting a capacitor across the power feed to filter the spikes maybe something like 10 microfarads as a starter. 

Thanks Rob, 

Appreciate the suggestion to try a capacitor in series, this particular fan is brushed, although I guess there could be some kind of electrickery inside.

...... Andy 

Edited June 7, 2020 by AndyR100

[RobH]

In parallel Andy, not series but if the motor is a brush type I doubt it will help I'm afraid. 

[AndyR100]

2 minutes ago, RobH said:

In parallel Andy, not series but if the motor is a brush type I doubt it will help I'm afraid. 

Thanks!  Typing one thing and thinking another  

.......Andy 

[Lebro]

I have ordered on of the 2nd type of controller mentioned above, when it arrives I will check it out with a 'scope & report back

Bob.

[AndyR100]

15 minutes ago, Lebro said:

I have ordered on of the 2nd type of controller mentioned above, when it arrives I will check it out with a 'scope & report back

Bob.

Thanks Bob, that would be great

....... Andy 

[Andy Moltu]

Likewise I'm waiting for the controller to arrive.

However I do like Roger's suggestion of using a 2 speed swich that bipases the controller to give full power and the low speed setting controlled  by the pot via the controller.

Then you can use a 2 speed wiper motor switch with the correct knob on so would look original without the hassle of making the knob fit the pot or using a crappy radio knob.

[RogerH]

Hi Folks.

I have just tried my fan (Insitu) with and without the controller.

With the controller set at max there was X amount of puff.

Without the controller (wired direct) there was X  + Y puff.  Y = not a lot.

There was a very slight reduction.   However this is using only the car battery at just over 12V.  Running on 13.7V there will be a significant boot.

I'm sticking with the controller

I Like AndyM's idea of the wiper switch (3 position, 2 speed)  I will need to experiment to see the best way of wiring the controller.

 

Roger

[trevor]

Such an interesting topic and some seriously knowledgeable folk, this would make a great article for TR action !!

[Lebro]

Mine arrived today, so will do some checks later

Bob

[RogerH]

Hi Folks,

I was having a fiddle with the heater switch etc this morning.

A couple of issues.

1 - the two speed wiper switch; if used to give the heater fan two speeds has a 9/16" attachment. The original switch is 3/8". So the hole needs openeing.

2 -  The fast speed is no problem. Direct link througfh the switch to 12V. The 'other' speed needs to be sorted. I was thinking of a dropper resistor for simplicity.

        but then the grey cell clicked in - I have PWM supply.  So the second speed will go through this.

       Not sure how much current is going here and there so maybe a relay will be required .

 

More testing to be done.

 

Roger

[RogerH]

Doinmg some more fiddling and I have found that the little nut on the Pot of the PWM controller is cross threaded at the start of the thread on the pot.

I have tried cleaning it with a swiss file but not getting far. 

I thought about running a die down it but it is a very odd size.      0.268 OD (6.7mm) or there abouts    0.75mm/32 TPI 

My very inclusive list of thread sizes does not contain this one.  (I may have to become very inventive

Roger

 

PS - the nut was bu99ered. So I have made a sleeve to go over the original small thread and have fitted a 3/8 UNF nut.

Edited June 10, 2020 by RogerH

[RogerH]

Hi Folks,

slowly getting there.

The original motor took 4 amps to do its job.  The spec of the new motor is also 4 amps. 

So the ignition switch should be man enough for the new motor - nothing has changed.

This makes life a little easier.

The first pull of the switch will bring on the fast speed giving 12V direct to the fan,

The second pull disconnects the 12v direct to the fan and diverts it to the PWM controller. So this can be set at any speed.

Hopefully tomorrow I should have it all together and we will see what happens.

 

Roger

 

 

[AndyR100]

33 minutes ago, RogerH said:

 

The original motor took 4 amps to do its job.  The spec of the new motor is also 4 amps. 

So the ignition switch should be man enough for the new motor - nothing has changed.

 

Hey Roger,

glad you are making good progress.....  i reviewed the SPAL catalogue when I was sorting out the sizing, they state the current draw ranging from 5.5 to just under 7 amps, but when I tested mine it was drawing less than 4 amps so i’m pretty confident you’ll be good with the original feed .

Should work nicely incorporating the variable speed - nice job!

....... Andy

Edited June 10, 2020 by AndyR100