Re: Mercedes fan upgrade
[Re: DaveRS23]
#838210
10/27/10 11:04 PM
10/27/10 11:04 PM
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Joined: Feb 2003
Posts: 8,761
Andrewh
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for that I would just build in a second signal to the controler. Again if one is on, it goes to low, if both are on, it goes to high. you have 2 temp sensors and 2 relay's. Still easier than figuring out the sensor outputs.
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Re: Mercedes fan upgrade
[Re: Andrewh]
#838211
10/28/10 01:40 AM
10/28/10 01:40 AM
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Joined: Oct 2007
Posts: 3,933 Oregon
hooziewhatsit
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I'll have to see what I can come up with. I'm in the middle of a plumbing emergency at the moment ( ), so it may be a day or two until I can really look at it. I have that temp sensor from Summit coming, and I think I have enough other stuff laying around to get started on it. I'll post an update once I have more info
If you ever find yourself in a fair fight, your tactics suck.
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Re: Mercedes fan upgrade
[Re: hooziewhatsit]
#838212
10/28/10 01:48 AM
10/28/10 01:48 AM
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Joined: Jan 2003
Posts: 1,476
gtx69
super gas
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super gas
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Re: Mercedes fan upgrade
[Re: gtx69]
#838213
10/28/10 01:44 PM
10/28/10 01:44 PM
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Joined: Nov 2004
Posts: 7,274 s.w.fl
bonefish
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Quote:
My you are the man.What are the costs going to be?We do need a controller for that fan.I myself never adjust my fan.What the point in it.I want full speed.But i can live with whatever the group wants.I just want it to last.
please keep it in this thread so ill recieve an update in my subscribed threads.TANKS,AJ
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Re: Mercedes fan upgrade
[Re: 451Mopar]
#838217
10/29/10 04:54 PM
10/29/10 04:54 PM
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Joined: Jan 2003
Posts: 28,096 Irving, TX
feets
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I'm not sure how the controller works. Andrewh was playing with lower voltage to the trigger on his fan and it seemed to run slower. I have not tried that on the hot rod.
PWM may or may not work on this setup. There's something different about this fan. Putting direct current on the windings resulted in a fan that shuddered back and forth. It would not spin in complete revolutions.
The new style and old style fans are interchangeable on the Mercedes. They operate with the same input but the newer version runs at 90% with a constant 12 volts to teh trigger.
We are brothers and sisters doing time on the planet for better or worse. I'll take the better, if you don't mind. - Stu Harmon
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Re: Mercedes fan upgrade
[Re: feets]
#838218
10/29/10 05:49 PM
10/29/10 05:49 PM
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Joined: Oct 2007
Posts: 3,933 Oregon
hooziewhatsit
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Assuming that they used a brushless fan. http://en.wikipedia.org/wiki/Brushless_DC_electric_motorBasically, you apply power to one set of windings, which moves the fan a little, then you move power to the next set. Repeat in a rapid fashion, and the fan turns. Applying power to one set of windings isn't enough to make it turn. The controller on the mercedes fan may be smart enough to take a lower constant voltage and generate the correct speed. That's effectively the same thing as using a PWM to reduce the average voltage without using a resistor. I still think it would be best to generate a PWM to control it, matching what the factory does. From a purely design aspect, it's much easier and cheaper to make the ECU generate a PWM in software, than to add DAC hardware (Digital to analog converter) to produce a variable voltage. Oh yea; I was planning on having it powered from a switched 12v supply (the controller will only draw ~60mA). Or, it can have a switched and a constant 12v in, so it can continue to run the fan after shutdown. Thoughts? Or, too many options, just make it already
If you ever find yourself in a fair fight, your tactics suck.
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Re: Mercedes fan upgrade
[Re: hooziewhatsit]
#838219
10/29/10 06:20 PM
10/29/10 06:20 PM
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Joined: Jan 2003
Posts: 28,096 Irving, TX
feets
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Quote:
Assuming that they used a brushless fan. http://en.wikipedia.org/wiki/Brushless_DC_electric_motor
Basically, you apply power to one set of windings, which moves the fan a little, then you move power to the next set. Repeat in a rapid fashion, and the fan turns. Applying power to one set of windings isn't enough to make it turn.
That's pretty much what I was thinking. I did a little digging on PWM and brushless motors while troubleshooting in the original thread. Unfortunately, I kept getting computer fan motors in my searches. My Google-Fu is weak.
We are brothers and sisters doing time on the planet for better or worse. I'll take the better, if you don't mind. - Stu Harmon
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Re: Mercedes fan upgrade
[Re: Andrewh]
#838221
10/29/10 06:24 PM
10/29/10 06:24 PM
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Joined: Jan 2003
Posts: 28,096 Irving, TX
feets
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I say let the end user determine if they want to use that function. It will allow a manual override if deemed necessary.
Yes, it will eat a battery quickly with a 39 amp draw.
We are brothers and sisters doing time on the planet for better or worse. I'll take the better, if you don't mind. - Stu Harmon
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Re: Mercedes fan upgrade
[Re: feets]
#838222
11/01/10 04:31 PM
11/01/10 04:31 PM
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Joined: Oct 2007
Posts: 3,933 Oregon
hooziewhatsit
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Done! Well, not quite, but the basic blocks are there. I took a video of an LED being dimmed by a PWM according to a variable resistance input, but it's pretty poor quality, so I won't bother posting it. Now for the fun stuff. Below is a description of what I plan to build. Before anyone asks, the difference between a 'simple' controller, and an adjustable/variable one, is a couple of potentiometers and some code; ie, very little additional cost in more hardware. Inputs: 12v switched ground temperature sensor AC on/off Outputs: PWM Trigger wire to fan Power led Output that can drive an LED in the cab to show fan status. Status LED on the controller (indicate temp sensor not found, etc) Settings: 2 potentiometers (variable resistors). - Turn on temperature - Full speed temperature Each has a labeled temperature range. Functionality: At the turn on temp, the fan will turn on to 60%. It will increase linearly to 90% on at the high speed temp. As the temp drops, so will the fan speed, potentially below the turn on temp, when it will turn off again. It will go several degrees below the turn on temperature to avoid rapid on/off at the turn on point. When AC input is high, fan will go to 90%, after a 15 second delay. After the signal turns off, the fan will continue at full speed for 30 seconds. If input pots are set to non-logical state, the fan will always be at 90%. If the temp sensor is not detected, the fan will always be at 90%, after a short delay on startup. Screw terminals for all input/output wires (18awg). At this point, it won't be completely sealed from water, but the board will be sprayed to protect it from occasional splashes. Just don't hose it down Currently aiming for a price around $50, without a temp sensor from Summit (I'll provide links to the sensor(s) I recommend). Anything else? *Edited to add/clarify features
Last edited by hooziewhatsit; 11/01/10 06:38 PM.
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Re: Mercedes fan upgrade
[Re: Andrewh]
#838225
11/01/10 06:31 PM
11/01/10 06:31 PM
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Joined: Oct 2007
Posts: 3,933 Oregon
hooziewhatsit
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I'm currently planning on using this temp sensor because it's cheap, and it comes with adapters. http://www.summitracing.com/parts/ATM-2385/Although I like how this one has a separate ground, and comes with the pigtail. http://www.summitracing.com/parts/MSD-2310/I should be able to make the AC input work by either grounding or applying 12v to it A delay on AC turn on/off is easy as well. I need to research the trinary switch a little more... Quote:
If there is no temp signal when the key comes on you go to 90 percent?
Correct; I don't see any other way to do it. It would basically act as a failsafe; fan always on. I can add a short delay as well, so it doesn't come on as the key goes through ACC to start.
Feets has a fan on the way to me I'll test it with extensively, then I'll send a controller back to feets for him to test.
I'm still aiming for an end cost of ~$50ish, probably without the linked temp sensor.
Quote:
oh, and the led if nice, but I guarantee you can hear that fan when it comes on. you will know.
Heh, true It's an easy feature to add though
If you ever find yourself in a fair fight, your tactics suck.
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Re: Mercedes fan upgrade
[Re: Andrewh]
#838227
11/01/10 07:00 PM
11/01/10 07:00 PM
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Joined: Oct 2007
Posts: 3,933 Oregon
hooziewhatsit
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Quote:
hmm since his isn't running, it may come to me to test anyway.
can you set the temp thing as a simple signal as well? ground or 12 volts to 90 instead of just no signal. and the rest as you described? don't want to have to rewire too much.
trinary is pretty simple. it has the high low pressure switch for the a/c compressor, and has another high/low pressure switch to give an electric fan a signal. basically just passes current when it hits the high and opens when it hits the low.
Ok, you or him, doesn't matter to me.
Yea, I can make it work like that, likely by grounding the sensor input (I'll be sure once the design is done). I think I still want to detect no sensor, but having an option to not install the sensor is a good idea as well.
If you ever find yourself in a fair fight, your tactics suck.
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Re: Mercedes fan upgrade
[Re: Andrewh]
#838229
11/01/10 07:35 PM
11/01/10 07:35 PM
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Joined: Jan 2003
Posts: 1,476
gtx69
super gas
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super gas
Joined: Jan 2003
Posts: 1,476
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