aGoGo

Hi all,

I would like to gether ideas about making a good efan setup. I am thinking using an fan from, ex. a Taurus or Fiero, and simply using a Microcontroller and relay to driving it, this way, the behavior of the efan can be programable or tunable (a port with a pot...), for instance, do not turn on or turn off in the first several minutes after starting or turning off the car, let the fan to kick in a bit early or late... at whatever temperature.

The things I am not quite sure now is, what's the best way to get the temperature reading, sensing the car is running or not and perhaps other things I am not aware of... More ideas about what should be implemented would be good as well.

The target cost for everything is couple dollar (under $5), and I will post the code and a simple tutorial if eveything goes good.

Please feel free to post your advise and ideas, thanks

thekyl

Humm i heard the best idea is go and buy a fan and controlor from an escort there the perfect size and lots higer output then most but I may be wrong.

DAVID GRIMES

Maybe just hook the fan up hot all the time and use a mechanical thermostat as a switch to turn it on or off depending on the temperature whether the car is running or not.

If it works, let me know and we can get a patent and make ( end of right pinky at side of mouth ) MILLIONS of Dollars !

Downside: If your tstat fails, you might come out one morning to find your efan was giving it hell for naught all night and your battery is dead. So, make sure to "code" it fail open circuit.

aGoGo

So, I will take it this way... There should be some failure proof mechnism, Ex. a kill switch or manual over ride...

BTW, can I sense voltage readings off a Tstate? If that how the efan car works? I thought about go for the oil temp (gauge) but not sure yet.

Keep it coming I need ideas!!!

jayroc

if you want to go efi, the megasquirt controller and relayboard setup can be configured to have the e-fan come on at certain temps at least. Requires some reprogramming, but not difficult from my understanding.

renns

Sounds like a neat project! Here's my thoughts:

Stick a coolant temperature sensor and potentiometer in series. Apply a reference voltage (5V) at one end, and ground the other. Use a micro with analog input capability to measure the voltage at the sensor-pot junction. Turn on output when threshold reached. Turn off when output drops some fixed value below threshold to prevent jittery operation at the transition. The pot can be adjusted to tweak the set point without reprogramming the micro.

If you are new to microcontrollers, or just want to whack something together quick, take a look at the Picaxe.

http://www.phanderson.com/picaxe/picaxe_overview.html

These are pic microcontrollers with a BASIC interpretter burned on the chip. They are dead simple to program (free programming software), low cost, and have the analog input capabilities you'll need.

You'll need to use a transistor to switch the relay, as the micro won't have the current source/sink capabilities directly.

If you scavenge the sensor and relay, the rest should come in under $10.00

Roger.

aGoGo

Now we are talking!

Is there a coolant temp sensor in a 12A, since it is running on wax clutch? If there is, please tell me about bit in detail.

The thresholding part, I would simply start with a 16F88 for now with a soft schmit trigger, perhaps eventially it would be a PID coutroller to optimize this thing. Great little chip BTW, and about little over a dollar, I am also thinking of finialize with those pic12s (couple cents). I have all I need on this part, chips, programmer...

Please tell me about coolant temp sensor, thanks

aGoGo

BTW, I am not trying to start a business, I would like to eventially contribute to a tutorial like the great rat's nest removal one. I see there are similarities in those two cases, as eliminating belts and load on our engine.

renns

Not sure on the 12A. There will be one sensor (side of rear iron below oil filter) driving the dash gauge, but leave that one alone. The second one, if it exists, is likely on the backside of the coolant pump, just beside the alternator. It's got a green plastic body, with a two-pin connector the same as is used for fuel injectors. It sounds like you are already up to speed with voltage divider circuits and associated calculations. If not, here's a link that'll cover the topic in long-winded fashion:

http://www.msefi.com/viewtopic.php?t=4734

Have fun,
Roger.

aGoGo

I am going to check the sensor now, BTW, it should be OK with 12V.

gsl-se addict

iTrader: (3)

The 12A uses a temperature switch in the back of the water pump housing instead of an actual coolant sensor. You should be able to swap in a coolant sensor off a GSL-SE or perhaps a second gen. The switch in the 12A is for the choke return. The switching point on the 12A is 158 (+/-) 11.8 degrees.

DAVID GRIMES

You have a Russian accent. You ain't from around here, are you ?

aGoGo

nope

aGoGo

nope , but I have been in the states for 7 years now

aGoGo

BTW, how was it accented?

aGoGo

BTW, how was it accented? Eh?

DAVID GRIMES

The phrasing. Just a shot in the dark.

aGoGo

now let's get back to the topic, efan controller?

DAVID GRIMES

Okay. It seems to me that the simplest and best way to have an efan is to get one with a temp sensor ( most have ) and wire it up live ( works based on temp whether or not the engine is on or not ). The sensor is the switch. Put a toggle in the loop if you feel the urge, but...

Exactly what are you hoping to accomplish ? What logic control can beat "on if above x degrees else off ?"

Read this on the Flex-a-lite Black Magic 150:

All Black Magic fans include an adjustable thermostat and a/c relay.
An optional manual override switch may also be ordered for water
crossings and/or mud racing. (#31148)
Part #
60, 150, 155, 165
Now available in Red Yellow Blue
w/Controls: 150(Black), 150R(Red), 150Y(Yellow), 150B(Blue)
wo/Controls: 155(Black), 155R(Red), 155Y(Yellow), 155B(Blue)
Restores horsepower by replacing the stock fan, where applicable. Extends water pump life and increases gas mileage. Allows greater control of fan operation; e.g. long idles, etc.
Features:
Strongest 15" electric fan available
Provides constant cooling, regardless of engine RPM
One piece, lightweight nylon shroud
Rigid bracket mounting system, no thru core mounting
High torque, high RPM electric motor
Built in control box with adjustable thermostat, A/C relay and manual switch connection
Installation instructions / wiring diagrams in English, French & Spanish ( sorry, No Russian ) Sorry, I couldn't resist

aGoGo

Where does this temp sensor or adjustable thermal stat usually installed?, I do even have temp sensors laying around (LM35), but I do not know what and how they are used in our cars. All I am trying to do is to figure out a cheap plan and go for efan. J yard efan = $20 and controller circuit = $5.

GSL-SE addict mentioned about swapping a coolant sensor from a SE, I think I'd like to know more about this. Would this be a straight drop in?

gsl-se addict

iTrader: (3)

It should be a direct drop in (I believe the threads are the same). The SE uses a temperature sensor in the back of the water pump housing just like the 12A cars have a temperature switch. You would then need to set up a circuit like Roger (renns) mentioned using either comparators or a micro-controller. If you switched, you would need something to control the choke if you have one. You could probably at to the e-fan circuit to control both the fan and the choke.

Kent

Directfreak

iTrader: (2)

Any Electric Fan will work the way you want it.
All you need is the Flex-a-lite VSC.



This is what I used on my car until very recently.

Operation:

One of the improvements of the Variable Speed Control is its soft-start feature that prevents the fans from drawing a large surge when they spin up. It's much less stress on the electrical system, especially with trucks using two large fans with a combined total of 5500 cubic feet per minute of flow!

- Also reducing stress on the electrical system, the VSC will not power up the fans for a 5 second delay after ignition.

- When the VSC starts the fans it powers them at 60% speed reducing noise and power draw. If the coolant temperature continues to rise, the VSC will increase fan speed gradually to 100% over the next 10 degrees beyond your calibration point.

- The air conditioner clutch will also activate the fans at 60% power unless coolant temperature is higher than the calibration point and the fans are already running at a higher speed.

- The VSC will continue to run the fans for up to 30 seconds after shutdown if the coolant temperature in the core is sufficient. (This feature will prevent post-shutdown boil-over in high-temperature applications.)

- The manual override ON input allows the fans to be turned on at 100% speed at any time, regardless of temperature or AC status, as long as the ignition is on. The engine does not have to be running. (This will be especially handy at the drag strip!)

- The manual override OFF input will prevent all other inputs from starting the fans. (The ability to disable the fans is a nice safety consideration if work must be done in the engine compartment while the engine is running. Electric fans can surprise you coming on without warning.)

The Flex-a-lite Variable Speed Control exceeded my expectations with improvements in every feature over the previous design!

peejay

Useless complexity. You want the fan to turn on at a given temperature, no matter how long the engine has been running or how long it's been shut off.

Say the engine is right at the temperature where the fan would kick on. You shut the engine off and restart it right away and let it idle in the parking lot, but your controller won't allow the fan to come on for five minutes. Overheated engine.

In practice, a fan is simply not necessary unless you're stopped. I could drive all day long and never have to turn the fan on. As soon as the speed got above 15mph you could WATCH the temp needle start dropping down to the thermostat temp. I would only ever turn the fan on under two conditions: Stopped for more than 10 minutes with the engine running, or for cooling the engine off (when shut off) between rounds when racing. A simple switch is all that is truly necessary.

A simple controller would involve a trim pot and a 741 reading the voltage on the EXISTING temp sender wire. The temp sender is a negative temp coefficient resistor, as temp goes up resistance goes down, so the 741 triggers the relay on when it sees the voltage drop below a certain point.

Jeff20B

iTrader: (13)

In order to get a fuel injection temp sender from a GSL-SE or later engine, you'd either need to swap in the complete waterpump unit or carefully cut some straight threads into your existing 12A waterpump housing. If you don't have access to a machine shop, I'd recommend swapping waterpumps.

Better yet, just keep it simple. I'm with peejay on this one. I've used clutch fans, e fans mechanically (thermocouple) switched and electrically switched either by the ignition or just a toggle switch in the center console or dashboard. As long as I'm moving forward, the temps stay at around 180° (or whatever my thermostat is rated for). The next thing I'm going to try is fan control from my Megasquirt

gsl-se addict

iTrader: (3)

Jeff: So the temp switch in the 12A pump has different threads than the SE or second gens use for their temperature sensor?