BuiltZ28

After years of running a rocker switch I am in the market for a fan control for my non ecm equipped car.

I see now derale amongst other companies are offering variable speed control boxes. Has anyone used one? Does anyone have any input on them?

They are about 100 dollars more than a fixed control, pretty reasonable.

zed-028

I've used these on a number of cars. Surely America must have some sort of equivalent, maybe an Aussie ebay seller will post one

http://daviescraig.com.au/product/di...h-12v-24v-0444

Drew

iTrader: (58)

I'm kinda partial to the stock style thermostatic switch controlling a relay. It doesn't get much simpler. No need for a manual switch, but you can always rig one to trip the relay manually. I'm sure there are reasons for multispeed controllers, but it seams like needless complication.

zed-028

thats basically what that linked product is - they work really well

BuiltZ28

Its pretty far from complicated. I agree not really necessary just kind of cool

scooter

iTrader: (11)

I think the newer GM vehicles use PWM for the fans, should help lengthen the life of the fan motor since it can run at a lower duty cycle when the load is not needed, plus it can ramp in as the cooling system is operating, rather than just on/off

OrangeBird

iTrader: (1)

I believe anything doing PWM will be a three phase brushless motor being driven very much in the same way that a model airplane electric motor setup is done , just without the LIPO battery and having the ECM signal the PWM controller instead of being able to manually control it by the stick on an RC transmitter . If it's a standard brushed DC motor there are really only two ways to reduce it's speed , kill off the "extra" power through either a resistor or a transistor , both methods producing considerable heat . I see the device mentioned earlier has two relays , my guess would be that those two relays control how much or little resistance is added into the circuit to slow the fan down , if it were transistors doing the power reduction you'd surely see heat sink fins protruding somewhere from the box . My 03 Lincoln variably controls the fan , I'll have to look later if it's a regular DC brushed motor or not .

RBob

iTrader: (1)

PWM works great on standard brushed DC motors. I've been doing it for a long time.

RBob.

OrangeBird

iTrader: (1)

The newer setups though are all brushless though , so there must be an advantage to it .

RBob

iTrader: (1)

Yep, no brushes or commutator to wear out or squeal. The brushless motors are more efficient too. Downside is that they take a bit of electronics to run them. But over the life of the motor, as long as the electronics holds up, more then pays for those electronics due to efficiency (less power used, better CAFE ratings).

But the fact remains that PWM works very well for motors using brushes. As for brushless motors, the input speed signal can be of several or more different types. The electronics needs to convert it into a set of signals to drive the brushless motor.

RBob.

Vader

SCR. It doesn't get much easier, unless it's a mechanical fan.

https://www.banggood.com/12-50V-30A-...p-1000401.html

Instead of the pot, switch stepped resistances in via transistor or relay/decade. And it's only ten bucks.

Yrs, RBob, that's technically a PWM scheme, holding off firing lead edge.

Pro

I use the flex a lite variable speed controller. Its been working for 18 years in the truck and 2 years in the camaro. It mounts perfectly right in front of the battery, behind the headlight, without drilling. And I picked up new wiring harnesses to run from it to the fans, and left the old ones zip tied to them. That way in case the controller dies, I can just unplug the new connectors going to the controller and plug back in the stock control.

RBob

iTrader: (1)

Be careful clicking on that link, there is a script that runs that goes back to a .ru site. I have it blocked so don't know of it's purpose.

It is rare to use an SCR to control DC power. Once an SCR starts to conduct it needs to have the current stopped so that the SCR can stop conducting. It gets messy as this isn't easy, an inductor injecting a reverse voltage can do it. But why bother with expensive and large reverse kick circuity when a simple MOSFET works so much better. Use a modern 50-cent uProc to handle the input to output control of the MOSFET, done.

GM ECMs have multiple PWM outputs. Great for stuff such as progressive N2O or alcohol injection. The first place I used a PWM'd brushed motor was electric RC planes. Then a train setup for the kids. One thing about proper PWM control of a motor is that the torque holds.

If you vary the voltage all kinds of issues pop up. PWM doesn't vary the voltage, just the time the full voltage is applied to the motor.

I am surprised that you posted that (your posts are typically very accurate). One item that is surprising about that controller is the PWM frequency: 21 kHz? The motor would have to be tiny, as skin affect will take it's toll.

RBob.

Pro

I looked at the russian javascript and it looks harmless, just annoying. Its a forward to the european version of facebook apparently