[brettus australia]

So last piece of the puzzle was where to mount the controller, without having to adjust any of the exising wiring or connectors.I'm only using one bolt to hold the controller in place, its quite adequate. One note, since the controller turns on at 96degC, the air blowing onto the cooling fins of the controller is quite hot, and therefore how much of a cooling effect it has is a bit dubious. I intend to later move the controller away from radiator with its own cooling fan, just a 12v from computer of correct size should suffice, in a cool area.
Here is the where I bolted the controller on the shroud:

I ground a bit of an angle onto the bolt hole so that the controller would sit in the airflow and also helped left hand fan wire to reach without tension.

shows bolt to connect controller below

shows controller in position

shows air intake back in position, controller sits nicely in that spot without problem.

 

[brettus australia]

So it all goes together nicely, last thing to do is stop heat to right hand motor from exhaust with additional heat protection, will do pics of that when done.
Also later will move controller to where it gets cool air and has it own fan, I dont think the mosfets will last long with 96decC or higher temp air blowing onto them.

 

[brettus australia]

just doing a bit of reading on these fan controllers and appears the aftermarket units do not last long, one post in this link says even with its own fan still failed.
outlander and evo controller discussion
I"m guessing its lack of capacitors across the output wires that go to fan, pwm type ebike controllers use quite large and multiple capacitors to protect the mosfets, they are also pwm based. I'm tempted to add some suitable caps ( probably 50v) across the motor output wires and see if they makes the unit last a longer time.

 

[brettus australia]

more info on controlling this controller
youtube vid
ecu signals
discussion forum how to control mitsu using various methods, starts with ardunio project but goes into other info
discussion arduino mitsu controller
The original oem controller seems to have been used for various projects running various dc motors by creative folk out there,
since can be driven with pwm signal alone to control speed and uses soft start feature to keep current inrush to a minimum.

 

[brettus australia]

Additional heat shielding for right motor near exhaust. I had a heat mat made from silicon fibres if I remember correctly it will suffice to stop heat transfer to motor from exhuast.
Since the mat is made from silicone fibres it needs to be covered as it will fall apart over time from vibration etc. First I tried to cover it with silicone, not successful, so then I wrapped it in aluminium foil, and siliconed that to the end of the right side motor.
I made it a bit big will make a smaller one at later date.

First attempt just with silicone not good wont last long will fall to pieces.

Below next attempt covered in foil, siliconed to motor, a bit large can make smaller one later

 

[brettus australia]

I did a post here about aircon not working with new controller but seems it only works once you turn on the interior blower fan,
I left battery disconnected overnight, thought it might clear any fault codes. So aircon is fine with new controller, fans come on full speed when aircon button is engaged.

 

[brettus australia]

Regarding old controller, I tested it, the fans come on full speed as soon as car is started,
and just stay on full speed at any temp. So I assume the unit is faulty, it is quite a good idea though that the default mode for damaged controller seems to be full speed.
I wonder how that is achieved?
I guess I can tear down this controller at some stage, its quite a job, will put it on the list.

 

[brettus australia]

so it turns out its not that hard to get the original controller units apart, they could be taken apart and repaired without completely ruining the case etc.
There are tiny welds that hold the outside connectors to the circuit board, the circuit board side are very thin nickel strip or similar, easily taken off the connector thicker nickel coated tabs. take off the capacitors and inductor coil easily done.
One screw to take out ( it connects I think negative input wire to the backingplate as ground) and the whole bottom heatskink can be pryed out, the silicone holding it in place is very soft elastic material.
PIc below shows polarity of caps

There are two tiny screws hold circuit board to heat sink, interestingly the whole board has a metal back plate which contacts the heatsink via thin smear of silicone or some heat transfer material. So the mosfets are cooled thru the backingplate of the circuit board itself, rather interesting design.
Pic below shows circuit board before removal, heat paste or whatever the material is requires a bit of prying at the board to get off, but comes off in one piece.

Circuit board main components:
circuit board no.: 1C231
mosfets 2x : F1010Ns 55v 85amp 11mohmn
schottkey diode ( or similar) : 926 s2 specs: 200v 5amp ( cont) 70amp( max)
main ic: c5202 920 first line, second line 0452C3001

Below this is rear of circuit board appears to be aluminium backing plate is integral part of the circuit board.

 

[brettus australia]

so I've done a little research on pwm controllers for dc motors, I had the idea of puting some extra capacitors across the motors wires to protect the fets. After reading up a bit on dc motor control, I dont think that is a good idea, ok for brushless motors but these are dc motors and I dont understand enough about the controllers.
I have identified the small 50v 100uf does go across the motor wires, the larger caps ( 50v 1000uf) might be matched to the inductor so not going to mess with something I dont understand.
The options to extend controller life might be
1. to have its own fan and be in a cool airstream,
rather than in hot radiator air.
2. Another option might to change the mosfets/schottkey diode in the cheap chinese controllers to a higher voltage rating, to match the original controller ratings . Thats a fair bit of work, so will just use cheap chinese controller as is with fingers crossed for time being.

If anyone out there has any suggestions to improve controller lifespan please chime in.

 

[brettus australia]

I put up a youtube video just showing how all the bits of the controller go together,
this is after caps/inductor removed and nickel tab spot welds removed.
radiator fan controller teardown

 

[brettus australia]

tested mosfets, mosfets working fine, turning on one mosfet turns on the other one also, rather interesting. Test with multimeter in diode continuity mode, the fets turn on/off no problemo.
So next culprit might be the schottkey diode, data sheet says forward voltage drop of 0.95v
but I'm not sure how to test just yet.
here is datasheet
ks 926 s2 diode

 

[brettus australia]

with multimeter in diode mode I get voltage drop of 0.395v, from the spec sheet the graph showing forward characteristics graph, for current less than 100mA ( from multimeter in test mode) that seems ok, so looks like the diode is ok too.
dont think I can go much further than that, there might be some small component on the board damaged or the ic .
Perhaps if the ic detects certain abnormal conditions it goes into mosfets on all the time mode to keep the fan running.....I have no idea.

 

[brettus australia]

Did a small experiment today. Since the fans turn when aircon is on, I decided to see how hot the chinese clone controller gets when fans are on, the car was slightly warmed up and a cool day today.
The fans came on slow speed contoller is warm to the touch on heatsink, after some time the fans went full speed, I can feel the heat transferred to my fingers almost immediately, it gets hot to the touch, I can keep my hand on there but its slightly uncomfortable on the heatsink.
The fans would cycle between slow speed for a time then go to full speed.
I can conclude the controller does not get all that hot ( in terms of damaging mosfets etc),
I'm guessing maybe 50degC or so. So it should be enough to use small fan on it .
If its in the hot air of the radiator you can add that temperature to the heat being created by the controller, seems to me better not in the hot air flow.

Also I note there are some micro cracks in the schottky diode of the mk1 controller, I will source some schottky diodes and and see if that solves the problem although the forward voltage drop seemed ok.

 

[brettus australia]

In my continuing irrational search for understanding this fan controller, a couple of things.
1. appears the small cap used to smooth out operation of the fan ( also found on tiny dc brushed motors)
2. the schottkey diodes role is related to the absorption of the back emf voltage spikes, a 200v diode is used, probably giving a very large safety margin
3.this is a bit of a guess:the inductor and two large caps involved also with voltage spike absorption?? not sure on that one
4. ecu signal previous linked shows schematic for the controller, internally it shows there is current sensing circuit. If overcurrent or other condition is detected what does the chip do?

 

[brettus australia]

came across an excellent youtube video on this controller:
controller
the guy goes into great detail on how to use it via cheap pwm controller which gives signal to the unit.
He also shows how to turn on/off the failsafe mode, when the controller goes into full speed mode..........now that is interesting. It is as simple as ground the pwm signal wire to go into full speed, and ground again to go back to normal operation ( see video link above at the 10min30sec mark)
He gives some amp readings with his fan setup, 24amp max dual fan, the controller has soft start feature so no inrush current at start up ( maybe inductor involved with that?)
He runs it at 500khz but can go much much lower, 24% duty cycle is fan start 100% is full speed.
**** excellent info

 

[brettus australia]

Since viewing this youtube video controller it seems possible that the controller might be able to be brought out of failsafe mode ( full speed all the time), simply by earthing the controller.
So it is worthwhile to rebuild the oem controller and try it, since the components appear to be ok........its worth a shot.
So i'll detail the process of puting the controller back together, it involves quite a bit of soldering tabbing wire, some skills in soldering required to do this, took me about 2 hours of work to re-connect the tabbing wires, some I had broken partially and one had come off the board, shown by red arrow in pic below.

Here is the reworked tabbing wires, looks a bit rough but I expect it will handle the amp draw if controller is useable. These tabbing wires are spot welded in factory I will have to make do with soldering.
I use phosphoric acid on all metals before soldering ( makes soldering nickel strip extremely simple and reliable), phosphoric acid can be bought cheaply at car suppliers as rust converter liquid.........my little discovery on soldering difficult bits.

Pic below shows base heatsink plate with circuit board soldered back into place onto bus bar section of controller

Pic below shows whole unit soldered back together, just have to put the caps and inductor back in place, will solder those also, polarity important on the caps of course.

If I hadn't used phosphoric acid as etch/flux on all the surfaces, I doubt it would be possible to solder all these bits back together in a simple reliable manner, thats my tip.

 

[brettus australia]

Regarding phosphoric acid with soldering, here in oz you can buy the rust coverter shown that is basically phosphoric acid, its price went up quite a bit recently so now I buy phosphoric acid 1 litre off ebay, which is cheapest way to get it, but its a little bit stronger than used in the rust converter so have to dilute it a little ( still quite suitable at stronger concentrations though). Basically almost anything I solder I put a little drop of this acid on before soldering and the joints come out A1.
Caution though, some car rust converters have another chemical ( primer) to make paint stick, dont use that one, I forget what lable they use somethink like "converter and prime"

Pic below shows the 'supercheap auto" stores rust converter that is suitable to use for soldering onto nickel plate, copper etc

Puting the caps and inductor back in place, pic shows drops of phosphoric acid on the solder points.

 

[brettus australia]

So the controller now all back together, just needs a bit of silicone to stop vibration of the caps and inductor..hold them in place as it was originally.
One note before puting the base plate back some silicone was smeared on the baseplate to stop water ingressing, as per original manufacture.
Some pics of resoldered caps/inductor, only took about 1/2 hr or less to put them back in place.
The caps wires went back into original position without issue same with inductor.

 

[brettus australia]

I've ordered a pwm frequency generator ( from aliexpress) same as the one shown below
which I'll have to wait to arrive before I can test if this controller can be unbricked from failsafe ( fans full speed) mode. I dont want to try it "in car" will post results when done.
These cheap frequency generators will give the correct signal to run the controller at different speeds.