Inside the Quark 125, pics.
 

Here is what the insides look like.The plastic end of the ESC keeps popping open (battery wire side). So I opened it all the way. I was thermaling today even with heatsinks and fans. I think the plastic end holds it so the fets are pushing on the thermal pad. I'm thinking just bond a heatsink directly to the fets. Then shrink wrap it, but I'm a novice when it comes to electronics. Anyone have any ideas for keeping it even cooler.

That is interesting. I took mine apart but the FETs were stuck pretty good to the case and I didn't want to break any, so I never got it apart that much. Looks to be well constructed. Is that an Aluminum heat spreader between the PCBs? From the looks of it, there are 12 FET IC's per phase (top and bottom of the PCB), not too bad. Can you read the part number on one of the FETs? I'd like to look up their datasheet.

Of course, anything you do to mount it differently will probably void the warranty, but I'm sure you knew that. You could mount the assembly in a better heatsink like this (from here) inside the channel, and then fabricate some kind of enclosure to cover the other parts of the ESC. NOTE: Do NOT use thermal epoxy like normal Arctic Silver. The paste will squeeze out when you press the FETs on the heatsink and the silver particles may contact the FET leads and/or PCB traces and cause problems. Even if you don't get a direct short circuit, the particles can introduce capacitance. Make sure whatever thermal bonding agent you use is electrically insulative, yet thermally conductive. You can use this instead - same company, different blend.

Also, when I removed the top plate (where the LEDs and button are), I accidentally ripped off a surface mount capacitor. I was able to resolder it, but it was a pain due to the size. You might want to check to make sure you didn't do the same. I can tell if you did or not if you could post a picture of the top board if you want.

Thanks for all the good information. Yes, there is a Aluminum heat spreader between the PCBs.

As far as the FET part numbers go, unfortunately, I just put it back together, but was able to blow up my picture and Here they are: 22N03S GAC529.
For some reason the FETs were no longer stuck to the thermal heat pad or tape or whatever it is. There is some movement to the boards inside the case, maybe due to being mounted on it's side. Can't be very good for heat transfer. I may have to do something about it.

I don't think I ripped the capacitor you were talking about. I wish I would have checked more carefully. I was planning on running it again tomorrow so, I put it back together. I will probably open it up again. When I do I will get it a picture of the other side.

It's a little scary that the Arctic Alumina Adhesive is a permanent bond.

Thanks for the part number. For those interested, here is the datasheet for them. Some interesting points:

• Rdson is pretty low at ~0.002 ohms. Paralleling 12 of these brings the total value to ~0.00016 ohms.
  
• 50A rating
  
• 30v rating. Maybe this is why some of these don't work well at 6s lipos? 6s under a full charge would be 25.2v, which is quite close to the max rating of 30v. However, a look at the "3 Safe Operation Area" graph, you can see that it is good for 50A up to 20v. Past 20v, the safe current goes down. Hmm, interesting.
  
• Dissipation up to ~105W. Of course this assumes an adequate heatsink. The derating graph ("1 Power Dissipation") shows that it is 105W up to 25C. Above 25C, the power is derated about 0.9W/degreeC.

Was the thermal pad sticky at all? There has to be something to hold the FETs against the heatsink. If you don't want to use a thermal epoxy of some kind, you could get some thermal tape instead. It won't work quite as well, but I understand your point about the epoxy being permanent.

Edited for stupid spelling error

To my recollection many other brushless controllers that can handle 18 cells have FETs with a 50v rating. You did some good work, Brian, in figuring out a very possible cause of the Quark's disliking of 6s.

Thanks. Although without CartWheels taking it apart, we might have never known.

At first glance, 30v looks fine, if a bit close to a 6s charge. We might also have to think about the inductive kickback (back EMF) since the signals the ESC sends to the motor are square wave AC. Back EMF under a collasping magnetic field can be extremely high depending on the inductance of the motor coils. Of course, the reverse diode in each FET is supposed to help curtail this, but if it has similar limitations, it might no be doing its job. Maybe this also explains why some people can run 6s and some can't - the type and wind of the motor. Or it could be some FET batches have a higher tolerance than others.

The periodic problems with the quark simply can't be related to the current capability. Even grossly underrating the current of each FET for temperature, it still has plenty of current capacility. If each FET only supplied 10A, that would be three phases of 120A each (assuming 12 are paralleled per phase)!

Even with this "problem" the Quark is still a VERY nice ESC and wouldn't hesitate to buy it again. The construction as seen here is very high quality. They even added a heat spreader between the PCB instead of relying on pure stacking. So, we know we should only run 5s tops and add cooling for best results.

My thermal pad was not sticky at all, but that may be due to me running in dirt while the boards were loose and a plastic end was opened up. The thermal pad just feels like a soft pad. I kind of wonder if it is part of the overheating problem in general. I know for me it is part of the problem because the FETs aren't making good contact with the thermal pad and the heatsink.

I ran it today. It ran good, but it did thermal on me after about 10 minutes. I tried to tape the boards so they wouldn't move around, but it just wasn't enough to hold the FETs against the heatsink. I have to take it apart again and I think I will remove the thermal pad and use some of the recommended epoxy to fix it once and for all.

How difficult is it to change the FET's? Not sure if its possible, but maybe a higher voltage FET?

Ugg! While I'm sure possible, it would take a very long time to remove all 36 FETs and solder in new ones. You'd have to separate the PCBs for one thing, and you'd have to have a quite small tipped iron for this job. Plus, by the time you buy all those devices, the price and labor would make it preferable to simply buy a new one. Not to mention that there might be other devices with similar working voltages. You'd end up building a whole new ESC!

Well if you did, that would make it one damn good controller.

i know selvester was thinking of doing just that, he was going to take apart his 9920 and look at it and order far better components and and on top of it mill his very big alunimum heat sink. But because hes busy and lack of time, re-considered it.

he did tell me that when he comes back that hes going to add avery large heat sink to his 9920.

I'll be curious to see how it all turns out. Is he looking for more current capability, or just better cooling? Any idea which FET he plans on using?

The only perfectly built ESC I've seen is the CC Phoenix HV-110. Each layer has an Al slab connecting to the heatsink and the main heatsink looks quite beefy. It's probably a PITA to assemble those since you can't just slap the PCBs together and then slap a heatsink on the top layer of FETs. The Quark is probably the next best as far as construction goes.

I don't think the voltage limit of the mosfets is the problem with supporting 6S in the ESC. Mosfets will keep operating just fine at higher voltages until they fail - and when they do fail you'll know cause you'll smell that lovely electronics smell. Without having one of the controllers to look at I believe the problem with higher voltages is simply a function of how fets work, in general you need/want a higher voltage on the gate(the on/off pin if you will). To get this higher voltage pretty much all ESCs have a voltage charge pump(booster) So even though you may have a 6 cell nimh pack connected the ESC is turning the fets on and off with 12 or more volts. I am guessing the charge pump in the Quarks isn't high enough to keep the gate voltage higher then the input voltage, and as a result the fets will not turn on properly.
The ESC above appears to have 36 fets (6 per phase) which is a very solid design. Even the Schulze U-Force which is a very good controller only has 18 fets in it(3 per phase)
Also the fets they are using are quite good - rated at 28 amps in real world conditions.

And this story about FET's and high voltage based on?
And do not blame fet's control if you not sure how it works...

Artur

What about the caps? What voltage are they rated at?

Based on education and several years experience working with, repairing and designing speed controls that use mosfets. And anyone thats knows basic mosfet operation would also know...

I'm looking at this thing trying to think of how to get more heat out of it. Adding additional mass to the bottom seems to make a huge differeance in disapating the heat. But thats only taking heat off of the bottom layer of fets. I'm thinking that opening this thing up and adding somethiing to the sides of the heat spreader to help pull the heat out of the middle of this thing could be the ultimate way to heatsink it.

Do the sides of the heats spreader contact the aluminum sides of the case?

This is really interesting to see how its set up inside. I have been wanting to tear mine open, but didnt want to void my warranty.

Cartwheels, If you open it again can you get some pictures of the top board also? Anyone know what part of this thing is the BEC?

Well, then any good (Quark is good) pump-charge based (not fixed 12V) fet driver has a feedback, which helps to set the voltage at level which guaranties FET's turning on and FET's safety (not to exceed GS voltage) and as well fast transition and...
Based on this your previous guess is wrong!

And any comments on Leroy's question as a professional?

Artur

I have my Quark opened up again. I'm going to need to secure the Fets to the heatsink since the boards are just sloshing around inside the case. Here is a picture of the inside of the heatsink.

It has a piece of Aluminum secured with what looks like a heat pad. So it goes heatsink, heat pad, aluminum and then heat pad stuck to the Fet's. Maybe this is part of the cooling problem. If the Artic Alumina is better than a heat pad, I would probably remove the 2nd heat pad too. Are heat pads very efficent?

Here is also a view of the top of the boards. The heat spreader does not touch the heat sink.

depending. The thinner the layer, the better. as long as the contact area is optimal.

I would use thermal paste to hook the aluminum to the case and use a thermal pad to connect the fetts to the aluminum spacer.

Now you have got it open, can you please check the voltage on the caps?

On the caps unfortunatly, I can't find any markings other than: TDA . There is about 1/3 of the cap I can't see though. Is there another way to tell the voltage.

Remarkable..

sure you can keep uping the voltage untill it blows :027: j/k that wouldnt be good to do. the voltage is probably on the 1/3 you can't see.

You could ask Mike what the voltage is, he MIGHT know. Or even, send Qaurk an email and ask....they would definately know.

Update: While I had my Quark apart I decided to go ahead and remove aluminum spacer between the heatsink and the fets. It was held on with a thermal pad. It was only half stuck on. You could tell that dust had gotten to the thermal pad. Half the pad was covered with dust and the other half was stuck on well.

My plan was to put it back together and substitute thermal epoxy for the heat pads. The epoxy is much thinner so I had to carve out some space for the caps in the heatsink otherwise they would prevent the fets and the heatsinks from fitting flush. I also had to trim some of the plastic under where the phase wires come out for the same reason. I've got it all back together and have not run it yet, but I expect it to run at least a little cooler. I had 3 fans on it before and it was still thermaling.

In conclusion, I think the thermal pads can contribute to some of the thermal problems with the Quark. The sticky part of those pads just can't hold up to the rough, hot, dusty environment and will fail eventually. Not to mention the heat has to transfer through 2 of those pads to get to the real heatsink!

The real test will come when I run it again. It my be a week or two before I can run it again.

Very good. Let us Quark users know how it does. Thanks for all the info!

Have you tried it out yet?

Tomorrow, I'll be running it with no fans. I've got my fingers crossed.

Have you got a temp-gun?

I have a temp-gun. It's one of those small Dura Trax ones.

I did run the Quark today. My setup has changed from what it was. I'm now using a Neu 1515 1Y. Batteries are the same, 4s 7400mah lipo and gearing is 12/51. Before I was using a 540c 9L and I always had trouble with temps creeping up to 200*F and above towards the end of the run.

Look Mom No Fans!!!
Today went good with the Quark. It never thermaled on me even without fans. It does have a pretty good heatsink mounted on it with the front windshield completely cut out for air circulation. Temps stayed in the 125* range for a good portion of the run. It was pretty much all out non stop going for approx 20 min or more except for a couple of temp checks. Towards the end the temp did get up to about 147*, but it never thermaled. The motor was at 159* at the end. The outdoor temps were much cooler then a month ago when I started this thread. It was a nice 88* day.

One of the most notable things was the temps at the boards where the motor wires come out. In the past that area was generally 15-20* hotter than the heatsink. This time those temps were only 1-3* difference and they would even out within a minute or two. To me that was pretty significant. It tells me that the work I did may actually cool the internals better and more quickly.

Quark vs. Mamba
The Quark felt like it had a higher top speed. The Mamba felt like it need to go up a tooth. Punch seemed equal. Quark overall had a more powerful feel while the Mamba felt a littler smaller. Don't get me wrong though I love the Mamba, but for 1/8 if you can get the Quark not to thermal I think it is a little more suited.

In the end I think I may still have to run a fan on the ESC, but I'm going to push it and see what happens without a fan first.

Sounds like your work on the Quark paid off! If mine starts thermaling, I'll take it apart and do something like what you did since I'm sure the heatpads will have come unstuck as well.

I ran the buggy again sunday late in the day. Ran it as hard as I could for 25 minutes straight. Temps were great. At the end of the run the heatsink was 132* and the board where the motors wire come out were actually 5 degrees cooler than the heatsink. I've never seen that before. I'm really happy with it so far.

Here is a picture of the buggy. The Quark is mounted upside down and also I threw in a picture of the open ends of the Neu motor, which I later taped up.

Sounds like you may have got something there, I'm just wondering how much of the heat drop can be due to the neu motor. That and the ambient outside temperature make a big difference. I just noticed mine is loose and am going to do some changes. The shrink wrap on my caps looks like it got hot and came off, they read 35v 330uf . Im also wondering if the fact that only one bank of the fets is connected to a heatsink that sees airflow has anything to do with the overheating.

Hey, thats a hyper 7 i see there ? What size pinion/ spur are you running on that ? Do you have the spyder or normal center diff ? Plastic or metal spur ?

and last one, any fan on those heatsinks ?

Thanks !

Scy

There is an aluminum heatsink on the inside row of fets but, your right the outside bank is the only one that sees airflow. No doubt the motor does help but I can tell that now that the fets are better attached to the heatsink the internals cool much quicker.

When you say that you are going to make some changes are you going to do something like what I did or something else?

I'm using a 12/51 pinion/spur on the normal diff. Mike (RC Monster) made an adapter that fits the diff to the spur for me. The spur is plastic and holds up quite well. I don't have a fan on there but, I have the front windshield cut out completely which provides some air through the heatsink. I would put a fan on there too but I can't keep the fans from breaking so, unless I have to have one I will go without for awhile. I was really happy with the way it was running the other day.

@scy;

you can also hoop up the kyosho spurt to allmost any centerdiff, they are plastic, and don't require the adaptor. they come in 44 and 46t.

I would most likely need a whole new diff since I have a spyder diff and the spur gear doesnt fit at all.

:(

I bet Mike could make an adapter to fit your diff as well or maybe you could make your own. Here is a thread that has pictures of the adapter http://www.rc-monster.com/forum/showthread.php?t=1897 . I believe it would be similar to mine just more holes for mounting on the diff. I did mine before too many people knew about the Kyosho option for the spur.

What do you mean with spider diff? you have got the (what UE calls) 8 spider?

Quote: When you say that you are going to make some changes are you going to do something like what I did or something else?


I just started today and am waiting for some supplies to get here but this is roughly the heatsink setup I am planning on using. With as dirty as the inside of my controller was when I took it apart was, I think Im going to shoot for keeping the boards from shorting on anything as apposed to sealing the whole thing up with the original case. Ill use the original face plate with the button and window to cover the board but not the alluminum case.

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