Is there a Quark 125B thermal problem?
 

Hi,

I am hearing that people at having over heating problems with the Quark 125B?!
Are the transistors not making good contact with the aluminum case or something? I WAS planning to lap the bottom of the Quark and use Arctic Silver paste and mount it to the upper aluminum chassis for very cool running.

I hope this isn't true since i just got my 125B yesterday, and a 540C 7XL.

ANY and ALL issues, comments on the subject are appreciated.

Zeropointbug

The Quark does have heat issues. But with proper cooling you should be fine. If you look on the store, there is a heatsink that is sold for this application.

I wonder if lapping/sanding the bottom of the Quark with 600 fine sand paper and using Arctic Silver and pressing it to a thick aluminum upper chassis brace that would take all heat away.

I would get the heat sink and not sand the bottom of the Quark. Then use the arctic silver to attatch the heatsink.:027:
you could however drill holes in the heat sink as well. I think this is what Mike did to his.

You don't have to lap the bottom, it would just increase the heat dissipation (not by much though). That Arctic Silver is some THICK stuff though, i've done quite a few CPU heat sinks and just a membrane of the stuff is enough... well i shouldn't say that, THE THINNER THE BETTER, PERIOD.

The heat problem with the Quarks is two-fold really.

1: The case doesn't have enough thermal mass or fins to effectively pull the heat away from the FETs and dissipate it. This is where an added heatsink comes in. Even though the ESC doesn't have a beefy enough heatsink out of the box, at least Quark provided a nice spot to attach one!

2: The construction is a bit wacky, but for a reason. There is an Aluminum slab between the FETs and the case. This slab is held to the case via some type of soft rubbery thermal pad. The same material is use between the FETs and the slab. So there are three layers of material between the FETs and the casing; FETs -> thermal pad -> slab -> thermal pad -> case. So thermal transfer isn't the best right out of the box. The slab is really just a spacer so the caps on the end will sit right.

I'm sure the ESC would run OK like this since that is how it was designed - but after some use and dirt working its way into the case, the adhesive on the thermal pad becomes somewhat unstuck. Of course this drastically affects heat transfer.

What I did was pull the ESC apart (be careful of the SM cap by the button!), and remove the ESC circuit from the case and remove the rubber stuff on both sides of the slab. Because the rubber stuff is fairly thick (about 1/2mm), a new thicker slab needs to be made. The existing one is about 2mm thick so, a 3mm (1/8") thick piece of aluminum works great. Once cut to the right size and polished, and apply thermal epoxy to secure the FETs to the slab, and then epoxy the ESC/slab to the casing. Just be careful not to get the Arctic Silver stuff on the FET leads, unless you use the non conductive version.

Once the epoxy cures, you'll notice a huge difference in the thermal properties of the ESC. It will heat up faster and cool off faster. It will also feel hotter to the touch when running. These are all good things because it means the heat is not staying IN the ESC. Add a heatsink to get rid of that heat and you are golden.

Of course, this almost definitely VOIDS THE WARRANTY, so be advised.

You wouldn
t happen to have pics of this process would you? LOL

Sorry, no pics. It's pretty easy to do really.

Care to donate your Quark for picture-taking purposes? ;)

I forgot to mention that once you do this, it's not coming apart without something breaking. You might be able to seperate the slab/ESC from the case, but that's about it. I know of no solvent that will dissolve thermal epoxy without damaging anything else in the process.

I've been contemplating on donating it period! LOL
I think, this would be the reason they use pads, so that they can take them apart to work on. I thought about this a long time on how to do it better. Mine really does not get that hot though right now. Mainly for me, it's the start and stop thing that I'm working on getting resolved right now.
But basically, if I take it apart, I will need two slabs of 1/8th" of amluminum to replace the pads right? I already have thermal epoxy that is Arctic silver. Not sure if it's non conductive though, will this matter?

Here is a thread with more on the subject a long with some pictures http://www.rc-monster.com/forum/showthread.php?t=3861. I have done something similar to BrianG with my Quark. Since I have modified my ESC I have been really happy with it's performance. It has not thermaled since its been modified. I don't even use a fan on my esc, 1/8 buggy for 25 minute runs.

BrianG used a 3mm slab of aluminum between the FETs and the case and then it has the perfect spacing. That way is easier then the way I did mine. It really is easy to do. The hardest thing to do is open the case!

I just ordered another Quark for a CRT project, I'm sure I will modify it as well.

Hmmm, maybe the aluminum slab is for durability reasons maybe? Instead of having the FET's right up at the case...

I also checked the FET, from what i can see the FET's are Infineon made, and are rated at 30V, and 100A capability each... thats the page i found anyways.

I wonder when ESC makers will utilize heat pipes to dissipate the heat, VERY effective, and makes for a lot of options as far as setup.

Do you think i will be okay with running 5s2p A123 cells with a 7.5 lb 1/8 emaxx buggy conversion, as far as thermals go?

Now wait, i found another page that says 50A. And 2.2mOhm, and it looks like them too.

They are called "OptiMOS 2 power transistor"

They drain at 50A even at 100 degrees celcius, and 200A pulse at 25 degrees

Power dissipation is rated at 104watts, wow.

Neweuser: Well, you can donate it me if you'd like. :) If you do what I did, you will only need one 3mm thick slab. Regular AS adhesive has some capacitive properties and might cause problems if it drips onto the legs of the FETs (especially the gate lead). AS has another type that is non-conductive and non-capacitive. However, I was careful and used the normal stuff and haven't had any problems. I'm sure the use of the padding was somewhat determined by ease of working on it. I know mine is useless for warranty work now, but I personally think it was worth it for the thermal performance compared to what it was before the mod.

zeropointbug: From what I can tell, the slab is more of a spacer. The electrolytic caps on the end of the ESC are a little higher than the tops of the FETs, so the slab takes up some of that space. It probably also acts like a heatspreader to some degree as well.

The datasheet for the FETs can be found here. In this post, I made some observations about these FETs and why they may not like 6s. make sure to look at the derating charts...

Irun a 80b quark with pretty good sucess. I mounted it flat on the aluminum chassis.

Coolhandcountry What motor and how many cells are you running off the 80B?

I don't suppose you've tried 6s with it? I imagine it uses the same FETs as its big brother, just fewer of them...

Hey BrianG, what if you were to use a copper spacer in the esc instead of aluminum? Also, you could even cut out the bottom of the case and stick a nice heatsink right out the case and directly on the FETs. It would be a little risky though.

A copper plate would conduct the heat better/faster, but really, Al works well enough once it is installed with less thermal resistance. The copper slab or cutting the case would work [b]better[/i], but I have had great results just doing what I did alone.

Well, you know what, i think i just might do this. Where do you start then disassembly then? Do you have a unsolder the motor tabs then?
You can just give a quick brief, i can take care of the rest...

BTW, don't you love how smooth the quark is?! It's so juicy.

You can pop off the end where the power wires go in. To take the other end off, you need to desolder the motor wires. You can try to slide the top plastic plate off, but there is a surface mount cap by the button that may get ripped off (happened to me). You can also simply pry on one side until the plate comes out of the groove. Either way works.

Oh, and a final warning; this will most definitely VOID THE WARRANTY! Do at your own risk...

I am currently running a 1512 2.5d neu on it. It is currently run with 4s lipo.
Yes I have trid 6s limn on it. It had a bad start up. After I got it going it was
ok. It was like had to warm esc up or wear batts down a little. When I say
start up. I mean like first hook batteris up and try to go. Not stop and go.
I tried 6s with a 1930 10t and it poof fried esc and motor. I have ran a 9xl on
it as well. I tried a xl 1200 basic. I have tried a 12xl as well. All the motors had
same issue with 6s. I went back to 4s and have had no issues what so ever.
I do get about 45 to 60 mins of run time on 8000 mah maxxamps pack. :D

Hey, that is pretty good run times CHC. I'm wondering what run times I'll be getting with my Neu 1515 1/y?

How i want a Neu motor... next year i'll get one, hopefully i'll have ran my 7XL before then. It's pretty snowy here now so, i'll see if i can seal up all the electronics and put my ProLine paddles on. ;)

Ya, that is very good runtime.

CHC's motor is only 2000kv for about an L size motor, which is not a very "hot" motor. The 1515 1y is a larger can and higher kv (2200), so I'd say between 25 and 35 minutes depending on driving style, weight, etc.

Can you guys give an estimate what my runtime will be with the C-7XL, with the Quark125B and A123 pack of 5s2p of 16.5volts and 4.6Ah. It's a sort of buggy-truggy ;) ... it's high of the ground, but has 1/8 buggy tires (Badlands). The weight fully loaded will be around 7.5lbs.
Oh, and thats geared to go about 50mph

Any guesses? I am thinking around 15 -20max minutes?

The 1512 is definitly a bigger motor than the L can motrs. Much more powerfull also.

So, what do mean by that jhautz?

Just wanted to point out that the 1512 is a larger motor than the L can Feigaos is all.

Bigger diameter and it puts out more power than a Feiago L ever would.

Yeah, the Neu is larger in diameter and is a different class of motor altogether really, but I was comparing rough KV and can length values...

BrianG, so i popped off the power input end of the Quark and looked inside, pretty neat looking for sure. So did you say you would need a 3mm slab of Alum./Copper if I replace the two thermal pads/slab? What is actually holding the whole circuit to the case? Is it purely the thermal pads there? If i were to do this, i would be persuaded to completely seal the ESC right up to make it basically waterproof, and keep dirt out.

If i were to just attach the Quark to an upper aluminum chassis brace that would have alot of thermal mass and heat dissipation capabilities, would i even have to bother with making the thermal adhesive mod? Because there would still be a large temperature differential between the transistor surface and the outside of the case. I like to make things the best i possibly can, and quality is my name. ;)

Would you have any suggestions for using to seal all the holes in the ESC that is not conductive and that is thick applying, such as Silicone Caulking? I think this would work too.

Cheers

Yep. The existing slab is ~2mm thick with two pieces of thermal pad (~.5mm each) for a total of 3mm. If you remove the pads, you remove ~1mm of thickness and then the caps prevent the FETs from sitting flush on the case. And yes, the thermal pads are what holds the whole circuit to the case.

I suppose you could waterproof it while you're there anyway. You'll have to use some material that won't weaken or get soft when substantial heat is applied, that won't get brittle after time, and can endure the vibrations and jarring. Maybe epoxy may be a better choice?

You can do whatever mod that makes you feel good. :) I just had good luck with what I did, but I'm sure there are other ways to get the same (or better) results.

Good luck!

Shoe Goo ???

I think Silicone would be perfect then, once it cures it's then almost the consistency of the silicone wire insulation (prob more flexible).

Also, are you sure you have to unsolder the motor wires? Can you not slide the top cover left off of it? Where exactly is the cap. near the esc button?

jhautz: I tried Shoo-Goo on something else and it tends to get brittle and seperate from the thing it's trying to seal. I would think something flexible, yet heat/water/motion resistant would be better IMO as long as it bonds well.

I unsoldered the wire simply because it looked easier. You might be able to work the end off without unsoldering, I don't know. I guess you'll just have to try it. :)

The caps are on the power wire end (since that is where they are used).

BrianG, i tried taking the cover off without unsoldering the wires, i couldn't get it to come off. So i unsoldered the wires, and slid it off and noticed that the only thing stopping you from doing it the other way is the little see-threw plastic window for the LED's, it hits a little IC beside it.

Anyways, i go it all apart, except for taking it off the case. I notice that there is two alum. slabs one on both side of the bottom circuit board, and it looks like they are the same FET's ???!!! What!? Do you know if this is true? Or are they for something else? CHeck the pics, if they are the same FET's then maybe all they need is some heat spreading? And the thermal pad is just to attach to the case? It also doesn't really look like the pads are .5mm, they look thinner than that, maybe .3mm? I don't know... I don't want to take it apart yet, i don't have Thermal Adhesive at the moment, i'll pick up some Arctic Silver stuff when i can.

So is there two layers of FET's on the two sides of the power board?

You should really use the Arctic Alumina from Arctic Silver to bond the aluminum slab to the FETs. "Arctic Alumina Adhesive is a pure electrical
insulator, neither electrically conductive nor capacitive." here is a link http://www.arcticsilver.com/arctic_a...l_adhesive.htm . When I did mine I could not find it locally anywhere so I had to order it online. PC shops online are the best place to get this stuff. It is good stuff, but it's a perment bond!

I only bonded the outside FETs to the slab and case and did nothing on the aluminum slab that is sandwiched between the boards.

Your pretty brave doing this on a brand new controller! :027: but it does make a difference especially for bigger vehicles. It seems to cool quicker and overall more efficiently.

Hey, just to add, it appears once i took a closer look, that the slab attached to the case is only touching on the edges, it's not even touching in the middle...

Yes i was planning on using Alumina.

Do you think this mod is necessary for a 1/8 emaxx buggy? It will weight in at about 7.5 lbs. What do you think?

hello zerpointbug,

may i ask you, are you try setup your esc the Drag Brake function yet?
it's at menu Table 3.2-3 and Table 3.3-2 , would you feel free to test it
and try power off then power on, the function will off , if you set ON before.

i have 5 esc 2 new(3color wire), 3 old(white color wire), 2new esc can't store memory (just Drag Brake) , 3 old esc is normal.

i want compare your esc with me.

Thank you..

How did you get 5 of them! WOW! Do you live in Thailand by any chance? LOL

zeropointbug:
The cover plate does slide off if you pop that little clear piece, but it's still kinda hard at first. So, I just popped off one side and it came right out. It's plastic so it bends a little.

The slab in mine was touching the middle as well. The pad covered the entire slab on both sides.

The inner slab is actually for another set of FETs. There it acts like a heat spreader. Ideally, you would find a way to attach that slab to the case as well, but it would be a little difficult. Smertzog (or something like that) installed huge heatsinks on his, but doesn't use the case anymore.

As far as if it is necessary for your emaxx: Improving its thermal characteristics is good for ANY vehicle, but makes more of a difference with heavier ones. Cooler devices means better reliability and longevity.

andywpj: Wow! You must really like the Quark controller!