Custom (very) Quark esc heatsink...
 

I don't know which one to use yet, the big one will sure keep it at a very low temp, you could prob run the La Mans 24 hour race!

Large one: 220 grams

Small one: 66 grams

Both will weight less once finished, as i have to remove some heat spreader, and lap them both.

Wow, that thing will work wonders. Definately keep us updated on the temps you get.

There, I ground down all the excess copper heat spreader around it, and the pad fits the Quark perfect both orientations. It now weights 140 grams.

All i have to do now is go and buy some 600 grit sand paper and lap the thing until it's perfectly flat.

I just finished lapping the heatsink. Dang it was hard work, i went too deep with the grinder beforehand, the sanding could not remove the marks.

I also got my shrink wrap in for my packs.

Awww man, that's not lapping! You should be able to see your reflection like it was a mirror when you're done! ;) That's one big heatsink! You gonna mount the front and rear suspension directly to it? ;)

LOL, i was planning on using it as a bulkhead!

I know, i know, not the best lap job i've done, but that's the best that 600 grit will get you! PLus, the grinder scares could not be removed.

The Quark sits very flat on it now, in fact, if I put a drop of water on it and put it on glass, it takes quite a bit of force to remove it. Which is a good sign of flatness, and smoothness. All I have to do now is get a copper pad (what was it 3mm?) for inside the Quark.


OH, and the 'La Mans" association called, and they said I'm qualified for the 24 enduro races! :005:

BrianG, what was the thickness of the copper plate 'mod' for the Quark, and was it you that did this? I seem to recall something around 3mm? Is this correct?

I think this thing would have a 200 amp continuous current capability now, LOL.

Yes, you will need a 3mm plate. Btw, I recently modded another Quark 125b without removing the motor wires. Once you have the top lid off and the front plastic off (power in side). You can use a small 3 inch long flat blade screwdriver. Slip it under the caps and gently pry between the aluminum spacer and the aluminum case. You will end up removing the insides and the rear plastic piece all at once. This way is much easier and cleaner without removing the motor wires. Let me know if this doesn't make sense.

some pics would offer great help Cart!

I did take some pics, but you really couldn't properlly tell what was going on. The best I can do as far as pics go is this old thread with pic's of the Quark. http://www.rc-monster.com/forum/show...t=inside+quark. There is a good picture of the case and the aluminum spacer on page 2 on the left.
Just make sure you pry between the case and the spacer and not on the PCB board. Otherwise it is actually a simple deal.

I see what you're saying. However, I personally would prefer to remove the motor wires so that I don't have to deal with the endcap when trying to reassemble. It's really not hard to desolder/resolder the motor wires - just gotta have enough heat to melt the solder quickly while overcoming the heatsink qualities of the wires/PCB traces. :)

Thanks Cartwheels, i removed it without the motor wires. Wow, that thermal pad is one sticky mother! Only 1/3 of the pad was actually touching the case, talk about useful/less.

I just ordered some Arctic Silver adhesive last night, so it should be here thursday or friday. Just imagine if i attached the PCB directly to the heatsink :018:

Also, i think heat will bleed through the PCB and trhought the bottom FET's and then the heatsink, as the traces and PCB are quite thermally conductive after all. The water cooled units only have tubes on the side of the PCB's, and they seem to work very well...

Here is a pic. Do you guys have that pink strip in each 'phase line'?

Quark should integrate the mod on future versions of the 125.....call it the 125C for copper!

I know you guys will razz me about that one! LOL!

Yah, that IS a pretty dumb idea.... :mad:1


LOL, just messing with you.

I think the bottom of the inside of the Quark case is not flat, that's most likely why it's hardly touching it, and only on the outer 1/3 edge.

That could explain why so many have heat issues.

WOW I did a bench run of the motor, almost full throttle with 16.5 volts. The motor got so hot I could only touch it for barely 1/2 second.

The esc on the other hand never got warm at all, the heatsink seemed like it was a a couple degrees warmer than it was before i started (10 mins). I looked at the eagletree, it consumes almost 140 watts no load, running just about full throttle, so almost all of that power is wasted as heat, 140 watts is alot!

The heat spreader on the other set of FET's got about 45 C , to the touch, just a guess, but that bottom set just stayed VERY cool.

What temp would the motor be if i could only touch it for 1/2 second? I hope i never got it too hot. :013:

I thought I'd mention the other way. Some people don't like to soldier and mine was brand new and wanted to disturb it as little as possible. This makes it quick and simple without soldiering.

After modded we could call it the 125C, C for cool.

Do you have a temp gun?

How about a temp loop or sensor from the eagle tree?

If I were closer....I could loan them to you for the test.

IIRC, you are NOT supposed to run the motor unloaded for any length of time at full throttle! It could possibly damage the motor! Just thought I'd let you know...

Bye:018:

I know, but i did let off about 10% off full throttle. To keep the rpm safe limit.

ProCharged: I JUST ordered a duratrax flashpoint thermometer for $30, just happened to be on sale too (was $40).

So what is the max safe temp for the 540C 7Xl then? Does anyone know?

Oh, and i forgot to mention. I DO have a temp probe for my eagletree, but I can't get it to read properly, wtf does 6064 mean, it's a straight line. I've tried many times, no luck. :032:

Temp probe or loop?

The probe, the small diode.

Did you use thermal compound with it for heat transfer????

If not then that's probably the issue. If you did then perhaps the probe is malfunctioning.

50 degrees feels like burning your hand already. Having a BL motor run unloaded makes no sense. it's not considered a test, only a way to ruin the motor.

I'm not real swift when it comes to some of these things, but I would think that running a motor on a bench will cause the motor to get hot from the sheer rpms that the motor is turning. Since you were running the motor unloaded, I would think that it wasn't drawing nearly the current that it would while in a truck going around a track during a race. This may have, at least partially, accounted for the esc running so cool.

running it unloaded is very unefficient for a motor, plus the high RPM's can damage the magnets.

This is true.

Running a motor under load increases current draw...more load, more draw.

50 C feels like it's burning your hand? Well, then i would have to say the top heat spreader was only about 30 C then.

ProCharged: I did not use thermal paste, i used electrical tape on the motor, but still, that's not the prob. All i get for a reading on the PC is 6064, or 480 when plugged into the Temp2 socket.

I don't know the specific max temp for the feigao's, but I think I've read most motors shouldn't go above 200f (93c) at max. I don't think I'd want mine any where near that hot though.
An unloaded 7xl on 16.5 v (since there'd be almost no volt drop unloaded) is going to be spinning near 40000rpm..not something I'd be doing to my motor for more than .5 of a second, if that.
It was never going to be a test for the ESC since it was at or near full throttle, and 140 watts at that voltage is less than 9 amps. So I'd be supprised if you felt heat in the ESC with no heatsink.

With the A123's, the max RPM it could spin at no-load would be around 36,000 rpm. Nothing terrible at all.

Here is pic of the CF piece i think i'll use for putting pressure down on the Quark to the heatsink surface.

The loaded speed for a 7xl is 2145 I think, so 2145 x 16.5 = 35400rpm
The unloaded speed is 2382, so 2382 x 16.5 = 39300rpm

Hope this heatsink turns out well for you though. I've recently damged a second Quark with over heating problems. I use the heatsink from rc-monster, one 40mm fan, one 3'' fan and I don't think I was doing anything other the top with it setup wise, yet it still can't do a 5 minute race on 14 cells.

Just to be clear on motor loaded - unloaded business.

If controller can handle it (high RPM) or limit it then there is no harm.
Mechanically Feigao motors rated at 50000 RPM Max (bearing and balancing wise).
Temperature more then 90Deg C is bad because of higher differential temp of magnet (mainly you should worry about magnet) and copper losses. Do not forget about balancing epoxy which can come loose and epoxy holding end-caps.

I am hearing a lot about loaded Kv numbers does anybody knows what the load is? Because there are lots of ways to calculate it and estimate.

With higher RPM current goes up because of inertia of rotor, so their will be RPM when it is less noticeable based on rotor size. And that is where power is dissipated and heat is coming from. And that is another reason not to run BL motors with out load or more correctly without control of RPM.

Well, I did an eagletree test, and what I got was 42,000 rpm max, with a brief full throttle pull.

I can't remember the voltage the eagletree said, but either the volts the eagletree is reporting under load is wrong. OR, the rpm the eagletree is reporting is wrong. I am using the two wire RPM sensor.

Because that would require a voltage of 17.5 volts...... no way! The A123's under a little load will hover around 16 - 16.5 volts.

Well, 2 phases to define RPM is not very accurate, but close enough. If you run this test many times then you can get better averaged value, couple runs is not enough.
5% error will be about 2100 RPM which is good resolution for given sensor pickup.

I have been having voltage reading problems also with my eagletree lately.

It's been approx. 1 volt lower than it should be at max volts. Underload, I couldn't tell you , as there is no way of knowing, right?

Also, I was looking at one of the fans that came off one of the GPU heatsinks. It;s small, very flat, and blows alot, ALOT for it's size.

I am just trying to figure out an efficient way of using it to cool my 7XL. I was thinking of using a shroud (don't know from where, or what :032: ) so it channels the air over the entire circumference of the motor heatsink.

It's a 12 volt fan, and uses 3.3watts, as confirmed with my power supply.

EDIT: I would take the rest of the frame off the fan to mount it.

I just read through this thread and it just dawned on me that I saw a reference to arctic silver. If you are going to be using that stuff on the inside of the case, I wouldn't. Although it isn't supposed to be electrically conductive, I think that a matter for some debate. In any case arctic silver does exhibit signs of capcitance. Like I said, I'm not real swift on these sorts of things, but to me, capacitance or conductor, I wouldn't go wiping that stuff all over my expensive electrical equipment. I'd use Arctic Alumina.

As for the sink, it looks neat, but where are you going to put it. I have had experience with dealing with heat when messing with LED lighting. LEDs get VERY inefficient when you drive them hard and they produce a lot of heat.

Anyway, I've found that there are two ways to get rid of heat. Or move it to another place. The first is to use a big heat sink. What I mean by big, is mass. Say two to four ounces of aluminum. The other way is to increase surface area to promote convection and we do this through the use of fans. The problem with this is that air is a very poor conductor of heat. You have to move a LOT of air for it to be effective. The way that we are using fans is to make up for the use of small heat sinks.

Not to get off on a tangent or anything, but I'm bored, so here I go. You could do a little experiment. Take a piece of metal, like a 5.5mm connector. Hold it up with something that doesn't conduct heat very well, like a clothes pin and then hold it over a cigarette lighter (lit of course, LOL) for about 30 seconds. Get it good and hot and then blow on it and see how long it takes to cool to a point that you can hold it in your hand. Now, do this again, but instead of using a fan, just set the connector down on it's end to get good contact on a thick piece of aluminum or even steel and then see how long it takes before you can hold it. I'll bet that it will cool faster by just setting it down on the "sink" than it does by blowing on it.

Anyway, I like the heat sink that you are making. It looks cool, but if you want a heat sink that big with a lot of surface area, why don't you just mount it to the chassis?

Artur; in some cases the magnets get loose/split on the feigao shafts.

I thought neodymium looses it's power at 110 degree C.

About the load that they put on the motor; they do give the Kv and the current it can 'handle'. i wouldn't be surprised if they used a fixed voltage for some odd reason. or they simple determine the max. load by the resistance/thickness of copper