MMM V3 problem with heatsink - RC-Monster Forums

Topas · 06:08 PM

Today I received my MMM V3 :

No comment :

Topas · 06:16 PM

Comment :

Two connectors touch the heatsink at the same time ... I think you can imagine what will happen if I connect the LIPO to the ESC...

As I am from germany it is very expensive to send the ESC back to CC-service ...
I thought the MMM is ready to run. What should I do ?

BrianG · 11.04.2008, 06:16 PM

Again, Patrick (from CC) said they were unable to simulate problems with the HS touching the bullets, even when they removed the HS anodizing.

If you still feel nervous about it (as would I), see if you can slip a piece of lexan between the bullet and heatsink to act as a barrier.

emaxxnitro · 07:54 PM

or shrink wrap the bullets! i dont know why castle does not solder wires to the pcb. then put there oversized bullets on the wires. its a proven method! cough (mamba max) cough.

SpEEdyBL · 11.04.2008, 08:17 PM

More solder joints? More radio interferience? Less flexibility in the wires going to the motor? Less spectacular looking? Maybe that's why.

It's not rocket science to prevent a short and the anodizing of the heatsink is not even electrically conductive. Patrick @ Castle creations insists that the bullets touching the heatsink is not a problem and never was.

lxmuff · 11.05.2008, 08:10 AM

Quote:

Originally Posted by SpEEdyBL

More solder joints? More radio interferience? Less flexibility in the wires going to the motor? Less spectacular looking? Maybe that's why.

It's not rocket science to prevent a short and the anodizing of the heatsink is not even electrically conductive. Patrick @ Castle creations insists that the bullets touching the heatsink is not a problem and never was.

He usually admits to issues they have had, but a novice at this hobby understands the short problem. If they touch at rest, they will rub dynamically and eventually short after the coating is worn off.

I have two friends that just sent theirs back because of the short. One even hurt the battery. Some of these don't have any room to put lexan like mine, so I just removed the bullets all together.

brushlessboy16 · 11.05.2008, 08:40 AM

For the second time in this thread.
From the President of Castle creations, Even if the coating is worn off, It will not short

Topas · 11.05.2008, 08:54 AM

Quote:

Originally Posted by brushlessboy16

For the second time in this thread.
From the President of Castle creations, Even if the coating is worn off, It will not short

Why ? In my case it will short ! There is not enough room to put a piece of paper between the bullet and the heatsink....

Never mind - last night I tried the MMM instead of my MGM 22418 in an Losi 8ight-E. I experienced a little more cogging in comparison to the MGM - but it is not bad at all.

RC-Monster Mike · 11.05.2008, 09:29 AM

Quote:

Originally Posted by brushlessboy16

For the second time in this thread.
From the President of Castle creations, Even if the coating is worn off, It will not short

Patrick said that they could not duplicate the short in this case, and hadn't witnessed it. That doesn't mean it can't happen (and IMO eventually it will happen if both bullets are touching the aluminum conductor - it is only a matter of time). Personally, I would not even consider running a controller that has this potential issue beyond initial testing - I would address it before any extensive driving. I don't care who says its OK - it looks like a short waiting to happen. I suppose if(when) it does short, it will be covered by warranty, but the batteries won't be covered(or the chassis and melted Lexan body). Just my opinion based on 8 or so years of brushless car/truck use. :)

Topas · 11.05.2008, 10:09 AM

Quote:

Originally Posted by RC-Monster Mike

Patrick said that they could not duplicate the short in this case, and hadn't witnessed it. That doesn't mean it can't happen (and IMO eventually it will happen if both bullets are touching the aluminum conductor - it is only a matter of time). Personally, I would not even consider running a controller that has this potential issue beyond initial testing - I would address it before any extensive driving. I don't care who says its OK - it looks like a short waiting to happen. I suppose if(when) it does short, it will be covered by warranty, but the batteries won't be covered(or the chassis and melted Lexan body). Just my opinion based on 8 or so years of brushless car/truck use. :)

Dear Mike,

thank you very much for this statement. I drive brushless boats, cars and flying objects ;) for years and I always use my own brain.

Look at the images I have taken of my V3 MMM and you will see that the battery side of the bullets hit the heatsink. This is a very serious problem - and that is the reason why I wanted to warn other users.

Dagger Thrasher · 11.05.2008, 08:39 AM

No offence, but after all the issues the MMM has had and all the work Patrick/CC have done to get them up to scratch, I *seriously* doubt that Patrick's about to let thousands of MMM V3s leave the factory if they apparently have such an obvious flaw. If there actually was a problem, there's no way he'd be daft enough to say there wasn't after they've tested the issue to death.

Besides, electricity will always take the path of least resistance. The MMM has 0.0003 ohms per phase resistance, which is probably considerably lower than that of the aluminium heatsink (even with the anodizing worn away), so won't be an issue. What happened to your friend's battery?

Sorry, I'm not trying to get on your case! It's just that Patrick has explained and stated that this isn't a problem and has never denied any of the issues that presented themselves in the past...so I just think we should perhaps (IMO) take his word on this one. He's the electronic engineer.

BrianG · 11.05.2008, 11:03 AM

Quote:

Originally Posted by Dagger Thrasher

Besides, electricity will always take the path of least resistance. The MMM has 0.0003 ohms per phase resistance, which is probably considerably lower than that of the aluminium heatsink (even with the anodizing worn away), so won't be an issue. What happened to your friend's battery?...

That statement is not totally true. Assuming the battery is not completely shorted (causing all the battery voltage to drop across the battery's internal resistance), a partial short will cause some current to go through the heatsink and some to go through the load (ESC/motor). True, more current will go through the path of least resistance, but not all.

Look at it like this: If the load presented a 0.25 ohm load, and the heatsink partial short is 0.01ohms, 96.15% of the current will go through the 0.01ohm heatsink "load", while the other 3.85% will go to the real load. Of course, in reality, the battery voltage will drop substantially even with a partial short...

I still don't think the HS/bullet proximity is "safe" IMO. But, even if the HS did partially short out the bullets, the contact area would not be ideal and the resulting arcing will eat away at the offending contact.

Dagger Thrasher · 11.05.2008, 08:58 AM

Just because there seems to be metal contact between the bullets, it doesn't mean it's going to short.

Do you have the latest software? With 1.20, the MMM should be smooth as melted butter.

Jabe · 11.05.2008, 09:07 AM

just bend heatsink, so that it doesnt touch battery leads, as that could cause your monster and lipo to burn, as they shortcircuit, but leave that motor side as it is.

11.05.2008, 09:17 AM

My opinion on this..... castle whether or not it will short needs to work on its quality control. there is no reason some one should have to bend a heatsink or stick something in between it. how hard is it to take 30 seconds to look at each unit before the case gets put on. i give them credit for fixing alot of the issues but there are still issues that are present.