MMM V3 problem with heatsink

[lxmuff]

Originally Posted by bl-is-future

i know you said it would be a pain to send it back but if you adjusted the software and you still get cogging it is not right. that esc is so smooth you could rub on your babies ass. Figuratively speaking of course.

The esc is very smooth for what it is. If you do have cogging, look for your connections etc.

As far as what Patrick said....That's nice but with then MMM on Version 3 since this past May, they still may not have gotten all the issues worked out.

As far as the resistance question with the path of least resistance, if your battery side bullets are short to the heatsink and you plug in your battery with the switch on the controller off ..... the esc circuit is virtually open.

[Topas]

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]

As far as the resistance question with the path of least resistance, if your battery side bullets are short to the heatsink and you plug in your battery with the switch on the controller off ..... the esc circuit is virtually open.

That's a good point, I hadn't thought of that. Touching bullets shouldn't be a problem on the motor side then, but if both battery bullets are touching when the ESC's off/not moving, then I guess it's a potential hazard.

[Topas]

Originally Posted by lxmuff

The esc is very smooth for what it is. If you do have cogging, look for your connections etc.

As far as what Patrick said....That's nice but with then MMM on Version 3 since this past May, they still may not have gotten all the issues worked out.

As far as the resistance question with the path of least resistance, if your battery side bullets are short to the heatsink and you plug in your battery with the switch on the controller off ..... the esc circuit is virtually open.

Yes it is smooth .... but compared to the MGM it could be better ;)

[TexasSP]

If your MMM is not smoother than your MGM, you are doing something wrong. I have owned both, and the MMM is far smoother period. The MGM could never even run my 6 pole align motor and had issues with the 4 poler even with the latest firmware. The MMM ran the align as smoothly as it runs the neu. Not to mention that the braking on the MGM's leave much to be desired as do many of the other settings.

My opinion is if you don't like the MMM design still, sell it and run the MGM. All of the hand wringing is just a waste of time. Meanwhile I really enjoy running my MMM V2 with the latest firmware immensely.

Either way, it's not like the MGM's never fail either.........

[BrianG]

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]

Ah, ok. I stand corrected. I must admit, I still prefer the V1 setup of wires with bullets; it's less of a problem if you have a motor with short leads.

[RBMike]

Just bend a couple of the heatsink fins. Put some shrink tube on the bullits, you'll be fine & not have to think about it all the time.

[Semi Pro]

just fix the problem and remove the bullets

[BrianG]

Originally Posted by Semi Pro

just fix the problem and remove the bullets

That will probably void the warranty...

[lincpimp]

Originally Posted by Dagger Thrasher

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.

Nothing against CC, but they have still not cured the fan wiring issue. Simple fix to do when you get the esc, but something simple like that should be addressed before the case design was finalized. The MMM design and case are quite a bit different to CC other products, save for the sidewinder. No enough clearance, or a specific area for the fan wire.

Not trying to say that you are wrong Dagger, but the MMM is not perfected yet... I still see flaws that can cause the unit to stop working, or at least not survive for a sufficent service life without failure.

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. :)

Well put Mike, all the testing in the world will only show up some problems. The proximity of the bullets to the heatsink is an issue, the heatsink needs to be smaller, or the board needs to have a bit more room in those areas... I like the bullets on the pcb, at least on the motor side.

Originally Posted by hoovhartid

pedifile...

"1. pedifile
Michael Jackson, R. Kelly
Dont go to Neverland Ranch "

First entry in the urban dictionary, made me laugh a bit...

[Jabe]

as castle said, it doesnt matter if those plugs on motor side touch heatsink, so lets leave that side as it is.
but certainly do something about those battery plugs, as they will shortcircuit and will damage your batterys.

why cant they just replace those damn plugs with wires...

[BrianG]

Originally Posted by Jabe

as castle said, it doesnt matter if those plugs on motor side touch heatsink, so lets leave that side as it is.
but certainly do something about those battery plugs, as they will shortcircuit and will damage your batterys.

why cant they just replace those damn plugs with wires...

Huh? If the HS does happen to short against the HS, it would definitely matter. You'd be shorting the offending phases together and probably damage the FET(s). I don't think Castle is saying it's ok for the motor connections to touch, they are just saying they could not get the HS to actually short the phases.

But yes, I agree, get rid of those silly plugs and use wires instead. I think they want to use bullets because their CC-Nue motor will have wires with bullets on the end and will offer more of a plug-n-play setup as opposed to soldering anything.

Or maybe use solder-posts (like Mtronics) or thick tabs (like Novak) on the motor outputs instead since they will be smaller in diameter and have much less chance of touching the HS. That way, people wouldn't be soldering directly on the PCB...

[rootar]

why cant they just put a SLIGHTY shorter heatsink on it? that basically sets it 3mm away?

[BrianG]

Probably because they already have a bazillion of them made...