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Old Mar 27, 2012, 11:33 AM
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Castle Bullet Connectors

I normally use Neu 6mm bullets for my battery-ESC connections. But I built up a plane for a friend of mine running a 200+ amp setup (Mega 22/60/1E, CC ICE 200, TP 7S 4400 65C) and we took it flying this past weekend.
He wanted to use Castle 6.5mm bullets because the LHS has them and they'd offer a little more current capacity than my Neu 6mm bullets.

During build and setup, I noticed the CC 6.5mm connectors are VERY tight to get plugged in, but when about halfway mated together, they get very loose, where they can wiggle and slide apart with very little effort.

Has anyone else found this??

The increased resistance of the loose connection is one concern for me.

But the biggest thing is that during the most recent flight, the ESC reset itself in flight. We heard the initialization chimes and cell count. Of course, no power during this restart!
A bit unnerving on a plane with a huge wing loading and the glide slope of a truck tire.

A look at the data log confirmed the restart, and there was no low volt, high amp, or other type of cutoff. Just restarted.

I have something of a trust issue with these connectors now.
Any thoughts are appreciated, as well as any good solutions.
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Old Mar 27, 2012, 11:52 AM
Tim Lampe; Hobbico R&D
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Champaign, IL
Joined Dec 2009
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I am using Castle 4mm bullets on my Sunracer that I set up last year. All of the bullets in the first three or four packages I orderd were IMPOSSIBLE to join together--way too tight. I was disappointed because they look like nice quality. I ordered several more packages (from our warehouse stock) and cherry-picked some good ones I could use.

They've been working great, but I did have to rummage through several to find enough good sets for my batteries.

Tim
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Old Mar 27, 2012, 12:50 PM
The props of tomorrow
Varna , Bulgaria
Joined Feb 2007
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All 6mm connectors I have and I ever bought were very tight. So tight you cannot join them , and if you join them you cannot separate them. I use a 6mm lathe collet to press them until they start to join easily , but tight as well.
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Old Mar 27, 2012, 01:03 PM
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By design, this type of connector makes contact only at the tips of the "fingers" which are flared out to a larger diameter to provide the spring force. This is why they are so difficult to get inserted, but once connected, they slide and wobble easily. What you describe sounds normal and I suspect your reset problem is due to a very bad solder joint or broken battery contact somewhere.
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Old Mar 27, 2012, 02:00 PM
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Quote:
Originally Posted by vespa View Post
By design, this type of connector makes contact only at the tips of the "fingers" which are flared out to a larger diameter to provide the spring force. This is why they are so difficult to get inserted, but once connected, they slide and wobble easily. What you describe sounds normal and I suspect your reset problem is due to a very bad solder joint or broken battery contact somewhere.
So "sliding and wobbling easily" couldn't be a cause for a brief connection loss?

I do notice the flared fingers of the male connectors. But this should result in a constant pressure as it slides into the female connector.
Since the pressure relieves as the male slides in, it seems to indicate the female connector increasing in diameter as it gets deeper

The ESC and battery are brand new, and the solder joints are well-soldered.
I know ESCs do occasionally do bad things but want to investigate the bullets, which are a red flag in my mind.
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Old Mar 28, 2012, 01:12 AM
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United States, WA, Redmond
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Go to pep boys and buy soe conductive greece, it makes it much easier for connection.



btw real men use 8mm connectors
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Old Mar 28, 2012, 02:22 AM
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Quote:
Originally Posted by murdnunoc View Post
I know ESCs do occasionally do bad things but want to investigate the bullets, which are a red flag in my mind.
Murdo,
I have found that a marginal main battery connection can cause false error messages in my ICE controllers and cutouts: http://www.rcgroups.com/forums/showp...1&postcount=38 and http://www.rcgroups.com/forums/showp...3&postcount=58

I've also had the tolerances on some CC connectors I've bought to be excessive to the point of being unusable and had to be binned.

When they are good, they're good but when they are bad, they're horrible!
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Old Mar 28, 2012, 07:07 PM
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Quote:
Originally Posted by vespa View Post
By design, this type of connector makes contact only at the tips of the "fingers" which are flared out to a larger diameter to provide the spring force. This is why they are so difficult to get inserted, but once connected, they slide and wobble easily. What you describe sounds normal and I suspect your reset problem is due to a very bad solder joint or broken battery contact somewhere.
I think you are speaking from your own experiance and are possibly not open to the idea that there might be some low quality connectors out there that don't really cut the mustard.

To me it sounds possible that the holes inside the female connectors could well be a bit wider deeper down leading to the problems described. Should be easy to figure out with a pair of calipers.

Funny that it should be the CC connectors and not the Hobbyking ones.

From the many Hobbyking 6mm gold connectors i have used, i have had 1 or 2 where the cuts where not nicely lined up but the other 98 of them where just fine and good for competative F5B (300A+) use.

I do plug them in and out 10-20 times with a pair of pliers before i even turn the soldering iron on.
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Old Mar 28, 2012, 07:16 PM
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With the 6mm HK ones, which I rate highly, if they are too tight you can squeeze the fingers in gradually with pliers or similar until you get the desired friction fit. Well that's what I had to do because they were impossible to separate once connected!
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Old Mar 28, 2012, 07:42 PM
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Quote:
Originally Posted by Peter M View Post
Murdo,
I have found that a marginal main battery connection can cause false error messages in my ICE controllers and cutouts: http://www.rcgroups.com/forums/showp...1&postcount=38 and http://www.rcgroups.com/forums/showp...3&postcount=58

I've also had the tolerances on some CC connectors I've bought to be excessive to the point of being unusable and had to be binned.

When they are good, they're good but when they are bad, they're horrible!
Peter, I believe I've run into the same issue you have. And it's a face-palm moment because I had your problems in mind when I set this thing up. Hoping it "wouldn't happen to me..."

Quote:
Originally Posted by jjmouris View Post
To me it sounds possible that the holes inside the female connectors could well be a bit wider deeper down leading to the problems described. Should be easy to figure out with a pair of calipers.

Funny that it should be the CC connectors and not the Hobbyking ones.
I can measure the outside of the connector, but measuring the inside deep in the socket I don't know how to do. If the inside diameter really is larger than the outside diameter, then the only thing I'd be able to get with my caliper would be the I.D. right at the rim.

It IS the only explanation I can see, though, for the connector being tight initially, but loose once it's fully plugged in.

The Male connector does have a visible flare to the prongs. But it seems to not be enough to compensate for whatever flare there is to the female connector.

It seems also that it would be incredibly tough to machine/cast these female connectors with an inside diameter that's GREATER as you go deeper into the cylinder. But I guess that's not something for me to worry about...

Quote:
Originally Posted by DownUnderPilot View Post
With the 6mm HK ones, which I rate highly, if they are too tight you can squeeze the fingers in gradually with pliers or similar until you get the desired friction fit. Well that's what I had to do because they were impossible to separate once connected!
I use HK 6mm bullets interchangeably with my Neu connectors. Love em!
I've had to squeeze opposing prongs on the male connectors, too. But I'd rather have a connector that starts too tight than one that can't hold a connection!
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Old Mar 28, 2012, 07:48 PM
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Right now I'm torn as to what to do about the issue.
I just plugged the plane up on the bench and started wiggling the battery connectors (pretending I was going through the air at 200mph )

It took a little while, but I did get the ESC to reset just by wiggling the connectors while fully plugged in. They're just too loose.

I can expand the Male connector with a knife blade to the point where it holds a tight connection, but then they're too tough to even plug in.

The only option I see short of an entire power system connector swap is to modify the connectors.
Maybe sanding a little cone shape onto the nose of the Male connector?
Combined with chamfering the lip of the Female connector?
Maybe that would make them possible to plug in, while still having the Male expanded enough to make solid contact deep in the socket.

But maybe that would be just as much work as a night of soldering to switch to Neu 8mm connectors.
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Old Mar 28, 2012, 07:54 PM
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Joined Mar 2004
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It's reasonably easy to deliberately or accidentally machine the female sockets with an increasing radius since this type of machining is typically done on a lathe with a boring bar (single tooth drill bit of sorts). If the boring bar is fed in at an angle it will drill an expanding hole.

That said, I still think it's unlikely. Parts almost always err on the other end of the spectrum (flared opening) due to eccentricities in the tools or machines. But if you have metal calipers, give it a shot (with caution against shorting). Lock them at the I.D. and see if they wobble inside.
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Old Mar 29, 2012, 04:56 AM
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Originally Posted by murdnunoc View Post
But maybe that would be just as much work as a night of soldering to switch to Neu 8mm connectors.
Why switch to 8mm?

Don't you have any 6mm? Time to order some more from Hobbyking or Neu?!
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Old Mar 29, 2012, 08:33 AM
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Originally Posted by jjmouris View Post
Why switch to 8mm?

Don't you have any 6mm? Time to order some more from Hobbyking or Neu?!
I do have a whole pile of 6mm connectors. But didn't feel great about them at 200+ amps. I'm sure they'd be OK. But the battery wires are already longer than I'd like so I'm going for every resistance drop I can get
There's not really any installation space issue, so I see the 8mm bullets as a benefit with no drawback.
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Old Mar 29, 2012, 08:48 AM
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Quote:
Originally Posted by murdnunoc View Post
I do have a whole pile of 6mm connectors. But didn't feel great about them at 200+ amps. I'm sure they'd be OK. But the battery wires are already longer than I'd like so I'm going for every resistance drop I can get
There's not really any installation space issue, so I see the 8mm bullets as a benefit with no drawback.
We use them all the time for high current applications in F5B that can be over 400 amps.

Steve Neu
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