Connecters

[David]

I have heard from several long time R/C flyers that they change out their battery / esc connectors every couple of years. Saying the get worn and lose good connections after long time use... Something about the gold plating on them. Any comments out there on this issue?

[WintrSol]

RE: Connecters

Quality plated contacts are rated for the number of insertions and separations, to give a life estimate, so it is something to consider, especially with the cheaper contacts commonly available. Still, it takes a lot of connections to wear out a connector; maybe a few hundred or more, with thin plating. If you have more than one battery you use with a given ESC, then the ESC takes most of the wear. Your question has me thinking about examining my connectors with a bright light and strong magnifier.

[Konrad]

RE: Connecters

Also that snap you hear when you connect the battery is wearing out the connector. That snap is from the current rush from charging the input cap of the ESC. It results in a spark that eats away at the connector. Many higher voltage or better quality ESC have anti spark features to protect the esc. I like to use the Jeti style myself.

http://www.jetimodel.com/en/katalog/Accessories/Connectors/


All the best,
Konrad

[Alpha]

RE: Connecters

Hi David, good question. For exposed contacts I'll use a regular pencil eraser to remove some of the carbon scoring which can accumulate on the gold plating over time. In applications with 4s or under, I've never had an aircraft which outlasted the connector, and I've had many planes last 300+ flights. In 6s applications, I inspect the connectors after a weekend of flying, and rub them with the pencil eraser every 50 flights or so for good measure.

As Konrad mentioned, in applications where an excessive spark/snap/pop is extant, I'll consider using an anti-spark module or a simple resistor. This is more for 8s-12s applications, but I have done it on 6s in the past. I wouldn't say it's necessary any of our PNPs, but it doesn't hurt, either.

[Konrad]

RE: Connecters

Good hint about using an eraser to maintain the contacts.

I find the need to use a resistor to control the capacitor charge rate is driven more by the size of the caps than the voltage.

As my power set ups are often driving the power components hard, I have real concerns with ripple current. So I often add a charge resistor along with the added capacitance even when using 3 cells. I have a 150 amp 2 cell application where I also use these anti spark connectors but that is not in the realm of a sport set up.

The fact that you can't remove the pins from the EC-x connector housing make these connectors of little or no value to me. This issue is not unique to the EC connector. The fact that the Anderson Power Pole did have a pin extraction tool made them very desirable.

Note; The resistor is not in line with the power side of the connector. They are used to charge the input caps only.
With the Jeti the male connector shunts the resistor when fully engaged.

All the best,
Konrad
[hr]
Alfa,
I recall you making a post as to why MotionRC does not carry bullet style connectors. I think it had to do with child safety. I can't find this post. Could you please reiterate this position.

All the best,
Konrad

[CT]

RE: Connecters

I may have found my gremlin that I have been looking for the last month. After thorough testing of all components, esc, motors, wiring, and sending my DX9 to Horizon for testing, nothing turned up. Last weekend while binding a bird and subsequent power failure in pre-flight, I examined the connectors on the bat. and ESC, which showed signs of carbon deposits and adverse arcing.

Most of my planes are either 6s or 8s, and these were the ones I was having trouble with, the 4s do not seem to have any issues. I use a Deans series connector for my 8s planes, and these were the most problematic. I am in process of replacing all my connectors with 4mm barrel connectors and xt150's. I am hoping and confident this will solve my gremlin problem.

BTW - I sent my DX9 into Horizon for testing. They tested, repaired a 3-way switch and trim switch and sent back n/c the same day, Outtanding service!!!! MRC and Horizon rocks!
Chris

[Konrad]

RE: Connecters

Give the Jeti a good look. You only need the expensive female end on the ESC. The rest can be your standard 4mm 5.5mm etc. barrel/bullets.
FYI; I don't like the bird cage style male connector. More on this if you want to know, but it will take me some time to draw the sketch.

All the best,
Konrad

[WintrSol]

RE: Connecters

None of my aircraft have higher than 4S batteries, and they are all fairly small (<55"). If/when I fly larger aircraft than need a higher-Voltage battery, I will probably go the the Anderson Power Pole connectors; the contact design makes the arc on one face, before settling onto the main current drawing face, which means carbon-tracking will be less of an issue for contact life. They are kind of large, though, so don't fit well in, say, the FMS P-51.

[Konrad]

RE: Connecters

Here is quick and dirty cartoon as to how the Jeti connector works.

When the male connector is first inserted into the female connector (I hope this isn't too hot :cool: for the management of RCG that might be here) the current to feed (charge) the ESC caps had to flow through the resistors that bridge the internal insulator. As the male connector keeps traveling into the female connector it shunts the resistors when it passes by the insulator. This results in a low resistant connection suitable for motor power currents.

With say a *11.1 volt battery the Jeti connector will allow a controlled current of 171 mA (11.1V/65 Ohm), *130/2=65 ohm. This will not spark!

I have to say that I like to see an Ohm value of around 10 ohm with lower voltage set ups, as some ESC start to count the voltage across these input caps to figure out the cell count for the voltage cut off. *Too low a current flow often means that the caps aren't fully charged when the ESC makes the reading.*

It is considered bad design to charge a cap with no way to control the in rush of current.*

All ESC should have some kind of anti-spark control especially those that have large low ESR (Equivalent Series Resistance) caps. High in rush currents stress the battery, ESC copper traces, and the input cap. Not good design practice.

All the best,
Konrad

[WintrSol]

RE: Connecters

FYI, the guys at Castle Creations recommend against using resistors to charge the caps on their ESCs, mostly because one may boot up before the connection is fully made, causing it to read the wrong battery size. You can get around this by programming the ESC to a fixed battery voltage, rather than auto-detect, though. Designing in an in-rush limiter, which then must be switched out of the input circuit, would greatly increase the size and weight of an ESC, meaning $$$.

[Konrad]

RE: Connecters

That was for the old style of spark arrestor were we use pig tales (old servo connectors) to carry the 5 ohm 1 watt resistors. Plugging in the pig tails then lining up the power connector often resulted in a false voltage reading by the ESC. This is because it could take seconds to complete the hook up. With the Jeti connector the time between insertion of the male connector to the time it has shunted the charge resistors is measure in milliseconds. Well, with in the programing limits of the CC controller. It is a light simple and easy solution to the in-rush problem.

Also if using a pig tailed system be aware that the BEC will start to try to draw current through the charge circuit. If using digital servos this can burn out the resistors as they might not have adequate wattage ratings.

All the best,
Konrad

[Konrad]

RE: Connecters

Thinking it might be time to actually show these connectors

[WintrSol]

RE: Connecters

Granted, reducing arcing eliminates one source of poor connections. This still doesn't answer the question of mechanical wear. MIL spec contacts have a rating for this, but the relatively cheap connectors used in small aircraft probably don't have MIL spec coatings. One wonders how many insertion cycles the connector on the ESC can take, especially the smaller ones.

[Konrad]

RE: Connecters

Like the Tamiya connector of old. Those thin stamped contacts caused so much power loss in early days of electric model flight as they would loose contact pressure in as little as 10 insertions. And this doesn't take into account the loss of contact pressure as the contact looses its "temper" as it heats up.

There is nothing special about Mil Spec's it is just a standard that a component needs to meet. They are there to try to have some minimum uniformity between manufactures. The fact that something meets a Mil spec does not mean it is better or worse than any other connector. It all depends on the requirement of the specification. This is why you often see a part with a list of mil spec's a mile long. You might have notice that mil specs have all but disappeared from modern prints and contracts. This is because the military is not in the business of making things, rather the opposite.

Fretted and pushed back pins are the bane of many full size aircraft Cannon type connectors, heck any connector system.
https://www.ittcannon.com

I often use those Cannon pins and barrels (only) for my lighter contacts. I use heat shrink as my housing (insulators).

To your point that is why I don't like the bird cage stye of connector. The little thin cage will loose its contact pressure a lot faster than that of the finger style of bullet connector.

In real life a quality connector will mechanically out last any battery and model airframe. As we are making "live" connections any data you might find about insertion cycles has little or no relevance. It is that spark and heat that kills our model connector, not the insertion cycles. The spark makes a pitted surface and adds contaminates (carbon and particles) to the contact surface.

So keep the heat down with oversized connectors (low micro-ohm rating) and control the spark with a resistor and clean the contacts with a mild abrasive (the eraser is great).

Coatings? You mean silver or gold plating or anti oxide ( Anti-corrosion Oils)

All the best,
Konrad

[WintrSol]

RE: Connecters

Yes, MIL is a minimum standard, but our contacts have no standards applied, so that pretty gold 'plating' could just be a flash coating, like cheap jewelry, and not be a good plated surface. I've yet to find any documentation on connectors commonly used in models that even hints at the quality of the coating, which may not be a plated surface.

Yes, the type of contact has a real effect when you approach the current limits. Many have reported the collapse of the spring in a Dean's plug from overheating. I've had the spring in servo connector contacts collapse, causing all kinds of servo and receiver problems; sometimes they were made that way.

[Konrad]

RE: Connecters

The old Futaba "G" connector, no sense betting around the bush. And yes we as hobbyists often are using industry connectors at way over their amp limits. Sermos connectors did publish data as to the silver thickness of their 30 and 60 amp rated (by them) connectors. When looking at any electrical component duty cycle needs to be factored in when looking for useful life figures.

[Konrad]

RE: Connecters

You make a good point about the Deans Ultra plug (T style plug). The plastic housing provides the purchase for the spring contact. It is not self contained in the conductive contact. Over heating the housing, melting the spring’s purchase allows the spring to move away from the contact. The number one cause for this failure is using too small a soldering iron. Small soldering tips lack the thermal mass need to heat up the contact fast enough to melt the solder and keep the housing cool. Heat guns also have this issue in that the tip doesn’t have enough thermal mass and cools down way too fast when placed on the soldering pad of the contact. Now the issue isn’t the wattage rating of the soldering iron but the thermal mass of the soldering iron’s tip.


A hint to help keep one from damaging the connector on the bench before it even ever flies, is to solder the leads with the corresponding connector plugged in. The other connector acts like a heat sink to carry away the heat after you have attached the leads with solder.


All the best,
Konrad

[WintrSol]

RE: Connecters

You make a good point about the Deans Ultra plug (T style plug). The plastic housing provides the purchase for the spring contact. It is not self contained in the conductive contact. Over heating the housing, melting the spring’s purchase allows the spring to move away from the contact. The number one cause for this failure is using too small a soldering iron. Small soldering tips lack the thermal mass need to heat up the contact fast enough to melt the solder and keep the housing cool. Heat guns also have this issue in that the tip doesn’t have enough thermal mass and cools down way too fast when placed on the soldering pad of the contact. Now the issue isn’t the wattage rating of the soldering iron but the thermal mass of the soldering iron’s tip.


A hint to help keep one from damaging the connector on the bench before it even ever flies, is to solder the leads with the corresponding connector plugged in. The other connector acts like a heat sink to carry away the heat after you have attached the leads with solder.


All the best,
Konrad

There are a few guys who have had them fail in use from overheating - running 100A through a 30-50A connector will do that, especially with the cheap substitutes. The genuine Deans Ultra plugs are made of a plastic that will tolerate a higher soldering temperature than most of the knock-offs, but, yes, if your iron has too small a tip and/or too few Watts, by the time the solder melts properly, the plastic is often done. Same for the XT plugs; I find they are much more susceptible to deformation during  soldering than the real Deans, and when they do, they are really difficult to un-mate.

[Konrad]

RE: Connecters

Yep, and then these guys cry after over amping the connector about how poor the Deans Ultra plug ( 'T' style) is!

I too have noticed that the genuine Deans Ultra plug is far superior to many (most) other "T" style connectors. With the knock offs usually identified by their darker red maroon color the plastic housing melts a lot sooner than the genuine Deans. Also I've seen issues with the burs on the edge of the contacts that don't allow full face contact with the mating connectors contact. This result in a high resistant joint that allows for low currents to flow (like the BEC) but cuts the motor out as you try to throttle up.

I wonder who supplies the 'T' fitting for the Admiral batteries. They look to be the higher quality lighter red ones. In my case I'd prefer that all electrical power connectors by supplied loose or not at all. I spend far too much time straightening out what is supplied to me in these Plug & Play type models. Like the EC-x connectors I have to destroy the housing to add those pig tails!
http://www.motionrc.com/admiral-4500mah-6s-22-2v-40c-lipo-battery/

All the best,
Konrad