Bullet connectors - How to tell good from bad?

workaccount

Hi,
Just wondering is there quality brands or anything out there for bullet connectors?

Also looking to get some soldering wire - any specific brand to look for?

Thanks.

syl77

Use gold plated bullet connectors and good quality soldering wire with flux in it....

coolwings

The metal under the gold plate varies. The good ones have extremely low resistance metal (I think it's berillium copper but a long time since I was interested) under the plating, the cheapies are I believe steel with higher resistence, though they look the same.

The resistence of the connector is what matters. Good manufacturers provide this specification for the products they sell.
If you buy from reputable suppliers who know their stuff and have standards, you don't have to worry about this stuff. Their quality control does it for you.

To give you an idea how far this goes, at www.greenhobbymodel.com we even look for tiny air vent holes to allow the male plug to be pushed on easier. The reverse end (soldering end) also comes in different sizes.
If they are available (not in all sizes) we would have chosen plugs with transverse holes in the solder end so that if required they can be soldered on at 90 degrees to the cable where compactness is important.
Every item has it's variations, relative costs and qualities. Our customers don't consider those things, we do it for them, they can then concentrate on the models.

Each seller will have a policy which you can readily identify, ranging from "stack 'em high sell 'em cheap" to "works perfectly and has spare capacity if required" to "don't know about that we just have these ones".

If you pick a seller that suits you, that way you will be happy until/unless you change your own priorities.

coolwings

Workaccount .... Yes flux is definitely essential.
For large items like connectors I suggest you should try adding flux separately. After trying it once you will never go back .
Solder with flux inside it is more suitable for little items like diodes, resistors, etc, very precise, very neat.
But not so suitable for these connectors that carry the heat away fast and are also subject to strong mechanical loads (pulling plugs apart by the wires) and flexing in use later.

Use a minimum 80W iron, preferably a 100W iron.
Good high conductivity cable carries the heat away as fast as a 40 watt iron can put it in, and dry joints sometimes occur. Adequate power eliminates these issues and makes the soldered work consistent.

A 40W can just about do it if you have a high mass tip, like a hammerhead tip. An 80W is better. I prefer 100W because it gets up to working temps faster, and use a high mass tip as a matter of course. The correct iron will do a 1 - 2 second job, lifting off by or on 3.

loopingfred

Hey there,

Well, going to be a big old debate !

I use PK, or bullet plugs for a number of years now (Joe is more a Dean type, but I much prefer the way to solder a PK, easier for my big fingers ! ), and to be honest, between a really cheap set, and the expensive stuff ( like the hyperion stuff, "real" PK gold plated and so on...) I really don't see any differences !
And that, for a parkflyer use, up to the 90 amps applications (I don't have bigger... Yet )...

So, one day, just to be sure, as perception is one thing, but numbers in some case are real proof, we did plug a wattmeter on different sets of plugs (4mm bullet type)
Expensive set, and cheap stuff... And as far as the meter goes, no difference (with a 0.10 resolution) except for the one induced by the battery itself, but changing plugs in one particular battery don't show anything, so as the temperature (but that one, is the kind of thing that might need to be ran on much longer time, and in flight maybe... ).

So, or we've got really lucky with the cheaper stuff (who knows.. PK ("real" ones) might be made on the same factory as the cheaper one, just rebranded, like a lot of things...) or we need a more decent laboratory certified wattmeter and gears, but in this case, only if you do hardcore competition you might see a difference... Only if you have the instruments to measure it. For a sunday flyer/driver like certainly 99% of us, I don't really see any benefits or avantages to use one or another.

I thing we did debate that matter a while ago

The all plug thing, is part of a chain, you have everything to take care of !
Quality of the soldering, the solder itself, quality of the wire etc etc if you really want to get into it and gain this 1%.
But as Norman said, you can always go for the branded hand tested plugs, no arm anyway, and will give you peace of mind And also, same as Norman, go for a 100w iron and separated flux from the start ! Much better than anything else.

My 2 cents worth of comment

Fred

coolwings

Fred's point about the "sunday flier" part is well considered advice.
Low amp fliers tootling about with a high wing will never notice the difference if their plane is set up half right.
If a flier has too few cells, as in their power comes from very low voltage pack, then their amps must be higher to compensate. This brings their model (measured in amps used) up the power scale, even though it's not a high power model. So that is why experienced electric fliers usually have more cells and fly higher voltage ... so they are also on lower amps, with less heating of the components. Everything lasts longer if you cook it less.
That leaves the competition fliers. Where is the dividing line between quality and trash that will let you down? I can only say my planes don't let me down! I'm sure Fred can make the same claim too.
I did have a friend who flew pylon racers. Not in competition, but still competition planes all the same. He had an unexpected crash while in level flight, which appeared as if radio interference was the cause, as in the control failed, then the engine stopped, then it crashed.
On inspection of the crashed model, it was found that the wires had unsoldered themselves during flight! I suppose he would have been over 90 amps, and possibly brief pulses of 100 A - 120 A. His plugs were of good type all along, but the wires heated to the point where the solder got soft. So he uses a thicker better quality of cable now - 4 sq mm low resistance.
Not a common complaint of course, but it happened to him and wiped out a 200 euro airframe, and much of the stuff inside it too.

So it all depends on what you are doing, and how your gear measures up to what you do with it.

I might have a Kontronik 30 amp ESC in a plane that repeatedly does 40A. But if I do I know how long to leave the throttle up in that high zone, never more than 30 seconds. Another 30A esc might only survive 10 seconds of that. I would definitely have a veritable hurricane of cooling air directed over the ESC in such a model, another guy who copied my setup might not see little airholes, or realise that the ESC does not "just happen to lie in such a spot" I stuffed it there to catch a draught.
That is not a make up example, I recently had an Aeronaut Twinspeedy flying on 25A with a Kontronik 18A ESC. I flew it hard that way for a year, as long as the plane lasted. I still have the ESC in another model working perfectly.

Different makes have different degrees of conservatism in their labelling.
For instance I would expect to get more from a KOKAM 30C than a Thunder Power 50C lipo. I would expect a Seahan 30C to get within 1 amp of the Thunder Power 30/50C, and at a much better price.

Or another situation:
Take two EScs, both 40 amps but different makes.
One has a 5 amp BEC the other has a 2 amp BEC.
The bigger BEC can happily feed 4 - 6 servos. The other one might blow with over 4 ordinary servos, or with 4 high torque servos. It is not suitable for power hungry digitals. So for a 35 amp plane with 2 x aileron servos, 1 x rudder, 1 x elevator = 4 servos + ESC throttle. The servos are digital.
Despite the plane being only using 35A, only one ESC can do it alone.
The other ESC needs to have a small receiver battery added to the plane, and it will then work fine.
But if used alone that ESC will blow if you pull snap rolls or maneouvers that start the servos moving simultameously. BAM! The plane jumps to full throttle.
The "lower" ESC was OK all along, just needed the rx battery as well.

Over time you learn where the redline limits are, sometimes the label tells you all you need to know, sometimes it doesn't. Until then it is wise to allow a little spare capacity in model components.

If you are reasonable about these you won't become the "once bitten twice shy modeller". This species of modeller once had a equipment failure and is never going to have one again! Now insists on a 100 amp ESC, for every model! Only digital servos will do! Dual conversion receivers where they are not necessary, and PCM or 2.4Ghz where no interference exists, etc, etc. Glow engine heli fliers are particularly susceptible to infection with this modelling complaint.
Opposite disease to the "large scale on a reasonable price" species of modeller. These ones fly 1/3 scale models with converted gasoline engines (petrol is cheaper than model fuel!) pouring out interference. They blow three single conversion receivers in 6 weeks, put standard servos in the model ("I used the deluxe ballrace ones which cost me an arm and a leg"). Their big model has one receiver battery and one switch inside running everything. Can tune engines so is not the same as the "holds the club record for most helpers standing around their model when the engine finally starts" sort. :pac:

Subject of a new thread maybe!

loopingfred

Hey Norman

Yeah, agree with all of the above anyway.
In electric flying, whatever the size of the model etc etc, you have to consider the entire chain of component in your installation. And the possible limits of the hardware :rolleyes:

Not only just one factor for one single piece of hardware.

I knew a few guys flying F5B at relatively high level, and they never really cared about the install... Which it was a bit weird to me at the time, but if you consider the chain of hardware involved in the overall performance, I finally get the point of all that...
Just between a ESC and a battery, how many different solder brand and characteristics you will have ? Wire size and resistance... Plug resistance ( even if they all look the same, come from the same source etc etc !)etc etc, so as they say, changing one component to make it the ultime one in the chain is useless, and they don't really have time to build everything themselves ! (the only real solution if you want a perfect material / chain of hardware). Not sure if I'm clear here, but I'm sure you get the idea

Anyway, this is all far away from the sunday flyer that I am ! But as a "standard" user, you will never see any difference from one type/brand to another, I can almost guaranteed that, but I also totally understand people/flyers who try to get the best out of a given material, even if it's to gain a few %, this is also part of the fun of this great hobby !

Interresting debate IMO !

Fred