steelbikeguy

I've been using these professionally and personally for nearly 30 years, and haven't seen any sort of construction like that. Haven't seen any failure of the socket at all, and I'm not very nice to my bike.



The machines that I was designing electronics for are treated much worse!
edit: Here's a screen shot of the cover of the catalog for this series of Amphenol connectors. The pics along the bottom show what sorts of machinery/equipment use them, and what sort of reliability is expected.





Steve in Peoria

2_i 

Am I confusing them with some other ones, that you also might have recommended in the past? The design I remember was just like a miniaturized version of a banana plug with springs strips along the plug for a tight grip. The problem with the miniaturized version was that these springs were getting so thin that they crumpled if the situation was getting tight, making the connector useless. Another problem was that the grip was not always tight enough and the connectors disconnected and there was no way to fix it, unlike for 2.8mm. The soldering was one more handicap, in that the connector was not gripping the wire insulation, and the responsibility for strain relief was shifted to the heatshrink. Finally, there is a benefit in uniform standards and 2.8mm is already there for different lamps.

steelbikeguy

I'm not sure what connectors were causing so much trouble, but I don't think it was the Amphenol pins & sockets that I suggested.
As far as strain relief, the connector shell is designed to handle that. Without the shell, heatshrink tubing does a reasonable job.

I suggested these as in-line connections that were easy to disconnect and would come apart easily for wheel removal.

Steve in Peoria

noglider 

@steelbikeguy, thanks a lot, Steve. Great stuff.

2_i 

OK, I found the offending circular connectors that get frequently get highlighted in the context of bikes, but that can lead to the problems I mentioned. They are in particular distributed by Velo Lumino as 2mm banana plugs. I am still away from my base to check my stock directly, but from my receipts they should be the same as TE Connectivity/AMP 205089 and 205090. The TE Connectivity drawings do not show the springs that are the fragile elements, just like the figures for the connectors you recommended, but you can see those springs in the Velo Lumino photos - these have been the source of my concern.

steelbikeguy

The TE part doesn't seem to be the item sold by Velo Lumino....



I don't have any experience with the Velo Lumino parts. They look like very small banana plugs, and banana plugs are usually only used in lab environments. They seem like an odd choice for use in a dirty, wet environment like a bike. OTOH, if Anton was getting a lot of bad feedback from customers, I would think that he'd quit selling them.

Some time ago, a Bike Forums member recommended the smaller family of the Amphenol connectors, the ATM family. If you wanted to use fully sealed connectors, this would be an option.
The receptacle... (the link to the Digi-key page)
and the plug...

of course, this is still pretty bulky. The receptacle alone is 41mm long and 16.6mm wide (as shown in the print)

Steve in Peoria

unterhausen

I think banana connector is a bit misleading, the construction is similar but they are not much like the lab banana connectors. The lab connectors are a bit sloppy and get worse over time. The connectors I got from Anton have worked fine for me. That kind of plug is often used in rc aircraft with success. Typically they will be very near the motor, which isn't usually a particularly benign environment. And the Supernova connectors are very similar. Like I said upthread, the biggest problem I have had with those is disconnecting them after they have been in service for a long time. There is a lot of surface area.

I think any connector that is going to work has those springs, it's just on many connectors they are on the female side. I don't see how one is much better than the other

2_i 

Oh-oh, sorry for the confusion. I got back home and could check my stock. The problematic circular connectors are indeed used for RC motors and, outside of Velo Lumino, offered, e.g., here. I found the TE/AMP 205089/205090 and they indeed lack those springs. For me, when there was a snag in putting the plug into the receptacle, the spring could crumple up into the shape of an umbrella, making the plug unusable. I must have destroyed in such manner 5 or 6 of such plugs, before giving up. I did use those TE/AMP above, that someone again recommended in the bike context, and they disconnected over time, seemingly due to vibrations and weight of the wire. The 2.8mm spade connectors are straightforward to handle and work. I got the Knipex crimper for them.

As to the bike vs lab, the lab circumstances are not necessarily gentle and the connectors there may be dumped into liquid nitrogen or even helium and, in that context, the bike circumstances in the photo are actually quite moderate . However, in a lab one wants connectors designed for quick and easy reconnections and on a vehicle you want them to hold forever in spite of the vibrations. In the equipment photo collage, the holding power is provided by the locking plastic housing, not just the circular terminals.

steelbikeguy

...with the exception of the case where a quick and easy disconnect for the SON hub dynamo is desired.

I'm not aware of any connectors designed for this sort of situation... where you want a secure, reliable connection but also want to be able to just pull it apart easily. Maybe a better solution would be to rig something up with magnets? I recall someone soldering wire to a rare earth magnet and then using the magnet to make the connection to a battery. For anyone not happy with the options discussed so far, perhaps this is a path to explore.

Steve in Peoria

2_i 

An option might be some plastic tab that you press for disconnecting from the dynohub, as typical for automotive connectors. You will sure find some customers who will try to rip the connector, but then you can underscore the presence of the solution in the market. Magnet option could be good - I have such connectors for charging a headset and a headlamp and they work fine. The worry there, though, has been with the standard - if I lose the charging cable while away from my base I am cooked. To be honest, the concentric SON connector has worked well for me, holding better than Shimano that could slip off at times. On my bikes there are, though, far many more junctions than those at the dynohub. The obvious problem with the original SON connection was that the 2 tabs were too close to each other and to the hub, for fingers, and each connector had to be moved independently, That the lingering problem, scaring many customers, was finally solved at some level with that intermediate concentric connector.

steelbikeguy

regarding magnetic connectors... a quick search turns up a number of styles of them. The most generic and suitable solution might be the Dyna-Snap. Seems like it would work out fairly well as a quick disconnect for a SON hub. You'd need to solder it inline with the existing wiring.
edit: it appears to be designed specifically for bike dynamos.

Steve in Peoria

unterhausen

At $38 for one, I'm going with the Son Coax and a latte.

2_i 

One price for magnets being strong, even rare earth, is in their weight. This is concealed in the videos in the magnets being mounted on stiff wire pointing up, or on soft wire but over the fender.