So far I have been using RCY connectors to connect some low power fans for a custom thingy (fursuit head, this will be relevant later (space limitations)). They have a fairly low power draw, so around 5v 0.1A.
This has worked for around a year, but as there is a lot of movement where I use it, the power leads have ripped right at the connector. It looks like this is caused by the lack of any strain relief as the connector is crimped and does not have the usual stress relief thingies, which are often seen at other stuff like psu cables, usb etc.
So I’m looking to upgrade / replace that with a different connector. I’m looking for one which has:
- stress relief against bending
- is twistable / unidirectional (so something more like a barrel jack / headphone jack)
- is small / slim (I have very limited room that’s why I initially used RCY). The size is mostly limited in thickness, not length.
- is able to carry the very low voltage and current of 5v 0.1-0.2A (so basically anything will do that)
- available in germany (most likely most things should be)
Things I have already considered:
- 5.5mm 2.5mm (/2.1mm) barrel type connector --> too thick sadly
- trying to protect the RCY plug with stuff like shrink tubes --> doesn’t work, just slips off
- thinner barrel type connectors --> can’t find a matching set of cable with plug and cable with receptacle
Rn my best bet seems to be 2.5mm headphone jacks. I do have the feeling that there might be something better out there, so that’s why I’m asking here.
Any help would be very appreciated. Thanks in advance!
Edit: Thanks for the suggestions so far, I forgot to add it to the list of the requirements that, the plug needs to be round, as one of the issues I had is that the 90° edges of the plug can get caught in the fabric. So I’m really looking for something round, so something without sharp hooks and release mechanisms.
Some 3:1 glue lined heat shrink on the backs of each connector might do the job.
The glue melts during heating and with a 3:1 ratio you get quite a bit of glue forced in around the wires as it shrinks. It then sets pretty robustly once you get down towards room temperature.
You could try shrinking maybe some 6 or 10mm heatshrink over approx 25-50mm either side of the connector (with a bit of overlap on the connector) and see how it goes. Fully shrunk it’s pretty chunky but it won’t be any bigger than the connector.
Glue lined heatshrink is sometimes called dual wall.
That could work. I need to find a way to more precisely inject the hot glue at the shrink tubing (shouldn’t be rocket science).
I actually did exactly that, but at the 5v to 12v step up module where all the 4 wire pairs leave the module. The step up module for the fans is basically rock solid and that works flawlessly.
As an alternative to hot glue, shoo goo can be thinned down with tolulene. Robrenz did a video on it but I couldn’t find it.
Check out his videos on the ultimate Kelvin connection or triaxial test leads, they are next level.
I might add, if you can, backfill the connector. I put silicone epoxy in the back of my JST connections, and adhesive lined shrink. Those connections are solid.
If you make the wire (much) longer and put the connector in a location where there is less movement will solve both the restricted space and disconnection due to movement.
Thought about that as well, but sadly that’s not possible. I do have other locations to place the connector but those are only worse and have even more movement. Rn the connector is placed against some rigid foam where there is the least amount of movement but is somewhat influenced by the powerbank pouch. The only place I can move it, is to make the cable longer and place it at the bottom of the powerbank pouch where there is only soft faux fur which experiences a lot of movement during walking and turning the head.
Smol edit: Just re-read the part about “disconnection due to movement”. –> The plug itself does stay connected. The wire at the crimped part ripped due to the stress of bending and the hard corner of the plastic casing of the RCY plug being pressed onto it. The plug itself does not get disconnected due to movement. I have only unplugged the plug in the photo to show the ripped cable better (the black wire of the negative side is ripped there).
If it’s not breaking due to movement, but only due to strain, putting the joint at the power bank seems like the logical choice. You can use cable sheathing or heat shrink where the damage currently occurs as strain relief and abrasion protection.
One other thing.
You mention a pouch. Have you considered how to deal with your power bank if it suddenly self-ignites?
About the power bank safety: The powerbank is easily accessible so I can rip it out if needed. In such a worst case scenario the first thing would be to remove the entire fursuit head first as that’s the fastest thing, before ripping out the power bank though and after removing the head when my irl head is safe is the time to think about what to do with the power bank.
The suggestion about moving the joint to the power bank: Thing is, there are 4 fans, which I connect with a custom 4x Y splitter with a 5 to 12v step up converter to the USB port of the powerbank. The fans are removable but as they are hard to position you can basically consider them semi permanently mounted. The cables then go vertically down, where the 4 connectors all converge to the custom 5v usb to 12v RCY Y-splitter step up module where they get all plugged in. That 5 to 12v step up module then get’s plugged in to the powerbank. Each fan has to have it’s own connector as it’s not possible to solder inside the suit head and that’s the only way to loop all the wires through the small cable loops to then connect them all together at the Y splitter.
In order to put the joint at the power bank, I’d have to somehow more or less attach a mount mechanism or something to the powerbank itself so that it holds the splitter module. The place where the powerbank is, is very very limited. When purchasing the power bank I specifically had to chose one which is very slim and as small as possible. So I can’t really put anything else where the powerbank is, so no mechanics to hold the cable joints there. I can basically only plug in a USB cable into the powerbank and that’s it.
Also, I can’t add anything to the powerbank that makes it harder to remove, as after each use of the fursuit head, I have to remove the powerbank to recharge it (and later add it back) and I simply can’t fiddle with any complicated mechanisms after use. It has to be really quick, so essentially it can only be as much as unplugging a usb cable.
To the heat shrinking: I have already tried that it does not work as it simply slips of the RCY plug.
(sry if the comment is a bit chaotic, wrote it at night time)
jst sm for wire to wire like this, keyed, latching, rated to 3A. Should be easily available worldwide
https://www.digikey.com/en/products/detail/sparkfun-electronics/14574/8543394
You can get them pre crimped like this if you don’t have a quality crimp tool. If you don’t go with this route. If you need to make like 200+ connections consider getting a quality crimp tool and then the crimp ends and housings, bonus there is no potential failure from solder joints (just from bad crimps since you will most likely not buy the 450€ JST WC-240 that is the official crimp tool. Tbf the engineer PA-09, which is what I use, is pretty solid once you get the hang of it and much more reasonable at ~ 30€. They don’t ratchet and they’re slower because they don’t have the wide dies but the crimp shape is very high quality, which matters. Just don’t get the ultra cheap unbranded or noname ratcheting crimpers with shit dies that cost like 10-15€ and give you bad crimps that fail 40+% of the time)
That connector does look robust, the only issue with that are the hard edges. I see now that I should’ve added that to the list of requirements (my bad). The thing with hard edges is that they can get caught in the fabric which then not only damages the fabric but also pulls on the cable / plug damaging them as well.
About getting quality gear, I fully agree with that, I’d rather spend a bit more if it means it won’t break later. If you can find / help me find some kind of round connector that would help me a lot.
Wrap with 3m friction tape? Depends on how often you need to plug unplug I guess
This was an interesting dilemma so I researched it a bit:
Apparently some people use brass/tin plated snaps. Conductive and good for low voltage. Sew in and when the suit is put on just snap them together: https://www.adafruit.com/product/1126
Some of these are used in a medical context and actually officially rated for voltage/current if you’re worried about that: https://romed.com/medical-electrical-snap-fasteners.aspx
Alternatively rosenberger makes a series of magnetic snap connectors with softer edges. Pricey though https://www.rosenberger.com/products/connectors-adaptors/magnetic-connectors/
The fans themselves don’t need to be unplugged often, only the usb plug to the powerbank has a lot of cycles.
The 3m friction tape is interesting, but tbh I think the simple 2.5mm headphone jack would be a bit easier to do and to replace in case it breaks and likely a tiny bit more reliable as I can buy it pre-done with built in stress relief against bending and it can also twist since it’s around to reduce any twisting related stress.
The snaps look interesting for me but not for conducting electricity but for potentially holding the cables tightly in place. I see the brass/tin plated snaps a bit to be risky as they could potentially short out the powerbank when the fabric flexes which I really want to avoid. While I don’t have a cheapo powerbank, so it has short protection, I’d want to avoid testing that involuntarily. (At least I’m afraid it might do that) (Note, while the current which I use is low, the powerbank can deliver the standard 5v 2A, so a short could carry 2A in the worst case)
The magnetic ones from rosenberg look interesting, but they are again quite large compared to the 2.5mm headphone jacks or even the 5.5mm 2.5mm barrel plugs.
Also smol edit: Just re-read the part about “Sew in and when the suit is put on just snap them together”. The fans are not constantly unplugged and replugged after it’s assembled. The fans are only removed when doing a deeper clean of the fursuit head as otherwise they will simply stay in all the time. When putting on the suit head / desuiting, the powerbank is the one getting plugged to the step up module.
Also here a better photo to illustrate how the entire thing is routed.
- The white pouch at the bottom is where the power bank lives. (not installed rn)
- The fans in the back are installed next and the cables get routed through the loops to the bottom of the head, where they get plugged into the step up module with the 4x RCY receptacles.
- After the fans are plugged into the step up module, that then stays in there until the next deep cleaning. So the fans will not get unplugged for a long time but they do need to have the ability to get unplugged as they can’t be pulled through the cable loops.
- When in use the step up module gets plugged in and unplugged from the powerbank
I also plan to completely remove the step up module later as I found the exact same model of fans (same series of the same manufacturer) in a 5v version with the same specs. So when replacing the plugs I won’t need the step up module anymore.
Second recommendation of the engineer PA-09, handled everything from molex microfits to tiny jst gh happily. I’ve used crappy ratcheting ones due to the volume I had to do on one project and ended up redoing half of them anyhow.
Dont cheap out on tools.
If you know anybody who 3D prints, that may offer a solution.
I’ve printed custom wire reinforcements in TPU. They are very flexible, and they will take the strain off the wire itself.
Any crimped or soldered joint is going to be a weak point. So if you can’t find something strong enough? Make it!
If you don’t know anyone who has one, you could check thingiverse.com and printables.com for a model that meets your needs, and there are plenty of print services who will make them for you.
I do have a 3d printer but, that one is currently sadly unable to print anything else than PLA (it’s a craptastic old anet a8) and I don’t know anyone at least close by who can do TPU. There is one thing I forgot to add to the original post, one additional reason I want to get something else than RCY is because of the jagged edges. They to tend to get caught in the fabric every know and then. But thanks for the advice so far, I will consider it.
Have you tried tpu? Googling says it works on the A8.
It barely prints PLA and from what I heard TPU has a bit more friction then PLA (please correct my if I’m wrong). As the frame of my anet a8 is very craptastic, because I basically got it gifted as it was broken and I needed to power glue some parts together as the crappy plastic frame was party broken. So the frame is weak and it’s also the bowden tube variant where the bowden tube heavily limits printing speed where even regular PLA printing speeds are very slow. If I up the speed from very slow even a tiny bit, then the motor feeding the bowden tube skips the filament. (Shortening the bowden tube any more isn’t possible as it’s already as short as possible) Mounting the filament motor directly to the extruder isn’t really possible as the frame is so weak that it will literally tear itself apart if any more force is put onto it.
I know that printer is basically at the point of self disassembly and I will replace it soon, but not yet.
(PS And yes I do monitor it when it prints very closely via a webcam in case it does start self disassembling) (PS PS. I did upgrade the firmware to merlin so it does have thermal runaway protection)
TPU needs less friction. It can be squished by the extruder so users frequently have to reduce tension to make it print.
Yeah, older printers’ extruders had some trouble with TPU, but TPU use similar temperature ranges to PLA.
It’s worth a shot, at least.
The other option is regular Pla. It’s flexible when thin. And I think he needs some stiffness to protect the cable from bending too much.
Is it possible to make a loop with the cable and put the connector somewhere between the crossing of the cables?
If you tie the cables together at the crossing, all the strain is on the cables, instead of on the connector.
Because as long as there is strain on the connector, all of them will eventually fail.
I’ll try making a loop with the cable through the cable holding fabric strap. Thing is that the room is very limited there, so that might fail, but I will give it a try. I will do that after replacing the plug as the loops needs some additional cable length, which isn’t there rn.
Also to note, I am still looking for a replacement of the RCY connectors, as I forgot to mention in the post, but one issue with those RCY plugs is that they have hard 90° edges, causing them to get caught in the fabric every now and then. And generally rubbing against it which isn’t good for both the plug and the fabric. So I’m looking to replace them with something with rounded corners as even when I make a loop they will still rub a bit against the fabric.
Because as long as there is strain on the connector, all of them will eventually fail.
This is key.
OP needs to secure the cable on each side of the connection, and leave a little slack for the connector.
JST! You can check out XH, PH, or SH, depending on your needs.
I used JST XH before that and that failed gloriously. The cables constantly unplugged themselves as JST XH has too little resistance against unplugging.
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