Waterproof connectors - any suggestions?


#1

Hi,

I'm just getting started with an U-ROV this days.

I would like to build the ROV in Modules like "light-module", "battery-module", "motor-module" and so on.

My question do you know a cheap and reliable watertight connector solution that works?

Has anybody already checked these out:

http://www.reichelt.de/Buccaneer-Serie-400/PX0410-04P-4550/3/index.html?;ACTION=3;LA=5;ARTICLE=124433;GROUPID=5571;artnr=PX0410%2F04P%2F4550;SID=10ULRqSX8AAAIAADc9G@s792ad461adefcb59c9baa19687331156

http://www.reichelt.de/Buccaneer-Serie-400/PX0412-04S/3/index.html?;ACTION=3;LA=5;ARTICLE=124462;GROUPID=5571;artnr=PX0412%2F04S;SID=10ULRqSX8AAAIAADc9G@s792ad461adefcb59c9baa19687331156

They are only specified up to 10m - but probably the will resist even higher pressure...

Thanks

-Tobi


#2

I used that type of connectors, and they are not very good.
I used them on the previous version of my homebuilt ROV and was always water inside the EPOD.

Jose


#3

Ah thanks. Good to know. What did you use instead?

- Tobi


#4

I just fill the box with the electronics with epoxy resin.

I can't remember the type but was like rubber. So if you have a problem you can take the resin, repair the electronics and fill again.

The homebuiltrovs site have some good ideas too without using resin.


#5

Interesting. Did you identify the problem and where/how the leak was happening?

We’ve had similar problems with connectors, and are looking hard for a better solution.


#6

Hi Tobi,

Letztes Wochenende habe ich angefangen eine Funkboje (Mini Wlan Router) für mein ROV zu bauen.

Dafür verwende ich ebenfalls Bulgin Stecker (PX0834/B).

Weil ich mir nicht ganz sicher war ob die Stecker 100%ig dicht sind habe ich den Hohlraum im Steckergehäuse vor dem Verschrauben der Dichtungen mit 2K Kleber Versiegelt.

Grüße Holger


#7

i think the cheapes commercial used connectors are Seacon RM series (http://seaconworldwide.com/products/electrical-dry-mate/rm-rubber-molded/) and LEMO.

the prices vary alot with amount of pins, amp-ratings etc

here are some ball-park numbers: http://www.amronintl.com/seacon.html


#8

I've extensively used subconn connectors. They're somewhat expensive, but I've never had a problem with them. Think like $50-150 each.

The buccaneer connectors i've seen go deeper then 10 meters, but it isn't really advised. that type of connector may do better if the connector is also sealed with epoxy at the bulkhead contact.

http://www.vpi.us/cable-glands.html the waterproof cable glands work fairly well, and are cheap. they're not really a connector though.


#9

I to have been looking into Seacon connectors and the price quote I got was a bit expensive for this type of project. Maybe better prices can be had if we bought on volume. Here is the prices I got here in Canada. This is for a Male & Female connector.

MCBH4M-Brass $63.68 each

MCIL4F $38.10 each

MCDLSF $8.05 each


#10

these prices are not that bad, a similar subconn costs alot more here in Norway.

These are connectors that are rated for several thousand feet of waterdepth, so yes they cost quite some money for a hobby rov maker. but you will also have these connectors for several years without problems.

in addition to the connector and cable you need 3M 2131 scotchcast(or other PUR(polyurethan) mould) to mould the MCIL pigtail cable to your umbilical or other cables. the outersheet of the cable youre moulding against, must also be in a rubber material. PUR is a good outersheet material for moulding.


#11

Hi Guys,

look how they have solved it here. I like the idea!

www.rov.cc

-Tobi


#12

Tobi,
Are you referring to these DIY connectors?
http://www.rov.cc/index.php?option=com_content&view=article&id=56:durchfuehrungen&catid=34:mechanik&Itemid=56

Interesting...

I already worry that the epoxy portions of the ROV are going to be really easy for people to mess up (with pretty catastrophic results). I think making the connecters something that need to be built would increase the failure potential. This is an awesome resource, though! Creating our own is intriguing.


#13

So a couple of days ago I glorped some silicone grease into an RJ45 connector, then measured the contact resistance when a plug had been inserted. I didn't notice any change in resistance due to the addition of the grease. I had been wondering whether Subconn/Seacon connectors have anything magical in them that allows you to grease the contacts, but it appears that any sort of sliding contact handles that situation.

After I couldn't come up with a good way to mount an RJ45 socket in a way that would be easy to waterproof, my thoughts turned to how to make this connection as simple as possible, and the best I came up with were banana jacks. For instance, Pomona makes a simple mini-banana jack:

http://www.pomonaelectronics.com/pdf/d3277_1_02.pdf

It seems like you could press-fit this into a hole in the plastic shell, then add some potting as necessary to make sure the interface is waterproof. Mouser sells these for a buck:

http://www.mouser.com/Search/Refine.aspx?N=4292986704&Keyword=3277

Pomona has a mating gold-plated plug for this:

http://www.pomonaelectronics.com/pdf/d3276-4513_103.pdf76-4513_103.pdf

So the one question I have about these is whether there's enough gap between the tip of the plug and the opening on the jack to force out excess water and grease when you go to mate the two. More experimentation is in order I guess....

-Walt


#14

What about -not- making the jack waterproof? Why not attach a female jack to a small length of cable (for example, 8 inches), at the other end of short cable do your waterproofing, potting, cable gland, etc. at the hull of the ROV. A bit of potting on the individual wires, slightly before the male jack and after the female jack (close to ROV) could eliminate “water jacket” effect. Add a strain relief at the male to female jack connection. After all that, you get a side benefit of removable tether.


#15

So over the holidays I ordered some mini-banana jacks and plugs from Mouser. Tonight I filled one of the jacks with water, put a little silicone grease on the plug, and had no problem inserting it into the jack. Contact resistance was unmeasurable.

I think this might be a viable option for electrically attaching the tether to the ROV (it will need a strain relief, of course, for the mechanical attachment). I'll bring some of the plugs/jacks to Saturday's build day to see how the jacks might fit onto the ROV itself.


#16

Seems like a decent idea. The question I have about any of these "wire through potting" schemes is how well can you actually seal against water water wicking between the insulation and the wire, especially as one moves to greater depths? (I think this is what you are calling the "water jacket" effect.)

Perhaps this idea would work best if you actually stripped away some of the insulation on the wires where they're running through the potting, so the potting material would be in direct contact with the wire. If the wire for this short length was solid (as opposed to stranded) you should get a good seal.


#17

Great!! Looking forward to seeing it.


#18

Yea, the hosing effect is a serious concern, especially with the twisted pair.

I've done exactly what you suggest: strip away some of the insulation in the potted pass through just in case.


#19

A user on the homebuildrovs forum has also used banana connectors: http://www.homebuiltrovs.com/rovforum/viewtopic.php?f=18&t=815&start=30

The subconn/seaconn needs lubrication because of the friction of rubber agains rubber, but also to give the rubber a better sealing.

The sealing principle on the connectors are 2-3 small grooves in rubber on the pin, and the inside of the female plug has an smaller diameter where the pin has grooves - thus making a principle of 2-3 oring seals per connector pin(!)

The mc series has 2 groves, and the larger ones has 3.


#20

Hi Guys,

I'm all very new to OpenROV so please excuse any ignorance on my part.

is there any merit in having a lazer transmitter/receiver as the connection, thereby reduce the risk of a through hull connection?

See 'A simple laser communicator'.

Regards

James