Topic: Electrical connections in water (Read 6686 times)

Davy1 · « **on:** November 26, 2013, 09:19:39 am »

Any one any thoughts or ideas on how to make in-water electrical connections without the trouble and expense of waterproof connectors?

- higher current connections (battery etc.) pose no particular problem. Well vaselined connections, brass nuts and bolts through bulkheads all seem to work well and reliably.

- signal connections (servos etc) - not so easy to make reliable connections. Anyone seen, heard of or used optoelectronics (LEDs, optocouplers etc.) or any other technology?

David

html · « **Reply #1 on:** November 26, 2013, 12:02:11 pm »

How about amalgamating insulation tape, moulds well around items and it sticks to itself so would prevent any water ingress to joints

Brian

Davy1 · « **Reply #2 on:** November 26, 2013, 03:57:51 pm »

Thanks for your suggestion. Amalgamating tape is excellent stuff.

The problem with anything like that (and I include "waterproof" plugs) is that you don't know if there is any water in the joint which then causes damage and corrosion over the long term. (days and weeks).

But thanks again.

David

McGherkin · « **Reply #3 on:** November 26, 2013, 06:53:41 pm »

I'll have to chat to an electrician friend, but if I recall correctly, in work they epoxy joins and connections, then heat shrink, then amalgamating tape.

If it's good enough for the big submarines, it's probably good enough for the little ones too

salmon · « **Reply #4 on:** November 26, 2013, 07:00:10 pm »

David,
I know of a man in Canada who played with optoelectronics. It can work, but as I understood it (and this guy is beyond brilliant so much went over my head) the issue comes down to waterproofing also. Mud, silt, algae, and what nots would/could interfere with signal. Unless it is sealed. There were others parts to the discussion about refraction and something with signal interference that left me knowing it can be done, but thinking is it necessary. Fun for sure.

Peace,
Tom

Subculture · « **Reply #5 on:** November 26, 2013, 09:35:53 pm »

Unless the function has to be super quick, how about using sound instead of light?

david48 · « **Reply #6 on:** November 27, 2013, 08:29:15 am »

I might not understand the question ,but I have been using insulation varnish on the mast wireing of my build ,to get it off it needs a good hard sand/scrape to get it off to do any solder work .
David

Davy1 · « **Reply #7 on:** November 27, 2013, 11:21:13 am »

Thanks for all the suggestions so far.

The full size submarine approach - epoxy+shrink fit +amalgamating tape - is wonderfully belt and braces and sounds good for long term immersion.

The problems with optoelectronics - biological fouling etc. - is a problem for long term use, certainly.

Model submarine applications seem a little different in that the connection is "dunked" briefly and then allowed to dry out.

Sound - too bulky and complicated, certainly for a single signal channel.

The insulation varnish (presumably see through?) seems an interesting one in that it will dry out and you can visually check for corrosion etc.

Many thanks for the help and suggestions so far.

David

david48 · « **Reply #8 on:** November 27, 2013, 01:40:49 pm »

Yes it is clear .There are different types have a look on RS components website the one I use is the brush on sort
David

Davy1 · « **Reply #9 on:** November 28, 2013, 05:29:36 pm »

Thanks. So something like RS part No. 569-313.

That's an aerosol spray on acrylic conformal coating as used on Printed Circuit Boards??

I'd never thought of that kind of coating for wiring.

Thank you!

David

Davy1 · « **Reply #10 on:** January 03, 2014, 10:27:44 am »

unbuiltnautilus · « **Reply #11 on:** January 03, 2014, 10:38:51 am »

Tell us more, we need to know!

Davy1 · « **Reply #12 on:** January 03, 2014, 10:59:13 am »

Sorry I seem to be having broadband and phone connection problems - the gale last night perhaps.
Assuming you can see the photo, which shows the test of conformal lacquer. One half of the brass strip sprayed once (guess which) then immersed in pond water for 12 hours with 12v applied.

Looks very promising for protection of brass bolts, lead acid terminals etc. Second coat would be worthwhile, perhaps.

Thanks for the useful tip , David. (And a Happy New Year)

David

Rodgearing · « **Reply #13 on:** April 08, 2014, 12:06:21 pm »

I have noticed that where the bigger gel filled battery's are used that they are outside the WTC so I take it its a matter of making the contacts void of water by putting the cable on the terminals and putting something over the contacts. (Obvious statement I guess) I think my point is what is the general consensus as to what we use. I would perhaps put silicon sealant over the terminals the one that goes really hard.
Fred

unbuiltnautilus · « **Reply #14 on:** April 08, 2014, 01:10:35 pm »

I would use epoxy resin rather than silicone sealant. Placing a coffer dam around the soldered terminals first ( last time I did it, i used Blu Tac for the dam. I am sure there are tidier ways of doing it, I was in a rush! ). Silicone Sealant has a tendency not to stick at that vital point, or fail later under stress, so I save it for any above water, but exposed joints. Solder, silicone, heatshrink, job done.

david48 · « **Reply #15 on:** April 08, 2014, 11:21:22 pm »

Ifound this stuff in a TLC Direct catalog ,it's called Wiska Magic Gel IP 68
The web site is www.tlc-direct.co.uk Part no. WK MF170 170grams £8.70
David

essex2visuvesi · « **Reply #16 on:** April 09, 2014, 07:36:32 am »

http://www.plastidip.co.uk/eStore/index.cfm?Plastidip_Liquid_Electrical_Tape_-118ml&stage=3&colour=Black,Red&pid=PDL-0019

We have used this successfully on electrical connections on exposed tractor wiring and it works a treat

derekwarner · « **Reply #17 on:** April 09, 2014, 12:31:59 pm »

If God wanted battery terminals to be placed under water......he would have given Noah the instructions!

...IP68 may sound to be acceptable [protection against submersion] ..........but don't touch it.......don't consider it........buy yourself a cigarette lighter or a LOTTO ticket.......

.....Derek

Davy1 · « **Reply #18 on:** April 10, 2014, 09:48:12 am »

12 volt sealed lead acid batteries are just fine in fresh water. I have been using them very successfully for years.

In the past I've just put a smear of Vaseline on them and used a standard car type spade connector (not sealed or anything. They work very reliably and the only thing you will notice is that the positive terminal goes a bit green. The battery is therefore very easy to connect and disconnect (no need for switches etc) all of which "enhance your pond side experience!" (i.e prevent you being driven mad by sailing model submarines - they are tricky enough!)

As a result of this thread, I started, I've learned a lot from you kind colleagues and I have started spraying the terminals with lacquer (conformal acrylic lacquer as used on printed circuit boards). I still smear a little Vaseline on them for old times sake!

I have just been looking at a new battery that has had this treatment and has been used for about 4 sailings in my Type XXI since this March. The tin coating is still on both terminals. So lacquer (+ Vaseline ) looks about right.

David

Davy1 · « **Reply #19 on:** July 05, 2014, 12:50:24 pm »

Just an update on this one and some trials I made on transmitting servo signals through clear plastic and even water.

It's a very simple setup. The sender unit (connected to the receiver) was just an Infrared LED The receiver unit (connected to the servo) was a photodiode

The early trials were surprisingly successful with the signal being happily beamed through several mm of plastic or even water.

If you used a separate 5v supply at the receiver end then that is just one wire to transmit a servo signal.

More details over on the AMS Forum.

David

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Author Topic: Electrical connections in water (Read 6686 times)