U-DRONE Amethyst AUV Platform

[Oddmar]

I strip the wires, then cut a strip from an ice-cream container lid, with little notches to hold the wires separate. Then epoxy all over and ...waterproof.

If you are talking about inline bullet connectors, immerse them in a tub filled with mineral oil, plug them together submerged. Mineral oil is non-conductive, and will fill any gaps water would otherwise try to occupy. Coat the outside with 100% silicone (not in the tub).

Hopefully you realize that, no matter what BS number the chinese put on your batteries, 18650's can only be, at best, 2200ma ea. So if you are lucky, you have 12v @ 4400ma. Most 'Trustfire' or 'Ultrafire' chinese batteries are only 700ma or so, pretty crappy. Good 18650's can be bought from batteryhookup.com

[MarcoMota]

I strip the wires, then cut a strip from an ice-cream container lid, with little notches to hold the wires separate. Then epoxy all over and ...waterproof.

If you are talking about inline bullet connectors, immerse them in a tub filled with mineral oil, plug them together submerged. Mineral oil is non-conductive, and will fill any gaps water would otherwise try to occupy. Coat the outside with 100% silicone (not in the tub).

Hopefully you realize that, no matter what BS number the chinese put on your batteries, 18650's can only be, at best, 2200ma ea. So if you are lucky, you have 12v @ 4400ma. Most 'Trustfire' or 'Ultrafire' chinese batteries are only 700ma or so, pretty crappy. Good 18650's can be bought from batteryhookup.com

Thankyou for the suggestions. For the batteries you are completely right. I used batteries from an old laptop so of course I don't have all the capacity the battery had when new. Will se how it goes. If it doesn't hold a charge I will make another battery with new ones (non Chinese).

[MarcoMota]

Hi guys,

I am still on the project. I was away from home for a while so I had to pause the project.

During this time I received various I2C components that I will use for the ROV (voltage and current sensor, pressure sensor, temperature sensor, luminosity sensor, humidity sensor...).

This is the voltage and current sensor to monitor the battery status: https://www.banggood.com/CJMCU-226-INA2 ... rehouse=CN


I also purchased https://www.banggood.com/DSSERVO-DS3225 ... rehouse=UK servomotor that is waterproof but I have no idea what's the maximum depth. Has anyone tried it?

I also started to put on "paper" some possible ideas that I had to make the rudder and aileron part and for the descend ascend module. What do you think?

Notes_200821_225156_046_1.jpg (206.14 KiB) Viewed 7980 times

I am also searching for cheap resin to use to waterproof the escs and electronics that will be a+outside of the watertight enclosure, do you have any suggestion?

[Ian MacKenzie]

I'm thinking of trying this to waterproof stepper motors, using a vacuum chamber. It's not the cheapest, but it might help with heat issues.

https://www.mgchemicals.com/products/po ... tive-epoxy

[Oddmar]

I looked at your servo. From the description it has rubber seals to keep the screws from leaking, which means it is water-resistant, not really waterproof.

The reason water tries to get into our servos is because there is an empty void to fill. Fill that void with mineral oil and the water will no longer try to force it's way inside. Mineral oil is non-conductive. Disassemble the servo to locate the best spot to drill a hole through, then fill with mineral oil while immersed in a tub full of it, try and get any air bubbles out. Plug the hole with a tiny screw, making sure it does not impinge upon the internal workings.

If you have multiple servos immersed in water as i do, plumb small plastic tubing (like aquarium tubing) into the fill holes. then run all the tubing together to a reservoir, with an inner tube alongside as a pressure compensator. This makes it easy to force mineral oil into all the servos, as it leaks out past the seals it will purge the servo.
++++++++++++++++++++++++++++++++
Go to a hobby/ craft store and get some 5 or 30 minute two-part epoxy resin, mix it then add up to 50% by volume denatured alcohol to thin it, coat all electronics to waterproof. Can also be used to coat brushless motor stator windings. Or aluminum if you intend to immerse it in sea water.

[MarcoMota]

I looked at your servo. From the description it has rubber seals to keep the screws from leaking, which means it is water-resistant, not really waterproof.

The reason water tries to get into our servos is because there is an empty void to fill. Fill that void with mineral oil and the water will no longer try to force it's way inside. Mineral oil is non-conductive. Disassemble the servo to locate the best spot to drill a hole through, then fill with mineral oil while immersed in a tub full of it, try and get any air bubbles out. Plug the hole with a tiny screw, making sure it does not impinge upon the internal workings.

If you have multiple servos immersed in water as i do, plumb small plastic tubing (like aquarium tubing) into the fill holes. then run all the tubing together to a reservoir, with an inner tube alongside as a pressure compensator. This makes it easy to force mineral oil into all the servos, as it leaks out past the seals it will purge the servo.
++++++++++++++++++++++++++++++++
Go to a hobby/ craft store and get some 5 or 30 minute two-part epoxy resin, mix it then add up to 50% by volume denatured alcohol to thin it, coat all electronics to waterproof. Can also be used to coat brushless motor stator windings. Or aluminum if you intend to immerse it in sea water.

Thankyou for the help! Can you give me a brand/ name of a mineral oil you know that you would suggest me?

Is there a topic where you talk and show your use of servos?

Here are some updates...

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[fryslan76]

Beautiful designs

[MarcoMota]

Heres the stern 3D printed. Tomorrow I will use resin to waterproof the esc. The bottom file is a little gif.

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Beautiful designs

And thankyou

[MarcoMota]

Hre is the ESC waterproofed with epoxy resin...

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Heres the penetrator with all the wires used to control the servos and the motor.
The penetrator was 3D printed for testing purposes. The penetrator was closed using wax and hot glue.

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BathTub Test:
There are no major leaks.

IMG_4215.JPG (190.94 KiB) Viewed 7909 times

And here is a short video:

[Oddmar]

You went a little overboard encasing the ESC in epoxy...i just meant, thin it with denatured alcohol so it has the consistency of water, and brush it on...thin...lol.

And those wires going through the penetrators??

I hope you stripped the insulation off of the part of the wire that goes through the penetrator, before you potted it...otherwise water will find a way inside the insulation somewhere, and force it's way along between the insulation and the copper until it's past the penetrator and inside the WTC.