Brushless motors self switch on in salt water harbour

[lostcaggy]

Hi

I tested my ROV in local harbour today, using brushless motors controlled by an Arduino, out of
water all working fine. As soon as I put the ROV in the harbour, 3 of the motors switched on to
full power I sent signal to turn them off but that didn't work. Does anyone have any ideas at to
how to fix this.

Thanks
Martin

[sthone]

What are you using for motor controllers and are there any exposed connections from the motors?

-Steve

[AHarris]

As Steve has mentioned, you could have an exposed wire.
Although water doesn't conduct electricity very well, with salt in it acting like an electrolyte you can easily create a short circuit.
This could be turning on your motor, when it happens do you see lots of tiny bubbles rising to the surface?

If so then it is an exposed wire and you are creating hydrogen and oxygen (in this case chlorine gas instead due to the salt and oxygen).

[lostcaggy]

What the best way to quote the winding wires and what do you suggest with.
Thanks
Martin

[AHarris]

Sorry if I have misread your message, do you mean "How do you coat your wires and what with?"

If so, then I would suggest concealing all your exposed connection in a Hobby Box as Steve has done with many of his projects and then filling it with wax.
This shall act as a junction box and all wires that have been soldered are protected form water but make sure you put electrical tape on them to stop them touching each other.

Here is a link to Homebuiltrovs.com page on this matter:
http://homebuiltrovs.com/seafoxretrofitcontrol.html