Speed controller

Hi, I am making a wireless remote car using a brushless motor controlled by an eletronic speed controller (ESC). But sometimes it gets close to the water and I already burned one ESC when the water shorted the 2 leads that go to the power supply. I solved that problem now isolating it very well.

But now I have another question: is there a problem if I short the 3 wires that go from the ESC to the motor? I mean, if 2 of those 3 wires get shorted (because of salty water) will it burn my ESC?

YES !

Water, more so Salt Water are a No No for any electrical connection !

You must protect everything, such as fitting the circuit boards and connectors inside a sealed plastic box and sealing any other exposed connections with silicone or similar.

If you must run in such conditions, then ensure you are using lots of fuses, so if any water does short things out, the fuse should blow and protect the device.

Thanks good to know that! I just did what you said, I covered all my esc and also the 3 connections to my brushless motor. But I still have a question: when I want to clean my brushless motor I fill a cup with water (not salt water) and turn on my motor inside of it for 10~20 seconds and it gets really clean. I never burned the ESC doing this at least 50 times in the last 3 years. Doing this in salt water would make any problem related to shorting something? I know salt destroys the motor, metal,bearings... everything. But would it also kill my ESC?

when I want to clean my brushless motor I fill a cup with water (not salt water) and turn on my motor inside of it for 10~20 seconds and it gets really clean.

Well, that's one way. If you are going to do that I recommend DI water. The more professional way would be to spray it with contact cleaner and run it for a few seconds to shake the cleaner off.

If you get water in the bearings they are going to sieze as they rust.

Never ever put a motor in water no matter how pure, it will be junk in a few weeks.

I short the 3 wires that go from the ESC to the motor? I mean, if 2 of those 3 wires get shorted (because of salty water) will it burn my ESC?

I would suspect the resistance in the salt water is significantly higher than the coils in the motor, so probably no ESC damage. After a salt water submergance, don’t energize the motor. Give it a good rinse with distilled water to dilute/remove the salt water, then soak/spray the motor with WD-40 (Water Dry #40) to displace the remaining water. The bearings may need to be relubricated.

Thanks. I usually put my motor on water to clean it and turn it on and never had any problem, my motors always last, actually I never had to replace one so far.

But I have one final question: when my arduino send a 1000 us pulse to my ESC the motor stops, when I send a value between 1001 and 2000 my motor spins. I will never put my motor on salt water when it is receing a pulse between 1001 and 2000 cause the motor is probably being energized.

BUT WHEN I am sending a 1000 us pulse the motor is stopped, so should I assume it's not receiving any power and could I put it on salty water?

My qustion looks sily but I am running an aeroboat with my brushless motor and I am afraid it may spin get upside down on water. If that happens I will stop the motor as soon as possible (with my remote control) and make arduino sending a 1000 us pulse to the ESC. Should I assume in this case my ESC will not die? My ESC is very well isolated from water, just the motor that is exposed to water.

I really would like to know the answer to this question... do you recommend any place where I can post it and get an answer?

Salty water has immediate catestrophic effects on circuit boards and no short term effects on motors. The motor can be rinsed off and will be fine. A PCB is either damaged or not. If not , if too can be rinsed off with DI water and reused. I have done it with ESCs on more than one occasion.

@raschemmel thanks man! And do you think that my ESC would burn if I put my brushless motor inside salt water (sea)? The ESC is very well protected, it will not get wet but will it be fine if only the motor gets soaked with salt water?

Thanks for your comment about PCB, I thought I could clean it after salt water but as you said, I cant.

No. Most ESCs have programmable current limit and the salty water is not going to increase the current much, if at all. If anything, it would reduce the magnetic field between the motor and the magnets inside the motor. The risk is proportional to the salt water residue left inside the motor . If it is rinsed well with DI water and then in an IPA bath after, it should be fine. I have recovered motors that were submerged while running using this method. I have also recovered some ESCs that only had minimal water exposure for a short time.

Salt water is death to all electronics.

agreed, but that excludes the motor which is only damaged by prolonged expodure. If rinsed with DI water after btief exposure thrre is no damage . Submerge a BLDC in salt water and it will run with no effect on the ESC.

seawater vs BLDC

BLDC running under water

running dc brushless motor on excessive voltage under water

I wouldn't buy one that's been abused like that!

The OP's been doing it for 3 years and never lost a motor.

But I still have a question: when I want to clean my brushless motor I fill a cup with water (not salt water) and turn on my motor inside of it for 10~20 seconds and it gets really clean. I never burned the ESC doing this at least 50 times in the last 3 years.

I really appreciate the kindness of all of you helping me with this :slight_smile: I have only a short finish question: as @raschemmel said, exposing only the brushless motor to salty water for short time will not cause any problem to the ESC. I agree with that cause I already exposed my motor running to sea water for about 2 or 3 minutes and I had no damage to my ESC.

BUT for some reason, if I expose to water the 3 wires that comes out from the ESC to normal water the ESC will not work anymore, does not matter what I try to fix. So I cant understand that: putting the motor inside the salt water cause no damage, but if the connection point (bullets) of the ESC with the motor touch the water the ESC damages and does not work anymore. Shouldnt the cases above provide the save result?

Remember: the 3 wires that comes out from the ESC goes to the motor and on the base of the motor those wires are connected to coils of the motor and I am really sure those connection are naked, there is no insulation/protection against short inside the water.

any idea?

It's a mystery. Maybe you are in the Twilight Zone.

Are sure the bullets didn't get shorted to each other ?

I can think of no electronic explanation for brushless motor ESC output leads submerged in saltwater damaging the ESC (assuming the esc is nowhere near the water) . I have not tried it yet but when I get a chance I will but do not expect any damage with the "bullets" submerged in water but not shorting to each other. If anyone else can suggest an reasonable explanation I am open to it but I can tell you the saltwater is not likely to conduct enough current to cause shorting between leads.

@raschemmel I would really appreciate your confirmation of my tests cause maybe other people could provide a google explanation. But sir, do you agree that shorting the 3 bullets (touching them together) would damage the ESC? Or do you think that even touching them they will not damage the ESC?

your expalantion of salty water not being able to conduct so much current to damage the ESC may be a good explanation and it may be the good answer! I hope someone smart can check th conductivity of the water and check if the wires in a distance of about 5mm would cause a significant short.