Waterproof project

[lincpimp]

So my buddies and I decided we would build some scale vehicles, that we could drive anywhere. So we figured that we would waterproof all of the electronics and make them so that we could drive completely submerged.

My platform is the tamiya f350 high lift. I replaced the 3 speed tranny with a very cut down pede tranny and a reverse mounted motor. Currently running a stock silver can motor on 2s lipo thru a tamiya esc.

Used plier handle coating (pasti-dip) on the servo, lipo and esc. Put the rec in a balloon, and there you have it. I still need to pack the axles with grease, and make a electronics tray under the hood.

I will get some pics for you guys. Basically the only cusom parts are the tranny and the motor mount.

james

on the OSE online store they have a page dedicated to waterproofing electronics if you are interested

[lincpimp]

Originally Posted by azjc

james

on the OSE online store they have a page dedicated to waterproofing electronics if you are interested

I have read that, very handy info....

[TDC57]

WOW.. This sounds like a great project, especially since winter is right around the corner for most of us.. Please do post pictures Linc I'm looking forward to learning a thing or two..

Thanks Sir..

[captanabolic]

LC, prather marine cable grease is great for sealing axles cvds and such plus it is waterproof.

http://www.quicktechhobby.com/Airpla...r_products.htm

[lincpimp]

Originally Posted by TDC57

WOW.. This sounds like a great project, especially since winter is right around the corner for most of us.. Please do post pictures Linc I'm looking forward to learning a thing or two..

Thanks Sir..

I certainly will post pics. Need to make an electronics tray and finalize the wiring. Plus I am testing a few motors and gearing options to find the right combo.

Originally Posted by captanabolic

LC, prather marine cable grease is great for sealing axles cvds and such plus it is waterproof.

That gease looks similar to the stuff I use on my r/c boats. I also have some marine bearing grease in bulk somewhere... Probably use it as it is free!

[BrianG]

Probably easier to waterproof motors/ESC by getting a boat replacing the propeller with wheels.

[lincpimp]

Originally Posted by BrianG

Probably easier to waterproof motors/ESC by getting a boat replacing the propeller with wheels.

Plasti dip is your friend!! Honestly it has been very easy to do. Splash proofing would be very easy, but I want to sink the truck!!!

Lrp make waterproof escs, putting the rec in a balloon is easy, traxxas makes waterproof servos. I waterproofed my own stuff cause I am cheap.

Packing the tranny and axles with grease takes a little time. Plus I use bushings in the axles, and sealed bearings in the tranny. I will run it a bit and then take it apart and see how it does...

[TDC57]

Not to sound like a complete Nub but doesn’t your motor / ESC need air to work ?? and how do you dissipate the heat ?? Heat kills our stuff faster than anything and I'm still trying to figure it out (sorry)..

Thanks for the education..

[Arct1k]

Water would dissipate heat better than air...

I believe that to break in some brushed motors you actually run them in under water - I have no idea what that does but I'm sure I read it somewhere.

A Guide To Breaking In Your Brushed Electric Motors (Seating The Brushes)

Short version:

If you don’t want to read this lengthy post and you just want to know how to get to it, take your motor and hook it up to 1/3 to 1/2 the operating voltage for 1 to 2 hours, and it helps if you break-in the motor going the same direction as it will be turning when you attach it to your RC. Basically what this amounts to is taking 2 alkaline AA’s and hooking them in series to your motor and allowing the batteries to run dead (for 2 or 3s lipo’s, and 6 to 8 cell NiMH’s and NiCD’s). Dry break-in’s are probably the best (if you would like to see the reasoning for this see the section Types of Break-in’s).


So what is a break-in process anyway?

Looking at the pictures you can see there are brushes (they aren’t really brushes, but actually just carbon blocks), and a commutator. Basically, what we want to do is take the square shape of the brushes and wear it into the round shape of the commutator under a low-voltage, no-load situation. It should also be noted that brushless motors do not really require a break-in because they do not have brushes, and instead work on FM (frequency modulation, a type of a/c power), and brushed motors work on current regulation through voltage (current is directly correlated with voltage, if the resistance stays the same, and the voltage goes up, then the current will go up also). Also some of the high performance RC brushes (like in buggies, cars and trucks) have serrated edges, which are supposed to either reduce or completely eliminate break-in.

How does it help?

What this does is allow the brush to more fully contact the commutator over a wider area (effectively reducing motor resistance consequently increasing motor power), which reduces the amount of electricity that flows through a given piece of the brush. This in turn reduces resistance and arcing between the bushes and the commutator (as the current is transferred to the commutator over a wider contact point), which also alleviates the microscopic pitting, excessive carbon soot buildup, and excessive heat build up. All of this in turn makes the motor last longer, be more reliable, and draw current more predictably and run more efficient (see note at the end), which results in better and longer battery life.

The carbon soot is non conductive, and adds resistance to a motor, which causes it to heat more (where the resistance is, which can cause the brushes to fuse to the commutator), and loose power (because energy is being wasted in resistance (in the form of heat) before it ever even gets to the motor windings). This carbon buildup can also cause shorter flight times, and in more rare, but more serious cases can cause damage/burn-out to your ESC (3 or 4 in 1) by causing current spikes, and it could also damage batteries with the extra current in certain more unlikely situations.

The arcing in the motor over a smaller surface area, such as using a motor that has not been broken in, causes more electricity in a smaller area of the brush, which causes more heat in that particular area, which basically burns the carbon brushes creating the high resistance carbon soot, and also creates microscopic pits in the commutator and brush where the electricity arced from and to. This basically creates microscopic sand paper that also contributes to the early demise of the motor. This is a double drawback because it consumes the brushes faster, and causes pitting and carbon buildup which reduces the power of the motor, the battery life, and causes excessive heating in the motor which can fuse the brushes to the commutator.


Types of Break-in’s: Wet or Dry, Why or Why Not?

I have heard several explanations of the break-in process, and some of them involve putting the motor in water, rubbing alcohol or some other liquid, or surrounding them in ice to keep them cool. There are a few reasons to do some of these, and a few reasons not to.

First let’s start with water. The main reasons I have heard to do the break-in in water is to reduce pitting during motor arcing in the break-in, and to keep the temperature down low, and wash away the carbon buildup during break-in. I also cannot confirm this, but I have heard that water break-in’s result in a higher performance motor that doesn’t last quite as long as a dry break-in (more info to come*).

To dispel some myths about water break-in’s, no it will not short circuit, nor will it fry the motor, or over current the batteries or whatever you are using to break-in your motor. To test this for yourself take an ohm meter and place the probes in the water, and vary the distance between them. You will see that the ohm reading is quite high, though it still conducts electricity. Also it should be noted that pure water is among the best insulators on the planet. It is just the ion and particles dispersed in the water that conduct the electricity (such as lime calcium magnesium and salt).

One thing to note with a water break-in however is that it is best to use distilled water if you are going to use water to break-in your motors. The reason for this is because regular water or hard water can leave a residue of minerals on the motor parts, which could cause undesirable performance, or corrosion, and it does not conduct electricity.

Another thing to note with the water break-in is that there are small nooks and crannies in DC motors for water to stay, and over time rust and corrode the inside of the motor. These places include the spaces between the commutator, between the commutator and the armature windings, where the armature meets the shaft, in between the plates of the armature, and so on. All the water needs to be forced out somehow. Taking the motor apart is not preferred because it can change how the brushes seat, effectively reducing your break-in. A lot of people use compressed air, especially the motors with a hole in the side of the can. Obviously the smaller motors are much harder to get the water out of.

*Wet break-in’s as I have heard it originally came from slot car racing. In slot car racing they have some different parameters than in e-flight or other forms of non performance land or water based RC. The main thing is they want a hot running engine that will get a little more umph than the competition, without regards to longevity. The other thing is that most slot cars have very open motors that you can get the water out of easily.

Now to rubbing alcohol. This provides many of the same benefits as the water break-in, such as reduced motor temps, reduced to no pitting from arcing, but also adds a much better cleaning power for the commutator and the brush contacts. Alcohol also has a much higher vapor pressure, which basically means it evaporates faster and more completely than water, causing less corrosion. Alcohol is also flammable so caution needs to be taken that way, although I really doubt that anything would catch on fire with such low current and voltages.

The reason ice can be used is to keep the motor cool during break-in. Most of the time though, in my experience, if you run a motor at 1/3 it’s rated voltage with no load, it will probably not produce enough heat to really even notice, but if you run it at higher voltages it can be useful. If you would like to use this method just make sure to clean the water from the melted ice off of the motor, and out of the inside if any got in there. If you are concerned about motor temps, you can also break-in with your heat-sinks in place.

Alternately you can use a fan to cool off the motor. Try to prop up the motor so the metal isn’t resting on much (like a paper clip stand or a heat-sink or something) and put it in the air flow of the fan so in a way so that the most area you can is exposed to the moving air. This is usually an end on position to the fan, 90 degree’s to the air flow.

The Break-in Process

Basically what you want to do is take 2 new AA’s for 2 or 3s lipo’s, and 6 to 8 cell NiMH’s and NiCD’s, or 1 new AA for anything smaller. If you have two or more batteries, take them and tape them together so that the + button from one battery contacts the – plate of the other battery. Take two leads and solder them (or some other kind of electrical connection), one to each of the poles on the motors. Make sure the wires can handle the load of the motor. Most motors have a 1 ohm winding on the low end. This means on the high end they will take max 1A for every volt. So 2 AA’s would be 3A max, 1 AA would be 1.5 A max ect. Then test the leads by hooking them to the batteries. If you are picky, note which way the motor is spinning, and note which way it will spin in your RC. If they are the same go ahead and tape the leads. If they are different just swap the leads and then tape them. Let them run as long as you can wait (or until the batteries go dead), but an hour is probably the min recommended. You can also break your motors in with the heat-sinks on them if you would like them to run cooler.

....

[lincpimp]

Originally Posted by TDC57

Not to sound like a complete Nub but doesn’t your motor / ESC need air to work ?? and how do you dissipate the heat ?? Heat kills our stuff faster than anything and I'm still trying to figure it out (sorry)..

Thanks for the education..

Water will work. This will be geared so low that heat will not be an issue. The tamiya brushed escs have a heatsink plate. I just siliconed around it to seal it off, left most of it exposed. But it is an effecient esc anyways, so it will be fine. Low gearing is the real savior, this truck may do 12mph...

[TexasSP]

This will be a fun truck for sure. It's things like this that get used the most since they can literally go anywhere.

[TDC57]

Ok so it's friday night got any pictures yet???

[lincpimp]

Originally Posted by TDC57

Ok so it's friday night got any pictures yet???

Sorry, going to Disney World tomorrow for a week, so I had to work alot. I did get a test run and decided that I need a better rec cover than a balloon. So I decided to use an erevo rec box, which has proven to be waterprroof.

I also killed the titan 550 12t, so I will try the titan 23t with a larger pinion. I also removed all of the plasti dip on the esc to see if it sealed ok. No water, so I sealed it again. Steering servo still works fine, but I need some waterproof grease for the kingpins, as they are getting very gritty.

I also narrowed some tamiya vice crawler tires (from the land crusier kit) and cut them down to fit on the 1.9 wheels. They were 2,2 to start with. The stock high lift tires just get coated in mud too fast. These tires are about .5" taller overall, and do not look as scale, but should perform better. Going to add some weights in the front too.

I will have some pics when I get back and reassemble the truck. The pics will be better as I can do a "build thread) of sorts.

[TDC57]

HAVE FUN James....

It's the happiest place in the world as long as you don’t run out of money!.. LOL..

Safe travels..