...A big shout out to Kosta for putting this up at EZILLACOMM originally...
#A: Why waterproof?
waterproofing your truck sometimes is crucial... lack of waterproofing could easily lead to a wrecked ESC, receiver or steering servo and decreased motor performance. at some cases, even the motors need waterproofing, because the vast majority of the watery stuff geting into them when submerging IS NOT clean water. water isn`t such a harmfull substance, but mud is... [especially for the brushes]. years ago, i had several motors dyno-tested before and after submerging to check performance differences, and i have to tell you that the performance may severely decrease... also [besides the brushes] even a thin coating of mud or any other substance gets on the magnets, the magnetic field can loose some of its peak [depending on the substance] and the motor performance will respectively decrease. anyway, that rule stands for brushed ones. brushless motors will get completely ruined if water gets in them due to neodynium magnet crack spots [plus neodynium is an unmachinable material]. but thats another story... [to be analysed later-on -in an article regarding brushed and brushless motor comparison and specifications]. you may not waterproof the motors [to take advantage of better cooling rate], but in this case, frequent maintenance becomes necessary...
#B: Why cooling?
Cooling is another important factor that most people forget to add into the equation. It is true that cooling is no substitute for proper gearing, but that general rule of thumb is a bit overestimated. so, whats the importance of cooling?
longer lifespan
a properly cooled motor has the potential to live more than twice towards an identical motor which works the same exact way -but without cooling. the heat produced inside a motor [while its on power], is an overall of three heat sources: the friction of the commutator with the brushes [that doesn`t apply to brushless motors], the friction produced by the bushings or bearings that support the armature, and the heat produced by the flow of electrical current through the windings [wires basically] of the rotor [or the can`s windings if it is brushless]. less heat will decrease wear on the brushes and the commutator,thus allowing for longer overall lifespan...
more performance
a critical structural and performance-wise part of most dc motors [such as those used in RC], is the magnets. the magnets create a magnetic field around the rotor, and when current flows through the rotor`s windings, a force [known as the Laplace effect] makes the rotor to spin. the strength of the magnetic field and the size of the current that flows inside the rotor`s windings are 2 major factors that assemble the motor`s performance chart. while the vast majority of hobbyists believe that the increase of current is the only way to get more power [will be analyzed in the motor article later on], it is little known to most people that the magnets loose a significant part of their peak as their temperature rises. a very good simulation link is included below: [courtesy of johnson electric corporation]
http://www.johnsonelectric.com/produ...p?ProdID=83--A
check the initial values on the performance chart: temperature [25C = ambient temperature], power/yellow curve [225Watts]. now use the temperature slider to set the motor temperature. after 5 minutes of driving, your motor`s temperature will have increased by 20C or so [depends on the style of driving, motor specs, gearing and the battery packs used]. so set the slider to 45C and re-check the specs on the performance chart. after 10 minutes of driving it isn`t uncommon to expect motor temperature ranging from 55 to 65 degrees Celcius. In a high-voltage setup with lots of weight and rotating mass involved [such as an electric monster truck] the motor temperature may climb up to 70 degrees celcius -especially at the summer season when the ambient temperature is high by itself. i will summarize the data on the following table:
Driving time [Minutes]____0-1___3-5___7-10__10-15
Temperature [Celcius]____25____45____60____70
Power [Watts]__________225___205___195___185
as you can easily distinguish, within 10minutes the power of the motor has dropped by 30watts which translates to 13.3% loss of power.
the following table is assembled particularly for the e-zilla motors and the values are combined [aka: for both motors].
Driving time [Minutes]____0-1___3-5___7-10__10-15
Temperature [Celcius]____25____45____60____70
Power [Watts]__________290___266___252___239
driving your e-zilla without forced cooling involved could drop the motors` performance by 40-61watts, which translates to a [temporary] power loss ranging from 13.7% to 21%...
i guess you now know why you should use some cooling..
#C: how do i waterproof?
waterproofing is a relatively easy but delicate process. typical ballon waterproofing is ment to burn your electronics some day. only the receiver should be swapped into a ballon, but i wouldn`t recommend that either, since there is a much more effective way to waterproof. buy a tube of 100-300gr of silicone {2$ or so} insulating compount and use it to seal and waterproof every single hole of your esc and your receiver. be sure to seal the ESCs and receivers boxes` plates [where the upper box attaches to the lowerbox], as well as the screws. do the same with the servo. allow at least 12-24hours of cure time, and carefully inspect for any spot you missed while sealing. silicone insulates water and electricity, so its safe for use almost everywhere. technicians use it in many applications. however, you should not apply silicone to the surface of the heatsinks because most of these insulating compounts insulate heat as well. there is not a specific brand or link, but any local workshop or electrics/electronics shop or even radioshack or shops selling products with paints/pipes/bathroom stuff, should stock these. you can find them practically anywhere [even at towerhobbies]. silicone is removable with a knife and it will keep water, dirt, mud and all other contaminants out of your electronics for as long as you desire. balloons will limit the airflow to the ESC`s heatsink, thus lowering its performance and effectively increase the possibilities of an esc failure. the easiest, cheapest and most effective waterproofing technique is the one you will see below {in the pictures}. everything was waterproofed: ESC, radio case & steering servo [underneath], even the motors! since e-zilla`s motors are fan-cooled [internally] it is wise to allow airflow to the endbell openings. airflow is allowed to the motor fans through fuel tubing [its very hard and rare to see mud climbing through the tubes]. the rest of the motor holes were closed and sealed with silicone as well...if however you don`t happen to dive your truck in mud [eg: you don`t like cleaning up the mess, lol], then leave the motors as they are...
Waterproofing
Linear Mode
