Heat soak and motor temperature observations

[siberianhusky]

Set up the telemetry in my boat just because I had it, Was very interesting monitoring motor temps.
When I was running temps were 86-87 F, by the time I'd get the boat out of the water and onto the stand temps had risen by 20 more degrees, on the stand the temps maxed out at 140 no more than 4 minutes after the run.
ESC and batteries were coming in a little above ambient air temps.
By the time you get the hatch untaped and check temps the had risen over 20 degrees every run.
Johns boat was ending up with temps about the same as mine by the time we were able to check with the IR temp gun.
3 minute runs voltages on the packs was 3.75-3.87 at the end of 3 minutes running, 5000mah 20c Flightmaxes.
The interesting thing was the HK2300kv 3650 motor pulled less out of the packs than a blue can SV motor, both were running x440/3 stock S/B'd props. Same hulls and same batteries almost the same hardware.
John has a hifei 90 I have a 120 esc both programmed the same.
Hot melt glued the temp probe on the end of the motor about where we point the temp gun.
Was fun doing a side by side test of the two motors in pretty much equal boats.
No idea who was faster, although I did blow over 3 times, once upside down. Was great on glass smooth water a little too loose for race water.
Oh ya the water pump went on my truck 2 blocks from home, have a spare in the shop already, 3.77$ for two gaskets.
Guess what I'm going out to do! Don't mind actually I like working on older trucks, nice when you open the hood and can actually see the engine, LOL I can sit on the fender and put my feet on the frame next to the engine while working on it!

[johnmaclean]

Great afternoon. Batteries are on charge out on the patio. Should take the remainder of the evening. We decided to head out on the lake tomorrow morning rather than anchoring out tonight. Looks like another stellar day, weather wise. I will take both sv27's along and see if I can't persuade my wife to run the orange one. She loves the mini vees and is a lot more nervous about the supervee.

Glad we had the same ESC's and were able to get the USB progarmmer and laptop togehter.

Sorry to hear about your water pump issues. Hope you were able to make it home ok.

[Alexgar]

I have 6 boats to take out tomm got my hk order escs and fitted with wc block can't wait dumped my renegade and she's back up by far my favorite followed by my nimble df29 can't wait start a new job tues and my wife next wend what a great week it turning out to be as my wires been laid off for 2 mnths and that frees up a little hobby money yeah!!!

[siberianhusky]

It's an easy fix on a good ol' gmc, took longer to drain the rad than it did to change out the pump.
She'll be loving it after a pack or two running time.
Still no word on IW if the guy is going to sell me that nitro motor.
Tracking still says in transit on my batts and parts.
Going to order some more connectors, I got the last ones at Lakefield Hobby. I'll try Hobbyhobby.com Out of Toronto, took about 2 days to arrive last time I ordered stuff from them.
We'll put out the word early and see who we can get out.

[Alexgar]

What kind of motor are you looking for I have a 46 and a 19 i can part with if you need them pm me

[siberianhusky]

Thanks but lookin' for a .12 If the run that class this fall I may go run my JAE, doubt they'd run mono.

[Alexgar]

Cool just some things I wanted to get rid of haven't touched nitro in a year or two

[siberianhusky]

I'm only interested in the .12's now, gutted my .21 mono for an electric conversion.
Cheap engines, I still get to tune carbs, get great mileage out of a gallon of fuel. And I love it when your nose burns and eyes water from the exhaust fumes running 50+% nitro.

[m4a1usr]

Set up the telemetry in my boat just because I had it, Was very interesting monitoring motor temps.
When I was running temps were 86-87 F, by the time I'd get the boat out of the water and onto the stand temps had risen by 20 more degrees, on the stand the temps maxed out at 140 no more than 4 minutes after the run.
ESC and batteries were coming in a little above ambient air temps.
By the time you get the hatch untaped and check temps the had risen over 20 degrees every run.
Johns boat was ending up with temps about the same as mine by the time we were able to check with the IR temp gun.

Sounds like you got some good information confirming what I have been preaching for years. A motors true temperature is not on the exterior, but deep inside like at the rotor and steel laminations in the stator. It takes awhile for those temps to conduct to the exterior. Great job. Now you see why I dont put a lot of faith in water jackets. Yes they do conduct shell or skin temperatures but the true motor temp is never going to be on the outside. A first year science student understands basic thermodynamics. The shell is not where the heat is generated. But on a side note, boy can I relate to the old chevys. The part about room to work. Man those days are long gone and sorley missed. Almost brings a tear to the ole eyes.

John

[JimClark]

Precisely why I put computer fan on the motor immediately after opening up the boat

[Fluid]

...Now you see why I dont put a lot of faith in water jackets. Yes they do conduct shell or skin temperatures but the true motor temp is never going to be on the outside. A first year science student understands basic thermodynamics. eyes.The shell is not where the heat is generated.

Interesting observation. I doubt you meant to imply that water jackets have no use in FE boats. A first year science student knows that heat energy moves from high temp to lower temp. With the heat generated inside the motor (interesting observation) the water jacket will draw heat from the motor, reducing the heat transfered to internal motor parts - in other words the motor stays cooler everywhere including the magnets. Without a water jacket for cooling all you have is internal air - which is not nearly as efficient as is circulating fresh unheated water directly in contract with the motor can.

Blowing air through holes in the can would be great at removing heat from the motor's internals, but only on motors with holes in their endbells. Even then, with the tight tolerances between rotor and stator (and between the windings within the stator) there isn't much room for air circulation through the motor. This potential effectiveness assumes relatively cool air, which is not present for very long in hulls with limited internal air volume - but with lots of heat sources (motor, ESC and packs all pumping heat into the internal air). This is made worse by filling extra internal volume with floatation. I certainly agree that water cooling can only go so far in removing heat, that many boaters over-estimate its effectiveness, and that it is no the cure for a setup which generates too much heat too fast. But it is an essential component in FE boats which require more run time than a couples passes.



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[m4a1usr]

Interesting observation. I doubt you meant to imply that water jackets have no use in FE boats. A first year science student knows that heat energy moves from high temp to lower temp. With the heat generated inside the motor (interesting observation) the water jacket will draw heat from the motor, reducing the heat transfered to internal motor parts - in other words the motor stays cooler everywhere including the magnets. Without a water jacket for cooling all you have is internal air - which is not nearly as efficient as is circulating fresh unheated water directly in contract with the motor can.

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No way would I imply water cooling as no useful purpose but I do not believe its very effective. And the reasons are very simple. Since most of the mass of our brushelss motors are steel, and steel is a very poor thermal conductor (the copper and aluminum are the real ones doing the job) the heat transferred is small. While the force creating the heat is much, much larger. You cannot remove it from the stator as fast as its increasing. The rates are drastically different. Maybe immersing the motor in liquid would work but having a shell cooler has little effect. Look how thick (cross sectional area of the stator). Now onto the rotor. Its getting hot due to its approximate location. And its insulated from conductance by an air gap. Air is one of the best insulators, not conductors. But the only way to honestly know is to do a accurate test. One would have to have a braking dyno, a calitbrated power source, an IR gun to measure the rotor temp, thermocouples attached to the stator and shell. Then measure the delta T of the water in and out. Not to mention you need a flow meter for GPM and a multi channel data logger for all of the data points. That would be cool.

With all of that you could accurately state how much heat you could pull out. But I dont need a lab enviornment to tell me a 1/8" water line with 65 degree water entering into a chamber with a flow rate of something like 16 to 20 ounces per minute is capable of pulling out any serious amount of btus. The math is all one sided.

Heck an optimum setup motor with 93% eff and pulling 100 amps on 6S is going to have 155 watts of waste heat. That doesnt count the other regions of the power band during its operation where the ineff is going to be something like 20% or more! And I doubt any of us are operating at 93% motor eff. My only point about water cooling is what we use and how we use it is pretty much ineffective. Doesnt mean its useless. But you can get better results by properly selecting the motor to the load, then counting on secondary methods. I'm not arguing with you Jay. I'm just doubtfull as to the benefit that alot of folks seem to assume. Who would put an air conditioner in their home that could only drop the temp by a couple degrees? Thats what I'm thinking.

John

[siberianhusky]

Thinking fan for some motors/mounts and a closed loop bench top liquid cooling system, I'll try a gallon bottle of lake water with a windshield pump to keep some water circulating after runs. There is a chance I have one of those in the shop as well (packrat!)
Don't know how much it will help but won't know until I try while monitoring the temps.
I'll get back to work on that super conducting esc and motor, got distracted by a piece of tinfoil caught in the ac vent. Shiny!
That truck will hit half a million km this year, still running strong! As a stone mason I work my trucks hard. All in the maintenance. It does need a new box though, the bottom is so dented in it's sprung the side seams.

[LuckyDuc]

I fill a large syringe with cold water before my heats and flush the cooling system right after running. Mitigating the heat soak will prolong your motor's life. I've been running the same UL-1 motor for almost 2 years now.

I've seen a gravity feed setup used too. It was a 2 liter bottle upside down with fuel tubing and a shut off valve.

[Steven Vaccaro]

Im not into all the math, but try using a motor without a water jacket. I think you already know the results. :-)