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  1. #1
    RC Racer
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    UDR cooling fans

    Was looking for ways to cool down the UDR and I stumbled upon these 40mm x 40mm 3D printer fans rated up to 24v.

    https://www.amazon.com/dp/B088665SKK/ref=emc_b_5_t

    I live in the desert southwest area of the US. I need all the cooling I can get especially now during summer.
    Haven't ran my UDR yet so I do not have a baseline on temperature ranges. But we have been averaging 110F ambient temperature here and using my TRX6 as a reference, my motor gets up to 150F+ and that's just crawling.

    I just want to make sure my UDR motor and drivetrain stays cool. I will be slowly upgrading to aluminum parts to help dissipate the heat. I am also not an electrician, and only have basic knowledge on how electricity works. My questions are:

    -Will these fans affect my runtime?
    -Will the batteries be able to handle the discharge rate with the fans?
    -If I hook it up directly to the ESC, is the ESC good enough to handle the amp draw when I do high speed runs/lights all at highbeam/fans running?
    -If I hook it up to the receiver, what is the voltage rating of the receiver? and is it regulated constant at that voltage even with 4s or 6s batteries?

    I may just be overthinking because I'm just excited to tinker with my new UDR, but any input or better ways to cool her down is appreciated. Thanks!

  2. #2
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    Also found the HR brand, and GPM fans that attach to the back of the motor. Any issues with it hitting the driveshaft? The clearance is really tight.

    And lastly, this: unbranded from China and mounts on the side of the motor. sorry for the long link.

    https://www.ebay.com/itm/42MM-Waterp...6a88%7Ciid%3A1

  3. #3
    RC Qualifier RCWilly's Avatar
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    The fans will not affect the run time (even if it does, it is not noticeable). The batteries will be able to handle the discharge rate with the fans (the fans do not require much power).

    For powering the fans, I think it is overall cleaner and easier to hook it up to the receiver (voltage rating of the receiver is 6 V, and it always stays at 6V, no matter 4s or 6s).

    One thing I think you should consider is the mounting location or the mounting position of the fan on the motor, since there is not a lot of room inside the chassis. Also, the motor is covered with a skid plate, so even if it could be mounted inside, it would just be a closed circuit airflow (by closed circuit, I mean the same air circulates in the same area) and no cool air would be able to access the motor.

    The only part of the motor that is not covered is the base of the can, so that may be the best place to place the fan. Here's a pic that I have found:



    Another option that makes the motor run cooler is to gear it down.
    Everyday's a gift, thus now is called the present.

  4. #4
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    thanks for the input! I do like a clean install so I will go with the receiver route. And yea that's the one I saw at HR website. I dont have exact measurements but just by looking at it and the space in the chassis, it seems like one side of the fan and aluminum base will hit the driveshaft. But then again maybe not, as HR is known for good fitment and quality.

  5. #5
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    Quote Originally Posted by Unstudded_6.0 View Post
    Was looking for ways to cool down the UDR and I stumbled upon these 40mm x 40mm 3D printer fans rated up to 24v.

    https://www.amazon.com/dp/B088665SKK/ref=emc_b_5_t

    I live in the desert southwest area of the US. I need all the cooling I can get especially now during summer.
    Haven't ran my UDR yet so I do not have a baseline on temperature ranges. But we have been averaging 110F ambient temperature here and using my TRX6 as a reference, my motor gets up to 150F+ and that's just crawling.

    I just want to make sure my UDR motor and drivetrain stays cool. I will be slowly upgrading to aluminum parts to help dissipate the heat. I am also not an electrician, and only have basic knowledge on how electricity works. My questions are:

    -Will these fans affect my runtime?
    -Will the batteries be able to handle the discharge rate with the fans?
    -If I hook it up directly to the ESC, is the ESC good enough to handle the amp draw when I do high speed runs/lights all at highbeam/fans running?
    -If I hook it up to the receiver, what is the voltage rating of the receiver? and is it regulated constant at that voltage even with 4s or 6s batteries?

    I may just be overthinking because I'm just excited to tinker with my new UDR, but any input or better ways to cool her down is appreciated. Thanks!
    I also live in the desert Southwest and triple digit temps makes me hide my models. Me - no. As a former armed forces brat I lived in two desert regions. Doesn’t even bother me at 62. But my babies will stay safe. Even if one of them is desert racer. I can hear them saying “I’m melting...”


    Sent from my iPhone using Tapatalk Pro

  6. #6
    RC Racer
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    I got the Hot Racing rear fan on order and also the side mounted fan! Triple digits will not stop me!

    Sent from my SM-G975U using Tapatalk

  7. #7
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    Quote Originally Posted by Unstudded_6.0 View Post
    I got the Hot Racing rear fan on order and also the side mounted fan! Triple digits will not stop me!

    Sent from my SM-G975U using Tapatalk



    Sent from my iPhone using Tapatalk Pro

  8. #8
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    Just a quick little update.

    I Installed a temp sensor to monitor my motor temp. So now I can monitor both ESC and motor temp using telemetry.
    Ambient temperature when I conducted my session was about 100F using 2x 7600mah 2s Traxxas battery.
    After about 25 mins of non-stop drifting in the desert, a few full sends, ESC temp was appx 130F and Motor temp was between 150-160F
    That's actually good news! My TRX6 runs hotter with the AXE 550 system while crawling - using a 3s battery.
    We'll see if those 2 fans I ordered will make a difference.

  9. #9
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    Had another 30 minute session. Same parameters.
    But this time I was harder on the truck. Lots of full sends! Just before LVC triggered, I looked at my temps and ESC is constant 130F, motor was hitting 180F. That's about my limit. I do not want motor temps hotter than that. I read from other threads that 170F is the sweet spot for brushless motors. I need a duct system that sucks in air from the front to cool the motor lol.

    Sent from my SM-G975U using Tapatalk

  10. #10
    RC Racer
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    Installed the Hot Racing rear mounted fan! Another day, another 30-minute session, 4th time my UDR has been ran.
    Same parameters, appx 100F, 4s batteries, stock gearing etc.
    ESC was averaging 130F, and my motor temps was about high 160s and low 170s. And I was pushing my truck hard. I even rolled her over on loose dirt, not once but twice! First time I've rolled over this bad boy. And also lost a back caliper, and half of the carrier hub. I don't know how that happened lol. So I was really beating her up.
    Glad to see the fan helped, a differece of appx 10+ degrees.
    It's rated for 12v but it's just plugged in to my receiver so it's only working at half it's capacity.
    Still waiting on the side mounted fan from China, I'm also planning some sort of duct work that would suck in cool clean air from the front.

  11. #11
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    i saw a thread onhere from a guy who changed the fake fans to real ones

    found it

    https://forums.traxxas.com/showthrea...R-cooling-fans
    Last edited by packaert; 08-04-2020 at 01:20 PM.

  12. #12
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    Quote Originally Posted by packaert View Post
    i saw a thread onhere from a guy who changed the fake fans to real ones

    found it

    https://forums.traxxas.com/showthrea...R-cooling-fans
    Thank you! that's definitely a cool setup! gonna figure out a way to wire the BEC on my stock ESC to get the full 12v powr of the fans. I am bad with electronics so any input would be great l
    ol. And I want my intake to come from the front, for cleaner/no dust air. My rear mounted fan current draws dirty air from the back, but it works, just gets the heatsink all dusty lol.

    And I forgot to mention this in my earlier posts, the Hot Racing Rear mount heatsink and fan have no clearance issues. It fits perfectly and will not hit the driveshaft unlike it's GPM counterparts.
    Last edited by Unstudded_6.0; 08-04-2020 at 02:19 PM.

  13. #13
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    Another update.
    Ambient Temp 106F, 4s battery

    Side mounted fan arrived, barely enough room on the side to install it but it fits lol. Replaced the rear mount and the side mounted fan with 40mm fans from Team Corally. Rated for 6v-8.4 volts with a max rpm of 22k @ 8.4v. These fans really push air!

    https://corally.com/Variateurs/Venti...BEC-connector/

    Average ESC temps was about 145F, it was really hot outside. Drove the truck with moderate - heavy throttle. And did some full-sends with whoops and jumps. Motor temps with the 2 fans installed stay consistent at appx 160F. I'm happy with the numbers. I just hope these fans will last me a long time. With cooler motor temps, I have actually noticed almost 10 mins increase in my run time using 2x 7600mah 2s batteries. I even brought extra batteries just in case but did not need to use them.
    The rear mount fan actually stays clean and does not suck in small rocks. I placed small mesh cloth in the intake side to protect it from larger debris but the fan ended up just eating the mesh. It was gone after my session haha.

    My only concern is, with 2 fans, both connected in a Y harness to CH1 in my receiver, will it possibly fry my receiver? I am not sure of the amp draws. And I've been looking everywhere what voltage/amps the stock receiver can take. All I know is it puts out 6volts. Thank you

  14. #14
    RC Qualifier RCWilly's Avatar
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    Pretty sure the stock receiver can only take 6V. Also, I think it's the ESC's job for the amp draw, so the receiver should be fine.
    Everyday's a gift, thus now is called the present.

  15. #15
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    Quote Originally Posted by RCWilly View Post
    Pretty sure the stock receiver can only take 6V. Also, I think it's the ESC's job for the amp draw, so the receiver should be fine.
    awesome! thanks again man, i should really study basic electrical stuff haha.

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