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  1. #1
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    Motor Temp: 254 F Whoops!

    I finally got a digital thermometer to monitor the motor and ESC temps, got a reading of 254 degrees F on the motor... whoopsie. Did some reading on the subject and learned I did exactly everything right to get the motor as hot as possible.

    Rustler 4x4 with: Valineon VXL-3s brushless motor and ESC, Tekno RC metal driveshafts (x4) with metal wheel hubs (I stripped out the plastic ones), Sledgehammer tires, 5000mAh 3s LiPO battery, stock 10/54 gearing, plus some other misc parts.

    I was running it on grass for about fifteen minutes when I decided to stop and check the temps. According to what people said online it should have blown up that hot but it was working fine, and that wasn't the first time I've run it that same way either. I wouldn't be surprised if it's holding on by a thread at this point, I should probably get the motor rebuild kit preemptively huh?

    Anyway, any ideas other than not running on grass to keep that temperature down? Gearing change? Don't go full throttle? Thanks in advance.

  2. #2
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    First off, thanks for the post. This is a remainder to us all that grass is the killer of all motors.

    I would also like to add that your Sledgehammer tires are quite a bit bigger then the stock tires, now you'd think that this would allow your car to drive over the grass easier but what it really ends up doing is changing the drive ratio and putting more stress on the driveline and motor (which is why the Hoss, that comes stock with Sledgehammer tires and is built off of the same chassis as the Rustler 4x4 comes with a much larger motor). You could solve this problem by A: changing your gearing, B: turning in your power system to Traxxas in exchange for the Hoss power system for half off, C: putting back o your stock Talon EXT tires, or D: buy a cooling fan for your motor.

    All of those options would work, though they may not completely eliminate your overheating problems it will at least help to alleviate them. Just remember that your driving style will always have to factor in when it comes to how your motor will react temperature wise.

    If I were you I would choose to turn in the stock Rustler 4x4 power system in exchange for the Hoss power system for half off, I provided the link to where you can do that below.

    https://traxxas.com/powerup

    I hope that this helps!
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  3. #3
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    Ok, I just checked with an employee at Traxxas and he said that unfortunately you are not able to exchange for the Hoss power system, knowing this I would say that it's best to just buy a bigger motor.
    The present is theirs; the future, is mine.

  4. #4
    RC Qualifier Calebs0615's Avatar
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    If the hoss uses the 540xl system, you can trade that in using the power up program. Im not sure why he would tell you that you can't..

    Is the esc different than the one they offer?

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  5. #5
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    Quote Originally Posted by Calebs0615 View Post
    If the hoss uses the 540xl system, you can trade that in using the power up program. Im not sure why he would tell you that you can't..

    Is the esc different than the one they offer?
    The motors are different then what they offer on their form, the Rustler uses the 3500kv system while the Hoss uses the 2400kv system. They use the same ESC though (VXL-3s) just the Hoss has a fan.

    https://traxxas.com/sites/default/fi...orm-Fields.pdf
    The present is theirs; the future, is mine.

  6. #6
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    Thank you for the feedback! Given that the grassy area and gravel road are the only driving options around me I think springing for a larger motor is the preferred choice. I'll see if I can get away with the ten tooth pinion since it has a set position for aligninment and to go down to a 9-tooth I'd have to manually set the mesh. I've already done the power up program to go from the stock rustler Titan 12T brushed motor to the VXL-3s brushless motor, I'm wondering if they would even let me do it again.

    It seems the voltage goes down with the larger motors, I don't know why or what effect that has.
    Valineon VXL-3s 3500kV
    Valineon 540XL 2400kV in the Hoss 4x4
    2200kV motor in the E-Revo

    I'm not sure if the E-Revo motor is compatible with the rustler frame or the VXL-3s ESC. Down another research hole I go.

  7. #7
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    Simply running 2s instead of 3s lipos will help significantly, though, as many of us, prefer the power/fun-gains of 3s. I have a 28k RPM surpass hobby fan blowing over an integy heatsink in my rusty 4x4, still doesnt take long on warm days to hit the 150*F mark. And if the motor with HSF isnt heating up on cooler days, the esc will kick you down to half power due to being over 120*F.

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  8. #8
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    This was probably my fourth run using 3s LiPOs after owning the rustler and using NIMH batteries for a few months. I definitely want to do what I can to keep using the 3s, so much power! Plus I'd rather spend the money on upgrades than more batteries, seeing as how I just bought the 3s batteries and charger. I'll look into that heatsink and fan, thanks.

  9. #9
    RC Qualifier Calebs0615's Avatar
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    Quote Originally Posted by ElectricPropils View Post
    The motors are different then what they offer on their form, the Rustler uses the 3500kv system while the Hoss uses the 2400kv system. They use the same ESC though (VXL-3s) just the Hoss has a fan.

    https://traxxas.com/sites/default/fi...orm-Fields.pdf
    Oh i see. I thought the 540 motor was the 2400kv but the guy after you said it's the 2200kv one. I get it now. Thank you guys.

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  10. #10
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    Quote Originally Posted by Calebs0615 View Post
    Oh i see. I thought the 540 motor was the 2400kv but the guy after you said it's the 2200kv one. I get it now. Thank you guys.
    The Hoss comes with the 2400kV 540XL motor and the E-revo 2.0 comes with the 2200kV motor.
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  11. #11
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    Quote Originally Posted by TTTFFF View Post
    It seems the voltage goes down with the larger motors, I don't know why or what effect that has.
    Valineon VXL-3s 3500kV
    Valineon 540XL 2400kV in the Hoss 4x4
    2200kV motor in the E-Revo

    I'm not sure if the E-Revo motor is compatible with the rustler frame or the VXL-3s ESC. Down another research hole I go.
    The E-revo motor is pretty big and I highly doubt it would fit in the Rustler 4x4

    kV stands for RPM per volt, that this is basically saying that if you want the same speed you need a higher voltage for the motor. As you get a motor with a lower kV it can generally be stated that your car will run cooler while running under the same load though it will also be running slower. I'm not the most knowledgeable in this subject but you can always look it up on google if you are really interested. I would get the 540XL out of the hoss if I were you. The cooling fan for the ESC would also be a nice addition if you aren't bothered by spending money.
    The present is theirs; the future, is mine.

  12. #12
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    Several other options for VXL-3s cooling are available, and usually quite a bit cheaper than the TRX version. Like this combo deal! https://www.amazon.com/dp/B07GL8VJ2T...YRRRTQTL&psc=1

    Also, from what ive been reading, as i understand it, most motors rated for 3s and up, are your higher kv ratings, whereas a normal 4s-6s setup would have a motor with say, a 1853kv motor. And they run cooler, AND SOMETimes faster, due to higher voltage??

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  13. #13
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    Quote Originally Posted by ElectricPropils View Post
    The E-revo motor is pretty big and I highly doubt it would fit in the Rustler 4x4

    kV stands for RPM per volt, that this is basically saying that if you want the same speed you need a higher voltage for the motor. As you get a motor with a lower kV it can generally be stated that your car will run cooler while running under the same load though it will also be running slower. I'm not the most knowledgeable in this subject but you can always look it up on google if you are really interested. I would get the 540XL out of the hoss if I were you. The cooling fan for the ESC would also be a nice addition if you aren't bothered by spending money.
    Thank you for the explanation and recommendation. I should add to my original post that I also have a dust cover over the internals and first ran a NIMH battery through it before swapping to the 3sLiPO. Both of those definitely contributed to the heat gain.

    By swapping to the 540XL would I expect a 31% decrease in top speed? (2400kV/3500kV)

  14. #14
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    Quote Originally Posted by TTTFFF View Post
    By swapping to the 540XL would I expect a 31% decrease in top speed? (2400kV/3500kV)
    Not exactly, that number is without load so you will most likely see a difference around 25% at top speed, the motor will definitely run cooler and it will handle 3s much better then the stock motor (more torque/power). If you want your speed back you can gear up, and even gearing to the same speed as the stock set up you will see a reduction in motor temps with the larger 540XL motor.
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  15. #15
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    Quote Originally Posted by ElectricPropils View Post
    If you want your speed back you can gear up, and even gearing to the same speed as the stock set up you will see a reduction in motor temps with the larger 540XL motor.
    Good to know! I was curious of this exact scenario, thanks again.

  16. #16
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    No problem, I'm here to help!
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  17. #17
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    No problem, I'm here to help!

    Here is a thread I started a while ago that has a few things about motor temps and what's safe, you may have to skip around a few posts but there is some really interesting information in there.

    https://forums.traxxas.com/showthrea...change-gearing
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  18. #18
    RC Turnbuckle Jr. olds97_lss's Avatar
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    Getting a longer motor even with the same kv would help, but typically, the kv rating does drop the longer the motor gets. At least it seems to.

    If money is an issue, you can find other 3670 sized motors. Even a 3665 would likely give you more torque and run cooler. My velineon 3500 from my stampede died on me after running it on 3S a few times in my eJato. I swapped it out with a hobbystar 3100kv 3665 and geared it up a bit more. It really rips now and with a fan, stays relatively cool.

    https://www.rcjuice.com/hobbystar-36...aterproof.html

    Never tried the 3670:
    https://www.rcjuice.com/hobbystar-36...aterproof.html

    Not bad motors for $40. Keep in mind, the output shaft is 5mm, so you'd need new pinions. May need 4mm bullets as well for your esc, I can't recall what it uses. My vxl-3s kind of died on me after a few years of use. It skips/hesitates a lot, so I quit using it.
    https://www.youtube.com/c/olds97lss

  19. #19
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    Quote Originally Posted by TTTFFF View Post
    Anyway, any ideas other than not running on grass to keep that temperature down? Gearing change? Don't go full throttle? Thanks in advance.
    Cut grass short. 4” grass is the scale equivalent of driving your 1/1 car
    through 4 foot saplings a few inches apart.
    The drag on the suspension arms is huge! Lots of friction every where else under there too...
    Taller tires...
    Shock bottoms moved in for more ground clearance...
    Lowest stock gearing, forget what it is right now.
    Training mode???
    Last edited by fortunespoonz; 10-16-2020 at 06:15 PM.

  20. #20
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    Quote Originally Posted by Trx4newb View Post
    Several other options for VXL-3s cooling are available, and usually quite a bit cheaper than the TRX version. Like this combo deal! https://www.amazon.com/dp/B07GL8VJ2T...YRRRTQTL&psc=1

    Also, from what ive been reading, as i understand it, most motors rated for 3s and up, are your higher kv ratings, whereas a normal 4s-6s setup would have a motor with say, a 1853kv motor. And they run cooler, AND SOMETimes faster, due to higher voltage??

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    Sorry! What i meant was most motors for 2-3s have higher kv numbers, whereas, the 3-6s motors are anywhere from "1650/1700, 1800 on up through 3300kv. but when u read around, a lot manufacturer will tell u their motor/esc combo , CAN run 3s but not recommended, as its their ESC that can hang, not necessarily the motor

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