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Thread: Burst rate of motors

  1. #1
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    Default Burst rate of motors

    If a motor has a continuous wattage rate of 2000 and a burst rate of 3500, will this motor run at the burst rate for
    the entire race. or is it like a battery that can only burst for 10seconds before it bursts into flames.

    then if i have a 5000 mah 40c discharge battery with a 60c burst, is that much burst needed before the batteries burst into flames.
    what it comes down to it, can i run just a 5000 mah 40c discharge battery without a burst rate
    this is the leopard 4082 im thinking about buying to use in a 29" sprintcat hull
    Last edited by sprintkat; 02-25-2012 at 10:39 PM.

  2. #2
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    Motors are damaged by heat. That's a function of current, not voltage. Motors can be run at much more than their ratings depending on the quality of their insulation. As an example, the UL-1 motor is rated at a maximum of 80 amps. We see over 100 amps frequently on P spec boats. The motors often last more than one race season before they fail. For non competition running, I would stick to the manufacturer's rating. A 40C current from a 5000 mah battery is 200 amps. 60C is 300 amps. You need a serious speed control to be able to exceed that, even for a short time.

    Lohring Miller

  3. #3
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    A Leopard 4082 2000KV on 4S2P (two 4 cell 14.8V batts in parallel) will get you 29,600 RPM. You may want to look at Leopard 3674 2200 (32,560 RPM) and 2650KV (39,220 RPM).http://www.leopardhobby.com/product/...ionID=01020203. I've ran them in my Miss GEICO & Apparition with great performance. For LIPO batts, I recommend Turnigy Nano Tec 5000mAh 65-130C. ESC, the new Turnigy 180Amp with extra capacitors gives you a great bang for the buck and can easily handle a 4-6S LIPO setup. Should easily get mid 60 MPH out of your Sprintcat.

    Many ways to skin your cat's power requirements. This is one. JIM
    JIM MARCUM: NAMBA 777; EX? SoCal FE Racers Club; D-19; Official 2012 NAMBA FE Nationals Rescue Diver; Purple Heart Viet Nam Vet; Professional SCUBA/HOOKA Diver, KELCO, 1973-1978; BBA 1978, Magna Cum Laude; MBA 1980 w/honors; Retired DOD GS1102-12 Contract Specialist

  4. #4
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    If the heat is 45 seconds long, the motor may last. Here is an example - my P Sport Hydro with 1521 motor (1750W continuous/3500W surge) will run a mile heat with warmup lap pulling an average of 2800 watts without problems - the motor has lasted two racing seasons. But, it is getting pretty warm at the end of the heat in summer weather, around 145*F. A Neu can handle that temperature just fine, lesser motors perhaps not. That isn't the contimuous rating - nor the burst rating - but in between. YMMV.




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  5. #5
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    Jay, should get my first full runs with a Leopard 3674 3270KV 4S2P in my Apparition, and a Leopard 3660 4650KV 2S2P this week. Both are SAW builds, so they will get a bit hot. Will take temps and speeds and let you know if they fry or not. Geeze, I hope you have underestimated Leopards survivability. If I can get the speed I need & last 45 seconds thats OK with me. Each SAW pass only lasts 10+ seconds full throttle. Plus, at $80 each I can afford a couple of spares.

    If the 3674 3270KV 4S2P survives, the lower KV models should work out OK for SprintKat. I respect your opinions Jay, but I've yet to fry any of my Leopards. JIM
    JIM MARCUM: NAMBA 777; EX? SoCal FE Racers Club; D-19; Official 2012 NAMBA FE Nationals Rescue Diver; Purple Heart Viet Nam Vet; Professional SCUBA/HOOKA Diver, KELCO, 1973-1978; BBA 1978, Magna Cum Laude; MBA 1980 w/honors; Retired DOD GS1102-12 Contract Specialist

  6. #6
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    Jim what esc will you be using with the 3674-3270kv on 4s, i was looking @ some of the 3674 motors to run SAW with. With poss 2200kv on 6s or 3270kv on 4s. I know the 3270kv is quite a high amp motor which is why i was also looking at the 2200kv on 6s to get the amps lower. Martin.

  7. #7
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    What voltage and what motor kv are you planning on?

  8. #8
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    i have them -leo 3674 3270kv- in my H&M intruder twin with swordfish 200Amp.3s for sport running you can run all day.4s for SAW im running 2s+2s in each motor 6000mah nano and im using all the capacity until the lvc...esc and motors come out in reasonable temperature...not very hot but very warm.but that is acceptable for 48k rpms turning motors.the only thing is that i changed the bearings with some koyo japan bearings-true 60k bearings..
    here some testing videos.
    3s
    http://www.youtube.com/watch?v=i-lFj...ature=youtu.be
    4s
    http://www.youtube.com/watch?v=XGuyC...ature=youtu.be
    H&M Intruder S twin Leopard 36/74/3270 @ 3S-HIFEI 200A
    MHZ mystic 114-TP4050 5D-HIFEI 240A hv ESC- @ 2 x 5S
    BANDIT S"love boat" LEHNER POWERED.. RCFASTBOATS.GR MINI COOPER CAT

  9. #9
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    Sick backflips man. Looks pretty strong.

  10. #10
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    ...Geeze, I hope you have underestimated Leopards survivability. If I can get the speed I need & last 45 seconds thats OK with me. Each SAW pass only lasts 10+ seconds full throttle...
    Jim, this thread is about oval racing, not SAW passes. Of course it all depends on the amp draw and the time needed for heat buildup. FWIW my 4S record runs at 82 mph were right at the surge rating for the motor of 3500 watts. There is plenty more there - but not for oval racing.



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  11. #11
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    Quote Originally Posted by DINO7 View Post
    i have them -leo 3674 3270kv- in my H&M intruder twin with swordfish 200Amp.3s for sport running you can run all day.4s for SAW im running 2s+2s in each motor 6000mah nano and im using all the capacity until the lvc...esc and motors come out in reasonable temperature...not very hot but very warm.but that is acceptable for 48k rpms turning motors.the only thing is that i changed the bearings with some koyo japan bearings-true 60k bearings..
    here some testing videos.
    3s
    http://www.youtube.com/watch?v=i-lFj...ature=youtu.be
    4s
    http://www.youtube.com/watch?v=XGuyC...ature=youtu.be
    You sure like running 10 pound missles right at your kneecaps.....................
    NEED PARALLEL CONNECTORS?? QUALITY 5.5MM, 8MM, 8 AND 10 AWG, GET THEM HERE: https://forums.offshoreelectrics.com/...est!&highlight=

  12. #12
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    Just chiming in - At work can't watch youtube vids here - My browswer is to old .
    Necessity is the mother of invention.............

    Youtube Video's http://www.youtube.com/user/Titanis2000

  13. #13
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    Jay, I realize that my friend. Thats why I suggested the 3674 2200KV Leopard for Sprintkat as a slightly higher revving motor than the 4082 2000KV. It should make a good oval/offshore boat running in the low 30K RPM range.

    Martin, I will probably use a T180 with an extra bank of 6 Rubycon ZLH 35V 1000 uF caps. Also have some Nichicon HE 35V 2200 uF due in & will use my Data Logger to see how they compare. JIM
    JIM MARCUM: NAMBA 777; EX? SoCal FE Racers Club; D-19; Official 2012 NAMBA FE Nationals Rescue Diver; Purple Heart Viet Nam Vet; Professional SCUBA/HOOKA Diver, KELCO, 1973-1978; BBA 1978, Magna Cum Laude; MBA 1980 w/honors; Retired DOD GS1102-12 Contract Specialist

  14. #14
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    Here is my take. DON'T listen to burst ratings. Most of those numbers are HIGHLY inflated.
    Steven Vaccaro

    Where Racing on a Budget is a Reality!

  15. #15
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    Steven has a valid point, most of the Chinese motors seem to have inflated ratings. I can attest that the Neu ratings are spot on, as are at least some of the Castle numbers. But any motor can go induction furnace.....



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  16. #16
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    I think when racing at short 2 minute racing durations, I believe Neu's numbers are actually underrated.
    Steven Vaccaro

    Where Racing on a Budget is a Reality!

  17. #17
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    "induction furnace". That's a great phrase Jay. That must be what happened to my Blackjack's Sky Wing 150 Amp ESC yesterday. It didn't "really" smoke the ESC & blow the capacitors literally off, & start a fire. It was merely transformed by an induction motor into an ESC furnace.

    Yesterday I was running my Leopard 3660 4650KV on 2S2P for 6 passes - about 3 min, and the motor registered 78 F, the batts 70 F. The wind picked up making 6-8" chop & I decided to go slower & "play" offshore awhile longer. Was in a hurry and figured it was OK to not tape down the hatch. After another 5 min - same charge - I flipped it 360 knocking the canopy off. As I waded out to retrieve it, smoke started comming from the hull & by the time I got to it the there was about an inch of water in the hull and the ESC was literally in flames. Postmortum showed the 12 AWG positive ESC lead had fried the boards & blown the capacitors completely off. The twin canopies were 3/4 full of water & almost sank before I could reach it.

    Lessons learned: 1. ALWAYS tape the damn hatch down. 2. Use a T 180 on smaller setups and sell remaining Sky Wings. 3. Slilcone all around the Black Jack canopies or you can loose the whole hatch. 4. Blown caps & ESCs stink bigtime. Stunk up my car, then my man cave at home. 5. A good rag & paint thinner will remove the stinky black crap covering everything inside your hull and won't melt your flotation foam. 6. Wives have zero patience with idiots that bring a stinky boat inside the house.

    Footnotes: 1. An un-taped hatch on the Black Jack will soon result in a hull full of water. 2. An apology and a dozen roses won't get you out of trouble if you violate lesson 6. JIM
    JIM MARCUM: NAMBA 777; EX? SoCal FE Racers Club; D-19; Official 2012 NAMBA FE Nationals Rescue Diver; Purple Heart Viet Nam Vet; Professional SCUBA/HOOKA Diver, KELCO, 1973-1978; BBA 1978, Magna Cum Laude; MBA 1980 w/honors; Retired DOD GS1102-12 Contract Specialist

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