Fried motor

[dresq1027]

I have an ml boatworks gsx version 2. I installed a SSS 3650, 2700kv motor, turnigy 90A esc, and a 440/3 prop, balanced and sharpened. Motor fried in 1/2 a lap. Everyone expected the esc to go, not the motor. Does anyone know why my motor cooked?

[Panchothedog]

You forgot the most important thing, the battery. How much juice were you trying to feed it. BTW under most any conditions that is too much prop for that size motor at that high of a KV. I use that prop ( octura 440/3 ) in my revolt 30" mono with a leopard 4074 2000kv. Runs good on 4 & 5 S.

[dresq1027]

I did forget that. 4s, 5000mah, 100c.

[Panchothedog]

Your motor kv is WAY too high for 4s. For that motor, you should be 2s or maybe 3s at the absolute max. Probably a 2 blade x-438 as well. How big is the boat. Your description means nothing to me. If it is too big for the smaller prop you might be better off to buy a different motor.

[dresq1027]

The boat is either 31 or 34 inches. I'll have to measure it. Motor is suppose to be able to handle 6s. The boat was built for impba p class. (Rules say less than 34 inches, 4s max). I never ran the boat before and I have a p cat with a dynamite 3650 2000kv with a 440/3 running 4s. That's why I tried that prop. I'm open to suggestions on props. I do have other motors as well.

[ray schrauwen]

P class limited uses a can up to 36mm x 60mm and most are rewound with higher temp wire. Both your esc and motor are not up to the task of the limited class let alone full P.

I will be running a Black Pearl 34" wood sport hydro with a Huff rewind and shortened Leopard 3674, Castle esc. Mamba Monster X converted to water cooling.

This setup will be carrying 2 packs of 4s 5000mah 4S2P. I will start with a ABC 1814 prop. Do you have a RC boat club nearby that they can direct you to what rules allow what motors etc?

[dresq1027]

Hi Ray. I am the VP at our local club. Most of us run gas and some old school nitro. Most of us are just getting started in electric and really don't know much. I know rpms are the name of the game with boats...get that prop spinning. I have a background in electronics, so I understand how this stuff works. I'm also familiar with the huff motors. There's a reason d13 is going away from the limited class and that's for another thread. When I considered my motor, the specs on this were max amps 63. Knowing manufacturers prorate their stuff for safety, I added 25%. That got me to 85. 90A esc would provide enough power. Also, 2700kv at 14.8 vokts is 39,960, no load rpms. Factoring in slippage of 20%, im at 32,000 rpms.
Just below the ideal 33,000 to 35,000 ose recommends Everyone I see runs 150 esc's. I personally feel that's overkill as it does not provide more performance and costs much higher. Where I struggle in knowledge is the props. What would be the best starter prop for this setup? As poncho pointed out, prop is too big. I do race at 1 club that does utilize the limited class for what it was designed for, so I want to keep it limited specific. I have never modified props outside of balancing and sharpening, but understand some of the physics. So if I have to modify a prop, I can with some direction. I appreciate your feedback Ray and hope to see you on the pond this year.

[Panchothedog]

If you are looking to keep it a legal class race boat ( I don't race or know the rules ) and the biggest motor allowed is 36 X 60, then get a motor that size. It will be stronger than a 36 X 50. Get the motor in the 1700 to 1900
KV range. I don't care what your calculations about rpm, 2700 is too high.
Also at 30" or more in length the X-438 is too small for that big of a hull.
I was trying to match it to your fried motor. For an Octura prop, a 2 blade
X-440 or X-442 with a 36 X 60 1800kv motor will work real good. There is a reason most of the racers you see are using 150 esc's,.The only reason your 90 didn't blow ( like you said people told you it would ) is because the motor went so quickly. You need the 150. I don't agree with you about price. Buy the OSE raider 150 for $59 and forget about it. Problem solved.I am not trying to sound mean or scolding. I am trying to get you to a working combination that won't burn up and cost you any more money.

[dresq1027]

Thanks Poncho. I'm putting a leopard 3660 motor in it with the raider 150. Gonna try it again. I did pull up the specs on many other 3650's at 2700KV. Turns out they're not rated above 3s. So I put too much voltage to it. So much for trusting a ebay ad I guess. Though I knew 6s was wrong because that's 60,000 rpms. They'll explode. But 4s puts it around the sweet spot ose recommends, so I didn't give it a second though. Turns out, it was too much. Now based on my new calculations with the leopard motor, it may exceed the 90A, and I'm not taking that chance. So raider 150 it is. As for props, what are your thoughts on a good starter? I have a 225, 230, 443, and an unknown that appears to be a 2017 (unless the guy engraved the year he bought it...lol). All 2 blades. The motor is 2550KV and came from a trusted reliable source. I was told to use that motor, but with a better esc. A friend is lending me the 150.

[koen]

if the 225 and 230 are steel prather prop they are way to big for your setup, start with tfl 4019

[Panchothedog]

I didn't know octuta made an X-443. Maybe it's not an octura. If its 43mm in diameter and a pitch of 1.4 times the diameter then it's your smallest prop. As stated above, the 225 and 230 are too big for that motor. At 2550 the kv IS STILL TOO HIGH for reliable 4-s running. That's only 150 lower than the motor you fried. With the props that you have I wouldn't use any more than a 3-s battery with the 2550 kv motor. Why don't you listen to sound advice. A big prop on 4-s and you are headed towards burning something up again. Run it on 3-s or get a lower of motor. A 1600 to 1700 motor would probably handle your bigger props ( 225 ). Once you get to where you can keep something on the water get your self a temperature gun and a voltage checker. Don't let anything (motor, batteries, or esc ) get over 135 degrees Fahrenheit and don't run your batteries down below
3.7 volts per cell. I have tried to tell you about all that I can. If you continue
to do it according to your calculation, I 'm afraid you have some EXPENSIVE
lessons to come.