Few quick questions about a brushless build.

[c.raynes]

So guys I'm a new comer here and this seems to be the best place to start off! You guys seem to be the most knowledgeable.

Now here is my question, I'm building a NQD jet boat using the Graupner mini jet drive which calls for a 540 sized motor. Now I have a Mamba max 5700kv brushless from my wheelie king. But I did blow up the ESC about three winters ago so the motor is mint and would love to get some use out of it. What amp ESC would you guys suggest to run in this application?? Also the batteries I wanted to use were the ones I currently have from my other NQD jetty I built, they're 3000mah 3s 35c packs, and I have like 6 of them so if i can utilize them also that would be excellent.

I appreciate your time and advice!

-Casey.

[jac4412]

Youre going to hit the moon with that set up....

Youll want what... like a 20 amp esc? Then I'd suggest a 2s lipo

[c.raynes]

so my setup would be way to fast your saying?? and wouldnt a 20amp just burn up?? I have a 35amp on my little 300 sized 3200kv motor in my other boat so i would assume i would need something like 80-100amp in this because its 540 sized??? and a higher kv?

[jac4412]

Hang on I read up on the motor... one sec

[jac4412]

Yeah you'll need like a 120 amp esc. The motor is going to want around 100 amps.

[c.raynes]

so is 2s recommended just for pure drive ability? or so i dont burn things up?

[keithbradley]

so is 2s recommended just for pure drive ability? or so i dont burn things up?

Honestly I wouldnt bother with that motor. It is better suited for 1/10 scale land rcs. Boats draw a lot more current than cars do, and when you try to spin a prop that fast (over 60,000rpm) the amp draw gets ridiculous. Even on 2s you are over 40,000rpm, which is higher than you want to be. I would be very surprised if that motor only pulled 100A on just about ANY setup, but no one can accurately tell you what amp draw will be without knowing more...like what prop you will be running...you would have a hard time keeping an esc in the boat with that motor, and it isnt a very high torque motor when compared to boat motors.

With boats, try to stay closer to 30,000rpm.

Maybe you can find someone with a better suited motor that wants to trade? Something like a supervee motor or blackjack motor...

EDIT: Actually since you want to use 3s batteries...a supervee or ul-1 motor (something around the 2000kv range) would be preferable. It wouldnt be a lot of RPM on 3sw, but it would be a lot of power for what you have either way.

[c.raynes]

Well thats fine I will go find a 2???kv motor instead. I would rather do it right once then wasting money and blowing things up.

So with a 2000ish KV motor what esc would you suggest to be running?? something in the 80amp range??? or higher more into the hundreds?

[keithbradley]

Im not sure what kind of load your jet drive will create, I dont have any jet boats, but if I were to run a setup like that with a prop that is suited for that motor, I would run the swordfish 120A. OSE sells them for $69, which is competitive with just about any esc and they perform great.

[jac4412]

Keith is right... typically they run what... 3600-3000 kv on the boat your using... on 2s.

2s is so you don't strain your system. If you want to use the 3s like keith said.. go with some lower kv.

The higher kv in boats have a higher top end... theyll suck in more amp draw and have much more strain during a run. There's a significant difference when your boat is going around and the prop goes through turns/hits a wave and goes out of the water... etc. The 5400 is alot of rpms for your boat. The suggested one will get your boat to run much better.

[Make-a-Wake]

If you need a 1/8" shaft motor, try the Feigao 540s. The 16L on 3s would work well in my opinion................around 28,000 unloaded rpms.

http://www.offshoreelectrics.com/proddetail.php?prod=fei-540S&cat=116

[c.raynes]

okay perfect looks like Ill go with that then! you guys are extremely helpful thank you! I definetly want to run 3s because I have so many packs already. so Ill check out that feigao motor for sure and that esc sounds perfect. Next paycheck ill be buying all the goodies!