200a ESC won't take WOT

[fenalx]

Here's an update.

9xl, prather 215 prop, 4s, 200a ESC.

At long last. Can drive at WOT.

Still had to swim however - sea was quite choppy and i decided to try turn at high speed. Boat rid the wave, and flipped.

Was gonna consider a bigger prop, for use when sea is calmer.

Would you suggest Octura X4 of X6 series?

Thanks

[mickvk]

The "rating" of a motor is the maximum amps the manufacturer wants the motor to run, not the most it will draw. Put a big enough prop on it with good enough cells and you'll draw 200+ amps no sweat.


.

I don't understand it entirely but you are right about that. My "68A max" motor (same as the OP) was drawing almost 100A and I don't think it's over propped... ??

I understand that in the normal operating range, the draw is interrupted while cycling through operation keeping the amp draw at the rated max.

But if you slow the RPM down by over propping the motor, then the duration of draw in each cycle gets extended causing the rated max amp value to be exceeded.

[mickvk]

I am using the same boat/motor from that ebay seller. I'm still trying to figure out a good setup. My ESC was over heated very quickly (170F in under one minute) so I propped down from the 443 (44mm) to an Octura Y536 (36mm). Also, I had very little throttle resolution - it was like on or off. So I upgraded the ESC to a Castle Hydra 120. On 4S, the boat screams pretty nicely now. Here's a graph of a one minute run (in very choppy water hence all the spikiness). I think I still have ESC temp problems because I can't hold the throttle wide open - I'm still working on stability issues with center of gravity, stinger angle, etc. At partial throttle, I understand the ESC efficiency drops dramatically and heats up. (note: this graph of a one minute run does not show a temperature problem, but in other runs in the same configuration, ESC temp exceeds 150F.)

Here's a picture of a one minute test. TempA is Motor. TempB (yellow) is the ESC. Temp C is the battery.


Does anybody know how many poles this motor is? There are detailed specs here, but nothing to indicate poles.

http://www.fsd-motor.com/en_productview.asp?id=324

I have the EagleTree setup for 2 poles. Theoretically should be 40,256 RPM at no load but is hitting almost 43,000 in the water (measured off the wires, not optically). I expected the value to be 32,000 under load. Maybe that's just because the prop was out of the water so much? Like I said, very choppy conditions on a large lake.

[fenalx]

Here comes my update on same setup with smaller prop - still same problem.

Will take your recommendations and switch to 9XL.

Thanks all for your input.

[Fluid]

As others have said, wrong motor. For your setup a 10XL 540-sized motor would do fine. Speeds would be in the 40s and run time around 3-5 minutes depending oh how you run it. A hotter motor will stress you packs too much. A 10XL pushes my 30" cat to 45+ mph on 4S no problem.

Depending on the speed you want, 4S is plenty for a 32" hull. My 33" mono runs 50 mph on 4S just fine, 3-4 minutes in race trim. Going to 6S can raises your speed, or it can extend your run time - but the cost of converting to 6S may be higher than you want.

The "rating" of a motor is the maximum amps the manufacturer wants the motor to run, not the most it will draw. Put a big enough prop on it with good enough cells and you'll draw 200+ amps no sweat.


.

[ozzie-crawl]

i run a 32" df hull on a 9xl 4s 1p, i only do short 2-3 min runs with a modded x447/3 prop (mid to high 40s) a x440/3 would give you longer run time low 40s

[ED66677]

Douggie is right!

I would change out your ESC for a high voltage one and run a 580L motor on 6S

that is certainly the safest solution that will give you plenty of power

The problem is the length of hull with dubious electronics

the 200A ESC can do it without problem, I've seen bigger hull than that running fine with it, but a Feigao XL will be on the edge for this big hull
check this thread http://forums.offshoreelectrics.com/...ead.php?t=4159

[fenalx]

Lipo C ratoing is 20C. I switched off low voltage cutoff NorthernBoater becasuse i thought of that. I had tried running on 2S only, but still got same result.

The problem is definately overpropping. Gonna try a prather 215 this weekend, and post results

[Flying Scotsman]

The problem is the length of hull with dubious electronics. It will run fine with the expected goals of the manufactuers market. If you want to hop it up...change out all the drivetrain and electronics

Douggie

[NorthernBoater]

What is the C rating for the batteries. You may also be triggering the low voltage cutoff.

[sailr]

Go down to an octura X440 or Prather 215. You are overpropped for that KV. The higher the KV, the smaller the prop as a rule. 2760KV is more suited for 3S lipo. 4S is a bit over the edge.

[fenalx]

Thanks for your updates.

I measured my currrent prop, and it is 43mm diameter by 51.6mm pitch. I want to give it a try with a smaller prop before getting into the expense of changing motor.

Will stop test should i get a power cut at WOT in order to preserve ESC. Then i would have no option but to get a new motor and motor cooling jacket.

Will keep you posted.

[Flying Scotsman]

I would change out your ESC for a high voltage one and run a 580L motor on 6S.

Douggie

[ED66677]

you want to have the prop at 30-35000rpm, 10XL under 4S gives 4x3.7x1668=24700rpm unloaded, unders 5S around 30900rpm
if he wants to stay with 4S then the 9XL (1853KV) will give 27500rpm, in fact the 8XL gives a better rpm but will not be able to spin a big enough prop, the 9XL will certainly! too small of a prop means more slippage and poor efficiency.

[NorthernBoater]

Can you be more specific about the batteries?