Problems With a 4S Setup

[CraigP]

I’m having trouble getting a 4s setup to work in my DF Vortex 34 Hydro. When I built the boat last year, I set it up to run on 8S. It has ran great in that configuration. I used 4, 2S@5000mH packs hooked in series, powering a SW Pro+ 150A HV ESC with a cap Bank installed. I ran a Leopard 4074 1050kv motor turning a M445. It ran in the low 60’s. The data logger showed it running about 75-85A max.

So I wanted to try a P Sport setup, to contemplate the possibility of hitting a race or two. I installed a TP 4050 2310kv motor and put a smaller prop on it for test, an ABC 17-14-17. I reconfigured the batts for 4S-2P for 10,000mH. I upped the ESC to a SW Pro (no data logger, didn’t think I’d need it) 200A 2-8S. This thing is going into overheat protection running the first straight and going thru the first corner. I got it quickly to the shore, and the ESC, Motor, Caps, Motor connectors and batts are all very warm, about 130-135 degrees. The ESC was too hot to keep the fingers on it. I checked the water system and it’s fine. The boat has had a dual cooling system on it from day 1. The book says this motor is a 5D. I have the ESC set to 0 degrees of timing, 4S and LVC was 2.5V, just to take it out of the equation. It is a thermal limit cutoff, because I tried to run it again, and I had to wait for the ESC to cool down out on the water before it would give me another burst. Almost had to send the rescue boat out after it..

Does anybody see something I’m missing? Note: Boat is heavy, about 11-1/2lbs ready to run. But it pops right up on plane, always has...

[NativePaul]

To replicate your 8s performance on 4s I would use a similar motor with double the KV and use the same prop, I am not familiar with the ABC, but going from 1050kv to 2310kv you are trying to spin it another 3500rpm faster with half the voltage, so it wouldn't surprise me if the amps are more than doubled. The bigger motor will have a higher IO/KV, and likely has the torque to get closer to its theoretical RPM, so will pull more power still to do so.

I would say prop down, but I expect that it takes a lot of thrust to pop that 11-1/2 lb boat up onto plane, if the ABC is smaller as it should be with the higher RPM, it may be slipping considerably more and consuming more power for the same performance, so dropping KV or weight seems like a better way to go.

[Fluid]

If it is overheating that fast then water cooling has nothing to do with it. It acts like it is still running on 8S, are you certain the four packs are configured correctly? This is no insult, I’ve seen very experienced racers make this mistake on occasion.

Another possibility is a shorted motor; I’ve seen this with brand new motors from at least four makers and with used motors, it happens. I ran my Vortex33 on 4S with a TP 4050/1900 motor, 4S2P/5000 and IIRC a 1916 prop.

This kind of thing can be tough to diagnose from a thousand miles away.


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[CraigP]

Certain it’s not on 8S, measured the volts at the cap Bank. What bum luck if it is the motor. By my calculations, it should have been running 150-160A. The ESC should easily handle it. I checked TP’s website and verified it is a 5D motor. But all the signs, everything indicates the current is way out there. I’ve checked the batts on my charger and they are measuring 2-3mOhms, so they are strong, and it’s a brand new set. The fact the same ESC runs the 8S setup just fine, I think the advice from both you guys is correct. Jay, I think it’s the motor and Paul recommends getting a 2100kv motor, a better match to 4S anyway.

I gotta tell you guys, I’m not sure it’s worth trying to make this boat meet class. It’s just a great 8S. I ran it today after putting it back on 8S and it ran for almost 6 minutes with the batts going to 3.7V... But I’m sure my curiosity is going to get the best of me, and I’ll have to know what the problem is. I sure wish I still had my uOhm Meter, maybe I could pick up a difference in the winding resistance. Thanks for chiming in, it helps...

Note: The batts today are 2S@8000mah. No way almost 6 minutes in 5000’s!

[CraigP]

If it is overheating that fast then water cooling has nothing to do with it. It acts like it is still running on 8S, are you certain the four packs are configured correctly? This is no insult, I’ve seen very experienced racers make this mistake on occasion.

Another possibility is a shorted motor; I’ve seen this with brand new motors from at least four makers and with used motors, it happens. I ran my Vortex33 on 4S with a TP 4050/1900 motor, 4S2P/5000 and IIRC a 1916 prop.

This kind of thing can be tough to diagnose from a thousand miles away.


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I’m going to check on that motor Jay, 1900kv and a bigger prop sounds like a better play..

[CraigP]

TP motor, still thinking about that... Once bitten twice shy. But they are built very strong. They have a 4050 1950kv, 6D and they have a 2100kv, 3Y. I’ve had very good results with the Y winding... The 2100 is exactly double kv of the 8S motor. Thoughts?

[785boats]

I always find that the Swordfish ESC's run cooler & more efficiently, when the timing is set on 'Auto'. Perhaps give that a try. But it does sound a bit more serious than a timing issue.
I've never used a motor over 2200kv in any of my 4s sports hydros & I usually spin an M645 or Y547 on them with a SeaKing 180A ESC. No heating problems there.
So as others have said, it may be the motor, or even the ESC when it is in 4s mode.

[CraigP]

I have tried it in the Auto timing mode, didn’t make a difference. Your T-180 is exactly what I would have used if the boat wright was under 10lbs. Jay, do you know how much your Vortex weighs race ready? I added to the sponsons, basswood frames and 0.020” T6061-T6 sheeting. I weighed before putting on, it only added about 130g per side. I swear I think the paint is what fattened her up!

I thought last night about PWM frame. It’s at the default 8Khz right now, but if that motor’s inductance is low enough, it might be going into saturation. I wasn’t at full throttle much, it’s the first lap, or try at it, so I’m running about 3/4 throttle average. What are the thoughts on using a 12Khz PWM frame timing?

[TRUCKPULL]

Craig

Is it possible that the motor mount screws are too long and touching the windings, causing a short in the winding?

I almost had this problem yesterday when changing a motor from one manufacture to an other.
I had to add a 2mm thick washer on the screw to be clear of the winding.

Larry

[CraigP]

I checked that too Larry. Even took the end bell off to inspect. I found the TP motor has a slick plate in front of the winding to prevent that from happening. Anyway, the end of the screws doesn’t extend out past the inside of the end bell. I was wishing that would be it and I would find the “smoking gun”! I appreciate the thought and response, at least I’m doing and checking what others would do. Looks like I’m going to have to get another motor if I want to try and resolve...

[Jesse J]

My vote would be for a 1800-1900 4070 can and a t180 v2 or similar. Open P sport hydro is much different than p limited. And doubling the kv at half the voltage will kick up the amps.

I’m racing a ML335 With a nue 1521 1.5d (1860 kv), I can run an octura x450/3 on a t180 v2 and finish my race with temps <130f, mid to upper 50s.

[CraigP]

So are most people running 100mm motors in a P Sport? Man, I’m way off! I’ve got a 4074 in there now running the 8s setup and it’s plenty fast. Seems a TP 4050, that’s an 83mm motor, would be plenty. There’s a 1950kv available. I’m concerned about weight with a motor that big. Looks like it’s not the right build to race it. I’m thinking about getting the new TP for the 8S setup, a 1050kv. I do run some heat on the Leopard 4074. Thanks for opening my eyes up!

There’s a TP 4060 1050kv available... That should make a killer 8S setup! It’s a 93mm motor...

[Fluid]

I dont remember what the Vortex weighed, but it was over 10.5 lbs. As for motors, some do run 100mm motors in P, but I’ve only run 82mm (and very occasionally 93mm) motors in my oval P Sport boats. But motor size isn’t your problem, not with overheating so soon after launch.

The lower PWD setting the potentially lower the ESC temp will be (less switching), and I can’t remember using anything higher than 8 except in one SAW boat. But it’s free to try a higher setting.


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[CraigP]

Yes, I think it’s a bad motor. I have a UL-1 I’m putting together that could be fun to race in P Limited. That’s a 4S setup. I just wish the sport would migrate to higher voltages and leave these amperage problems behind.

BTW, I’m also starting on another Vortex33 that will have twin 3650’s in it with a single center mount rudder. Ive always wanted to build a twin and I really enjoy driving the hydros. No class for it, but plenty to learn from! I was thinking of documenting the build on the site, just take my time. Looking to make it as light as possible.

Thanks to everyone!

[TRUCKPULL]

Craig

In my "P" Sport I run;
NEU - 1515 - 1y - 2200kv
Timing - 15 Degrees
240 amp Castle ESC
4S 2P - 5000's - 70C (10,000 total)
45mm prop
This is my race setup, average amp draw is about 170 Amp's,

GPS speed in race trim 69 MPH

Larry

[CraigP]

I blew it getting that 2310kv motor... That’s a big motor you got in there Larry! Thanks for sharing that info.

[Fluid]

BTW, I’m also starting on another Vortex33 that will have twin 3650’s in it with a single center mount rudder. Ive always wanted to build a twin and I really enjoy driving the hydros. No class for it, but plenty to learn from! I was thinking of documenting the build on the site, just take my time. Looking to make it as light as possible...

Actually, NAMBA Sport Hydro rules state that the drive train is up to the racer. P Power rules allow twin motors. But I’d clear it with your local club first. I had contemplated doing this with my Vortex when I first bought it, there’s plenty of room in the hull. Just try spinning both props in the same direction for oval racing, the twin rigger guys all run em that way for improved turning. Lots more prop options that way too.


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[CraigP]

Good stuff Jay, thanks! I got small motors, 3650’s going in. I did a calculated weigh up and this combo should get me to 10.5lbs, lighter than the 8S boat. It’s a 4S boat, 2090kv

What direction do they turn them, CCW?

[TRUCKPULL]

Yes - CCW.

Twins are legal in "P" for NAMBA but not IMPBA
IMPBA only allows twins in "Q" and above.

Larry

[Fluid]

Actually, IMPBA specifies that all Sport Hydros can only use one motor. F.2a in the current book.



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[CraigP]

I’m sure there would be some “discussion” if I showed up with this boat! But it’s just two, tiny motors, lol!

[Fluid]

Twin R/C sport hydros are very rare. This is the only one I’ve seen, and it’s an 18” NQD. They didn’t get the memo on prop rotation.....but then again it’s not an oval racer.

88D51870-79B6-4E7E-AB8B-9F8A8A57858D.jpeg

[TRUCKPULL]

Actually, IMPBA specifies that all Sport Hydros can only use one motor. F.2a in the current book.

Sorry Jay you are correct. I was thinking about my twin Cat.

Larry