Motor & Batteries getting hot

[Fade2Gray]

Hi Everyone,

I have built a Mini Mogli (my first built boat) - The Mogli seems to run fast (similar to a super vee) and handles well. I am using a stock SuperVee motor and SuperVee ESC and a Spektrum TX/RX.

I wanted to ask the pro's out there for some advice as to why the motor and batteries get extremely hot after taking the boat back into shore? I believe this has caused a cell to burn out in both my IB4200 packs and in my IB3800 packs which is now a concern.

I have the waterline going into the ESC and then into the Motor. Run time is generally around 8 minutes. A steady water stream is constantly flowing from the water outlet. There doesn't appear to be any binding with flex shaft. Regularly l grease the flex shaft and put a small amount of oil in the stuffing tube. The ESC stays cool and no where near as hot as the motor and packs.

I would greatly appreciate any advice on preventing the motor from heating up. To give you an idea of the motor’s temperature, the water jacket is extremely hot i.e. You could not touch it with your finger for very long.

I have attached a couple photos to give you a picture view.

Thanks in advance.

[obrien]

sounds like you may be over proped

[ReddyWatts]

How much slack/gap are you leaving between the strut and drive dog? The flex shaft will shorten under torque. It could be causing motor/drive line drag on the water, but feel free when on the bench.

I do not see a thrust bearing/washers to keep pressure off the motor bearings?

[Fade2Gray]

How much slack/gap are you leaving between the strut and drive dog? The flex shaft will shorten under torque. It could be causing motor/drive line drag on the water, but feel free when on the bench.

I do not see a thrust bearing/washers to keep pressure off the motor bearings?

I leave around 3mm gap between the strut and drive dog. Correct, l don't have a thrust bearing/washers.

The prop l have used here is x642

[Rex R]

super vee motors tend to run hot...however another thing that can cause problems is, how the cells are connected to each other (in the pack). I've seen packs come back over hot because they had welded tabs(as opposed to battery bars). btw your drive gap is not apparent in the pic.s

[Fade2Gray]

Thanks Rex, l appreciate your feedback.

Both IB3800 and IB4200 packs had battery bars, in fact the Lipo that l am using (PolyRC 30C 4500mAh 2S1P) also heats up, l am worried that one of the cell within my new Lipo might go similar to both of my IB packs.

I have a supervee with stock motor and cooling jacket, the motor doesn't get hot like my Mogli, in fact the SuperVee motor is not even warm. Good to see the cooling jacket is doing its job !! - I hear allot of complaints about the stock water jacket for the supervee but l have never had any issues with it.

I am really at a loss as to why the Mogli motor and batteries are getting extremely hot.

[ReddyWatts]

You might want to remeasure your strut to drive dog gap. It looks like 1 mm or less.

How many amps is it using?

[Eodman]

May I suggest you swap out props with your supervee and see if it still gets hot!

[Bill-SOCAL]

I think that 8 or more minutes is a VERY long run, especially if you are running aggressively. I never ran my SV more than 5 minutes with NiMHs (same ones you are using) and even then I had some pretty high temps.

The longer you run, the more heat you will generate. For sport running I keep it to no more than 5 to 6 minutes. In race trim I expect no more than 2 to 3 minutes.

Sadly, if you want to run for a really long time a gas boat (gasoline, not nitro) is the best way to do that.

[GregS]

What doesn't make total sense is that the ESC is cool. If the cause of the heat was excessive amps due to binding, over-propping etc you would think the ESC would also be hot. Maybe it is simply the long run time and the ESC stands up better than the other components.

[Doby]

May I suggest you swap out props with your supervee and see if it still gets hot!

I have to agree with Eodman. Try the SV Prop.
I have used that combo on my SV27, BJ26 and 1/12 Llumar with no problems.

Just to prove something to myself last fall, on my last run of my SV for the season I ran 14 packs (combinations of 6cells, 7cells and 2S LiPos) in a row,,,with just enough time to change packs in between runs. Air temp was in the low 50's and after the 7 runs, only the batteries were slightly warm. The motor and controller were cool.

To me it sounds like you might be over propped for what the batteries can take.
LiPos like to be warm for best performance.
A lot of NiMh have been dying around our club here this season. I have had 8 cells die last season alone.

[steveo]

i would have to say the runtime is the cause imo, i used to run my stuff real long and both the motor batts would come back real hot, just cut the runtime in half and see whats happens

[Fade2Gray]

Hi Everyone,

Thank you for all of your feedback. l will take that onboard.

For the record, my SuperVee prop is a M440, l will swap this around but l don't think this will make any difference. I might put the stock SuperVee prop on the Mogli and see what that does.

The gap between the strut and drive as pictured is less than the 3mm that l quoted which l had changed to see if it would maske any difference which it didn't. I will move this back having a 3-4mm gap.

I will shorten the runtime to see what happens although its little annoying brining the boat back in halftime when it is still peforming really well on the water.

Thanks again everyone..

[ReddyWatts]

Just another thought. The water tube on the back of the boat could be kinking and restricting the water flow when it is running WO from the airflow over the hull. Might shorten it or move it to the other side of the strut.

Do you have an infrared temperature meter to see exactly how hot the motor is getting?

[Fade2Gray]

Just another thought. The water tube on the back of the boat could be kinking and restricting the water flow when it is running WO from the airflow over the hull. Might shorten it or move it to the other side of the strut.

Do you have an infrared temperture meter to see exactly how hot the motor is getting?

I don't believe the water tube is kinded as l am getting a nice constant water stream from the water outlet. Unfortunatly l don't have a temperature meter, this might my next tool l will buy.