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Neptune mod, or late to the party.

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Re: Neptune mod, or late to the party.

Postby JWLaRue » Tue Feb 25, 2014 5:27 pm

salmon wrote:It is a prop that Bob from rc-sub.com put on when he owned it. <...> So, should I back this prop off and get a 6 blade prop that TT sells?

I would definitely try that as a next step!

-Jeff
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Re: Neptune mod, or late to the party.

Postby salmon » Tue Feb 25, 2014 5:29 pm

For a test (and to spoil my son) I will order the prop and see. Then we can work on other ideas if the problem still occurs.
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Re: Neptune mod, or late to the party.

Postby JWLaRue » Tue Feb 25, 2014 5:36 pm

Yea, the more I think about it, the more I think that the prop may be the problem. I had a similar issue with my ProBoat PT boat. I replaced the stock props with some brass ones that were slightly larger and had a more aggressive pitch. This resulted in my motors overheating and the ESC cutting out. When I went back to the stock props, everything was fine.

So going back to the stock prop would be an easy/quick test.

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Re: Neptune mod, or late to the party.

Postby Sub culture » Tue Feb 25, 2014 5:56 pm

My observations were based on seeing Neptunes working with both standard and scimitar props. The replacement prop does improve speed, but the boat still looked a bit of a slouch to me.

The prop shop props I linked to earlier give considerably more pitch and blade area than the original, and looks more appropriate I think.

Or you could have a go at making a prop to similar design. I would be very surprised if that prop is loading the motor, assuming it's the standard motor of course. I'd get the ammeter and test.
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Re: Neptune mod, or late to the party.

Postby Ober Freak » Tue Feb 25, 2014 6:27 pm

That prop looks like the stock ones from Robbe's U-47 kit or a smaller one of the Seawolf (50mm) that I own.
I drive them with 10A or 16A fuse (or no fuse? on the Seawolf)) and never had any problems kicking them or overheating the ESC (Robbe Rokraft 120)

Marco

PS: dont't have the subs here to get a closer look.
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Re: Neptune mod, or late to the party.

Postby Bigdave » Tue Feb 25, 2014 7:02 pm

Just because a fuse is blowing now does not mean the motor is overloaded or overheating.
It means the fuse is too small for the prop and motor combination.
TT purposely made the stock prop smaller to gain more battery run time.
The larger prop you are running now is just more in the power range the stock motor should be in.
The ESC is total overkill at 170 amps max.
Even considering they are Chinese amps it is still impressive. :wink:
The week link is now the mismatched fuse.
The scimitar prop is better but we have run it side by side with a modified Rabosche prop and the Rabosche sub just walks away from the TT scimitar.
Using the stock fuse too.
But that is what makes the hobby challenging. No right or wrong way to do it.
Just your way as long as it works. :mrgreen: BD.
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Re: Neptune mod, or late to the party.

Postby Bigdave » Tue Feb 25, 2014 10:25 pm

I installed the ESC today for the brushless motor.
It just fit. :shock:
It is a honker! But the price was right and it is F/R with no brake.
(Hard to find) :roll:
I had to move the breakout board to make room on the tech rack partition.
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Re: Neptune mod, or late to the party.

Postby Bigdave » Wed Feb 26, 2014 8:31 am

BTW I will not be using the water cooling.
The motor should only draw 15 amps max.

Here is a photo of one of the LED units I mounted to the tech rack rail.
It is just a simple system.
Green on the right side, red on the left, and bright white in the front.
With the switch unit I have I can change from flashing to on always for the red/green, and white.
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Re: Neptune mod, or late to the party.

Postby salmon » Wed Feb 26, 2014 9:23 am

Dave, brushless is still new to me. I have read up on it, but until I get one in my hands it won't completely sink in. What does the brake function do and why do you not want it in there?

It will be fun to see those lights running, very cool. When are you going to be able to test your system out?
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Re: Neptune mod, or late to the party.

Postby Sub culture » Wed Feb 26, 2014 11:49 am

You get a brake on brushed ESC's too. Basically it shorts the windings on the motor to slow it down. Of use on model cars really.

Many brushless ESC's are programmable and allow you to switch the brake off if you don't want it.
'Why are you staring at an empty pond?'

Want to dive your boat in crystal clear water? Then you had better Dive-in- http://www.diveintomodelsubmarines.co.uk
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Re: Neptune mod, or late to the party.

Postby Bigdave » Wed Feb 26, 2014 12:57 pm

Some are but most aren't.
But as you said Andy most are set for cars and not boats.
Here is one sinario.
Some idiot pulls out in front of you on the water and you need to reverse quickly.
You pull back on the stick and it has to spend time in brake before it will enter reverse.
A few seconds can seem like an eternity. :cry: :oops:
Not that I have ever done this. :lol:
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Re: Neptune mod, or late to the party.

Postby Bigdave » Wed Feb 26, 2014 1:05 pm

O!
I just tested the system out in the laundry tub.
I am pulling 15.8 amps at full throttle.
And pushing a heck of a lot of water.
Right where I wanted to be for the motor.
I will try the sub in the pool in March at the YMCA funrun.
You had asked how to measure the power being used by the motor.
I use a watt meter made by Astroflight.
Other companies sell them too.
It is connected between the battery and the ESC.
The read out gives you the input voltage, amps, watts, and amps used.
Very useful tool.
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Re: Neptune mod, or late to the party.

Postby Bigdave » Wed Feb 26, 2014 1:13 pm

O!
One more thing.
I connected the old Venom motor to the watt meter to see how much current it would draw with no load.
Well. :roll: :cry:
It was 35 amps and after one second smoke started to come from the windings.
It is not what you call a well motor. :mrgreen:

BTW Here is a photo of the new brushless motor in the sub. 1/3 the size of the stock motor and 3 times the power.

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Re: Neptune mod, or late to the party.

Postby salmon » Fri Feb 28, 2014 2:12 pm

I got the fuse, actually a 10 and 15 amp. Using the 10 amp I tested the electronics and all seems to work o.k.
Is there any maintenance that I can do or should do for the brushed motor that comes with the Neptune? oil?
Thank you!
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Re: Neptune mod, or late to the party.

Postby Sub culture » Fri Feb 28, 2014 3:10 pm

A drop of light oil on the front and rear plain bearings doesn't hurt. Once a year should be perfectly adequate, unless it's doing some very heavy duty,

That's about it really. Not very easy or practical to clean the armature or mess with the brushes, not that a modestly powered motor like this should give much grief anyway.
'Why are you staring at an empty pond?'

Want to dive your boat in crystal clear water? Then you had better Dive-in- http://www.diveintomodelsubmarines.co.uk
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