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Max AMP draw for Pittman 12volt motor?

R/C Submarine modelers

Max AMP draw for Pittman 12volt motor?

Postby Warpatroller » Sat Feb 21, 2009 5:39 pm

I have a NOS 1994 vintage Pittman 12volt motor with a 40mm diameter can. The motor part number is 9513B397. It will be set up as direct drive turning a 44mm diameter brass 3-blade propeller. This is to power a vintage 32nd Parallel XXIII model.

I have been unable to find any specs on this motor to figure out what its maximum AMP current draw is. I want to select an appropriate Mtroniks Viper ESC to use with this motor. My guess is that it will draw more current than the MicroViper Marine10 (10 AMP) is capable of handling.

Other ESC controllers in the Mtroniks line up have the following max AMP limits:

Marine15 (15 AMP)
Marine20 (20 AMP)
Marine25 (25 AMP)
Marine40 (40 AMP)

Can anyone confirm that my Pittman motor will require a higher than 10 AMP controller and if so what AMP limit would be safe to run with the motor and setup that I described above, or would it just be safest to use the Marine40 with it?

Thanks,

Steve
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Postby Warpatroller » Sat Feb 21, 2009 5:51 pm

I forgot to mention that the stock system battery voltage for the boat is 9.6volts. I might increase it to 12volts, maybe. So the max AMP draw would be based on the motor receiving 9.6volts instead of 12volts. But I guess it is still possible that even with 9.6volts the 10AMP controller may be insufficient.
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Postby Bigdave » Sat Feb 21, 2009 6:15 pm

One of the best things about a Pittman motor is its low current draw.
I would be really supprised if that combo drew more than 2-3 amps.
As long as the Viper-10 can handle the 9.6 -12 volts is should be fine. BD.
BTW- Jim Butt has more experience running the Pittmans. Maybe he can chime in if he see's this.
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Postby Warpatroller » Sat Feb 21, 2009 9:44 pm

Thanks Dave. It is good to know that those Pittman motors function with a low current draw. Sounds like they are quite efficient in operation. The Viper Marine10 has a voltage range of 4.8 to 12volts, so it looks like I might be able to use it after all.

I'll wait until I can get a few more confirmations though before I decide on which ESC to purchase.

Steve
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Postby Chuck Chesney » Sun Feb 22, 2009 11:13 am

I have been running Pittman, and later the Dumas/Pittman motors, since the 1960's. They are very low current draw, like Dave Welch says, and are built as solid as a brick oven. I have used them on several surface boats and a submarine, in both the 6v and 12v versions,. I believe that the maximum current draw, which occurs on the 6v unit, is about 3-4amps, the 12v maximum is about 2-3 amps.
The motors are low speed/low draw, which makes them ideal for direct drive in a model boat.
Chuck

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Postby Warpatroller » Sun Feb 22, 2009 5:01 pm

Thanks for your input Chuck. I agree with your statement about the Pittman being built like a brick oven, as it did feel VERY solidly built when I held it in my hands and examined it.

This 32nd Parallel kit really seems to be well thought out and engineered for its time. As I read more and more of the manual I become more impressed with the thought that went into the design. They were even thinking about reducing motor vibration, and have included rubber vibration isolation mounts for use when installing the Pittman motor within the pressure hull. Most current WTC setups I have seen on here, have the drive motors either rigidly glued on or screwed into their motor bulkheads.

In general, in regard to noise and vibration control, RC submarines are totally unlike their full size counterparts. RC subs are generally ANYTHING but quiet in their underwater operation. I think it would be impressive to design a very quiet and near silent running RC sub, which could barely be heard at all in the water. My father worked as a noise and vibration specialist for the US Navy. He worked on keeping our submarines and surface ships running as quiet as they could during the 70s and 80s. Now though, do to his current old age and poor health, he probably wouldn't be of too much help to me with such a project.

Steve
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Postby Skip Asay » Mon Feb 23, 2009 12:22 pm

According to a very old Pittman datasheet I have, the 12 volt 9513 series motors are rated at 5600 RPMs at no load with 5 1/2 amps current draw at stall. That means that virtually any speed control you can get your hands on will work.

Since the beginning of time (for me, at any rate), I have been a firm believer in Pittman motors. The best example I can give is my now 28 1/2 year old 1/24 Type XXIII. That boat uses five 2 volt 5 aH sealed lead acid cells and a 6 volt Pittman motor. Now I realize that some of you will notice I'm running a 6 volt motor on 10 volts but, with an 8.2:1 toothed belt drive, max current draw is only ONE AMP. Obviously, there have been no ill effects.

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Postby Warpatroller » Mon Feb 23, 2009 4:20 pm

Thanks Skip, I think this question has now been conclusively answered. And by the Godfather no less!

That is a lot of reduction 8.2:1, most guys seem to run around 3:1 or 4:1 in their subs (from what I've seen or here). I would think even at full throttle your boat would still move along at a scale speed with that amount of reduction. Your run times must be very long with such a low current draw. You used a belt drive to eliminate gear noise and to possibly further reduce current draw?

I'm going to try the stock direct drive set up in mine, mostly to simplify the installation and so I don't have to purchase any new drivetrain hardware. Then if I find it not to my satisfaction, I can later implement a reduction system. What do you think about that?

Any chance you could post a photo of your XXIII? It would be nice to see what a 28+ year old boat looks like after all those years of service :D
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Postby Sub culture » Mon Feb 23, 2009 5:00 pm

Depends on the size and pitch of the prop. A 1/24th scale Type XXIII is going to have a fairly large prop.
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