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Author Topic: What size and sort of ESC should I use  (Read 167 times)

BlueWotsit

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What size and sort of ESC should I use
« on: May 03, 2019, 01:08:20 PM »

Have a small tugboat (about 22 inches long) which has a Graupner 720 BB torque motor already installed but no other gear


What sort of speed controller should I be looking at for this motor 2 x  6v batteries installed

thanks




OOPS just realised theres another forum MODS can you move this please
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malcolmfrary

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Re: What size and sort of ESC should I use
« Reply #1 on: May 03, 2019, 07:53:35 PM »

That is a lot of motor for a fairly small boat, but assuming a sensible prop, a Marine Viper 15 should be fine - a 25 if you need more safety margin.  Before getting an ESC I would first do an in-water test using a meter to get an idea of the current under load.  Or run through a selection of fuses to seek a value.  Are you planning on using the batteries in series or parallel?  The extra volts of series can make a difference, ruling out many of the fleabay escs which are not intended for 12 volts.

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BlueWotsit

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Re: What size and sort of ESC should I use
« Reply #2 on: May 04, 2019, 11:01:17 AM »

Hi - when i bought the boat the 2 batteries had been epoxied into the hull which is a pain - they are wired red to red, black to black if that helps


The inside of the Kort Nozzle is appx 4cm and the prop is just inside it all the way around


The motor mount is also epoxied in, I might be able to get the motor out but would it fit the mount is another question - what sort of motor might be an alternative if I can do this


thanks
Andrew




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DaveM

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Re: What size and sort of ESC should I use
« Reply #3 on: May 04, 2019, 11:44:01 AM »

Andrew
Do check the model in a bathtub first - 22" seems very small for carrying two 6v SLA batteries and a big motor. Also charge up the batteries and check the voltage with the motor running. SLA's need regular topping-up and will fail if this hasn't been carried out.
While agreeing with Malcom about the power of a 720 Torque, I reckon that @ 6v - which is the way your batteries have been wired - it should be OK with a 3 or 4-blade prop to fit inside that Kort. After all there's nothing that says you have to run at full throttle all the time. The motor is a low-drain type and a 15A ESC will be more than adequate. MTroniks are a popular type; they will work at 6v and are offered with a warranty service which you'd be unlikely to get from a Far-East supplier.
DaveM
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BlueWotsit

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Re: What size and sort of ESC should I use
« Reply #4 on: May 04, 2019, 12:24:16 PM »

Hi Dave - I've been told its a Springer (?) tug, checking the measurement without the buffers which are on the front the hull length is nearer 19 inches, 9 inches wide and 8 inches deep.


In the bath, with the batteries and all radio gear inside it is balanced well right on the waterline. I charged the batteries before water testing which I did to check no leaks or anything, and they are in good state - they look quite new to me.


When I last was boating some 8 or 9 years ago, I tended to use Mtroniks then so good to hear they are still going - agree with what you say about the Far East ones


Will check the voltage next time the bath is filled up  :-))
cheers
Andrew



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Netleyned

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Re: What size and sort of ESC should I use
« Reply #5 on: May 04, 2019, 12:49:21 PM »

If it's a Springer, then 2  6v SLA's will be needed for ballast and will give you long run time.
Springers are 18 x9 inches to comply with the US of A rules but there are lots of clones with slightly different dimensions. 540 motor and no kort are
also rules. Mine has a 540 motor and a steerable kort with a 4 blade kort prop and an extra pound of lead for ballast over the 2 x 4.5 Ah 6v lead acids.
Keep a gentle hand on the throttle stick as they want to be submarines and dive if pushed too fast. Mine is called International Rescue at the lake as it has about 300 rescues since 2012.
Ned
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BlueWotsit

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Re: What size and sort of ESC should I use
« Reply #6 on: May 04, 2019, 01:23:19 PM »

thanks for the info Ned
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Netleyned

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Re: What size and sort of ESC should I use
« Reply #7 on: May 04, 2019, 01:38:14 PM »

Replying to the original query, I have a 20 amp MTronics esc in mine. No problems over 5+ years
hard work at the lake.
Ned
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Up Spirits  Stand fast the Holy Ghost.
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