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Author Topic: MTRONIKS VIPER 25 AND GRAUPNER SPEED 600  (Read 5533 times)

steamshed

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MTRONIKS VIPER 25 AND GRAUPNER SPEED 600
« on: July 21, 2011, 03:52:26 pm »

Hi Folks
Can anyone please tell me if these 2 are a good match
Regards
Mike
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Guy Bagley

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Re: MTRONIKS VIPER 25 AND GRAUPNER SPEED 600
« Reply #1 on: July 21, 2011, 04:23:58 pm »

it will depend on what prop you use, but i have a boat (a fast customs launch - 37 inch long )  with 2 x graupner speed 600 's in it and i use one mtroniks viper 25  for  control of both motors  and all is good,

props are not huge about 35- 40mm diameter  and power is from a 12 volt battery. i also have a 20 amp fuse in it and its never blown, - so i would say its a fair assumption you'll be ok so long as  your not stressing the hell out of the motor with a 90 mm prop !!!
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all in all its just another brick in the wall......

DickyD

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Re: MTRONIKS VIPER 25 AND GRAUPNER SPEED 600
« Reply #2 on: July 21, 2011, 04:25:09 pm »

There are several Graupner speed 600s

The 8.4v one Current drain when stalled 70 A

So you will need a speed controller in excess of 70A

Check which one you have first.

Then check stall drain on the table below.

http://homepage.ntlworld.com/edward.matthews/ddmbc_files/motors/graupner.htm
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Guy Bagley

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Re: MTRONIKS VIPER 25 AND GRAUPNER SPEED 600
« Reply #3 on: July 21, 2011, 04:28:08 pm »

good  point, ,

 my motors are the 7.2 volt versions,  when ran under load i was drawing nothing like 25 amps... and stall current was alot less than 70amps, if memory serves about 30 amps ???
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all in all its just another brick in the wall......

DickyD

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Re: MTRONIKS VIPER 25 AND GRAUPNER SPEED 600
« Reply #4 on: July 21, 2011, 04:33:37 pm »

good  point, ,

 my motors are the 7.2 volt versions,  when ran under load i was drawing nothing like 25 amps... and stall current was alot less than 70amps, if memory serves about 30 amps ???

The stall current on Graupners chart is about twice that Guy. :-))
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steamshed

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Re: MTRONIKS VIPER 25 AND GRAUPNER SPEED 600
« Reply #5 on: July 21, 2011, 04:47:12 pm »

Hi
Thanks for quick response Guy and DickyD
here's abit more info, Speed 600 7.2v current drain at max eff 12amps, 40 size prop 2 blade, 2  x 7.2v 4600 batteries using one of Dave's gizzmo's for parallel supply.
Boat is a Huntsman 31 fibreglass hull pretty light
Put it on the pond at Sherringham today, very small amount of throttle just to get the feel, which was ok, then slowly started to open up, did about 2 foot then just stopped.
Have check supply still 7.2v rudder works, but no output to motor despite ESC lights showing green for forward and red for reverse.
Now stuck unless I've done the ESC in, steam I understand, but this is me now trying to move into electric's Cheaper!!!
Mike
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DickyD

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Re: MTRONIKS VIPER 25 AND GRAUPNER SPEED 600
« Reply #6 on: July 21, 2011, 05:02:03 pm »

According to the Graupner chart the stall current for this motor is 85amps.

If this is right I would think you need a new speed controller.

Having said this, I had a PT boat that did the same as yours has just done but I had a fuse in the circuit and it blew that instead of the ESC.

Cured the problem by using smaller [35mm], 2 blade props with a very small pitch.

Worked for me. :-))
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Shipmate60

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Re: MTRONIKS VIPER 25 AND GRAUPNER SPEED 600
« Reply #7 on: July 21, 2011, 05:24:50 pm »

It is usual to protect the ESC with a fuse rated below that of the ESC rating.
If we all went by the stall currents then anything with a 540/550 would need in excess of 100 amps.

Bob
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steamshed

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Re: MTRONIKS VIPER 25 AND GRAUPNER SPEED 600
« Reply #8 on: July 21, 2011, 07:01:34 pm »

Hi
Thanks for all your info and advise, I'm still trying to get my head round this, I must confess in my hurry to get on the water I did omit the fuse  {:-{, I guess stalled current drawn is like locked rotor then I can understand the high current drawn, but as I was maybe max quarter throttle and Mtroniks say it has built short circuit protection and also motor stalls. oh well its a learning curve, next time the FUSE  :-))
Once again thanks all
Mike
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treeboa

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Re: MTRONIKS VIPER 25 AND GRAUPNER SPEED 600
« Reply #9 on: July 21, 2011, 11:57:56 pm »

Hi
Thanks for all your info and advise, I'm still trying to get my head round this, I must confess in my hurry to get on the water I did omit the fuse  {:-{, I guess stalled current drawn is like locked rotor then I can understand the high current drawn, but as I was maybe max quarter throttle and Mtroniks say it has built short circuit protection and also motor stalls. oh well its a learning curve, next time the FUSE  :-))
Once again thanks all
Mike

always the possibility its a faulty one, send it back and see what they say
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steamshed

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Re: MTRONIKS VIPER 25 AND GRAUPNER SPEED 600
« Reply #10 on: July 26, 2011, 06:42:08 pm »

Hi All
Spoke to Mtroniks Friday, they seem to think it could well be faulty, so have returned it as they requested, await their verdict
Cheers
Mike
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nick_75au

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Re: MTRONIKS VIPER 25 AND GRAUPNER SPEED 600
« Reply #11 on: July 27, 2011, 08:26:50 am »

Stalled current of a 7.2v Speed 600 is 85 amps, current at maximum efficiency is 12 amps, fuse for 20 amps and if you are drawing more than 20 amps the load is too high. 25 amp ESC will be fine. The Motor will burn out if it remains at stalled current for any period of time,.

Nick
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steamshed

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Re: MTRONIKS VIPER 25 AND GRAUPNER SPEED 600
« Reply #12 on: July 28, 2011, 06:35:45 pm »

Thanks for that Nick
A replacement arrived today from Mtroniks, good service
Mike
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