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Author Topic: Graupner 720 BB.  (Read 5203 times)

packy46

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Graupner 720 BB.
« on: November 19, 2009, 12:42:24 am »

Hi Gents:
Would someone be kind enough to tell me how many "turns" a Graupner 720 BB has so I can get a pair of decent
ESC's.
I found the specs in a post link but need the turns.
Thanks
Tim
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Andy K

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Re: Graupner 720 BB.
« Reply #1 on: November 19, 2009, 08:03:14 am »

I presume that you mean the Graupner 720 BB Torque.
No Load Current = 0.75A / Current at Max efficiency = 3A / Stall Current = 13.5A.
Base on these figures a 10A speed controller protected by a 7.5A Fuse should do the trick I would think.
I have 2 of these motors protected with 7.5A fuses and I have had no problems as for a speed controller I used an Action P94 unit (mixer and speed controllers in one unit).

Andy
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Mankster

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Re: Graupner 720 BB.
« Reply #2 on: November 19, 2009, 09:07:33 am »

I dont know the answer and have never bothered to ask before, but how does the number of turn is a motor corelate with the choice of ESC? I would have thought that all that mattered was Volts and current draw. i do not that lower number of turn normally means a faster turning motor with higher amp draw. There are plenty of motors with no mention of the number of turns in the spec sheet.

HS93 (RIP)

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Re: Graupner 720 BB.
« Reply #3 on: November 19, 2009, 09:25:17 am »

quite a few speed controllers have a lower limit on motor turns the sea sprint is one, But it is mainly to stop you using very hot car motors that are very high amp draw they are high Resistance motors and the start current can be very high.graupner do not give out there motor speck for any of there motors as far as I know but the 720 is a soft motor and is not normally a problem with speed controllers.

Peter
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FullLeatherJacket

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Re: Graupner 720 BB.
« Reply #4 on: November 19, 2009, 10:01:47 am »

Unlike its similarly-named Speed 700 buddies, the 720 Torque has eight poles - which throws another spanner into the works viz a viz the relevance of comparing turns and wire gauge. It's a lazy big old pussycat with no sharp claws; smooth as silk but it packs a hefty shove on 12 volts. 'Nuff said.

I would hesitate to recommend any particular ESC..................unless forced to by the promise of a sale!!  8)

FLJ
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packy46

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Re: Graupner 720 BB.
« Reply #5 on: November 19, 2009, 02:47:04 pm »

Hello:
Thanks for the reply.
Most of the ESC,s that I have looked at do not say anything about "turns" some do....
Some just guote 700 motors.
Also they will say how many cells the batterys should have to run the ESC, I have SLA's , only one cell in a SLA..
All help appreciated.
Link specs for turns.
http://www.towerhobbies.com/products/novak/novm1840.html

Thanks
Tim
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HS93 (RIP)

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Re: Graupner 720 BB.
« Reply #6 on: November 19, 2009, 03:12:14 pm »

yep thats a car one



Peter
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FullLeatherJacket

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Re: Graupner 720 BB.
« Reply #7 on: November 19, 2009, 03:15:49 pm »

Tim
There are actually six 2v cells inside a 12v SLA battery.
720 is a twelve volt motor - that's one 12v SLA or two 6v SLAs in series or a ten-cell pack of NiMH/NiCADs.
The website you have found is for car speed controllers. I presume that by posting on a model boat forum you are not interested in cars - at least as far as this particular application is concerned.
Cars use much faster motors than a Speed 720BB Torque, and they are usually in a smaller 'can' and have only three poles. The number of turns is used as an indication of the speed of these motors - and hence the likely current drawn and the power capability of a suitable ESC - whereas the word "Torque" should give you a clue as to the prime purpose of a 720.
Hope this helps.
FLJ

HS93 beat me to it by seconds!
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packy46

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Re: Graupner 720 BB.
« Reply #8 on: November 19, 2009, 04:46:06 pm »

Hey All.
Thanks again for the replies, OK now I understand, and yes, FLJ this is a boat application as you thought.
This really does take care of the ESC/Battery situation.
Thanks
Tim
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