Starting a Mogador Build - Drive question
Last Post 22 Apr 2011 03:17 PM by warspiteIRC. 28 Replies.
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Steve TyngUser is Offline
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04 Jan 2011 05:00 PM
I just purchased four 2.3AH 6.6v A123 LifePo4 packs. This should give me some flexibility in mounting and voltage.

Steve
RichelieuBBUser is Offline
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04 Jan 2011 05:09 PM
Sounds like the same packs I've eyed on Hobby King. heh.
Mike Mangus

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froggyfrenchmanUser is Offline
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05 Jan 2011 07:39 PM
I plan to run a pair of smallish motors in my Le Terrible. Probably with Dumus dog-bones.
That way if I lose a motor, I will still have some mobility.
The Frenchies are big enough, and heavy enough to carry the weight.
Mikey
Steve TyngUser is Offline
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10 Jan 2011 04:34 PM

Anybody have any thoughts on wiring dual (brushed) motors in series or parallel? Team Novak states that series configuration will give you more torque but a lower rpm, which sounds good for our application.

http://www.teamnovak.com/tech_info/How_to/dual_motors/index.html

Steve

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10 Jan 2011 06:41 PM
I run mine in parellel, preferring to keep full voltage to both motors versus splitting it between to series motor. Also, if one motor dies for some reason, at least I still have another motor that works.
Mike Mangus

Beware the French Revolution!
Operational:
HMS Erin DN
FN Richelieu BB
FN Verite PDN

Launched
Le Requin Xebec (AoS)

Under Construction:
FN Mogador DE
FN Gascogne BB (Treaty)
FN Bretagne (1/96) (delayed)

Mothballed:
FN Bearn CV
TugboatUser is Offline
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10 Jan 2011 07:00 PM

Although if you get mossed up and stall one motor, it is still drawing full voltage but with zero CEMF to resist current flow. Could burn out (or at least damage) a motor. In series, the still-running motor prevents the stalled motor from seeing max current. On the other hand, with brushless motors like Steve's using, the ESCs will either trip on overcurrent as they try to turn the stalled motor, or they'll fry themselves, sparing the motor haha. Thus far, my brushless ESCs seem to be quite adept at protecting themselves, so I'd say go parallel at the inputs to the ESCs from the battery, as that'll give each ESC more voltage to work with, which is a good thing. But it will have no direct effect on the motors' performance.

Battling: SMS Scharnhorst, SMS Baden Building: HMS KGV (Drives, pumps water, guns are in but not plumbed) MN Edgar Quinet (Hull done) Drydock/Mothballed: Rus Evstafi, DKM Lutzow, HMS Invincible Plus 20-odd other projects, according to my Boy Scouts who thoughtfully counted them for me.
Steve TyngUser is Offline
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11 Jan 2011 09:12 AM

Tug,

I've decided to try some brushed motors that look good and tested well instead of brushless.  The brushless motors may still be used just to see how they work.  May still use one of them for the pump.  The configuration will be two motors direct drive with one ESC.  I'll test series and parallel setups to see which gets the best acceleration once it's on the water.

Steve

 

Phill LoweUser is Offline
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22 Apr 2011 03:02 PM

My experience is that the Mogodor is a challenging build.  You need to think small and keep weight low in the hull.  I've got two 385 doing direct drive on the props.  The hull is quite tight and I'm not happy with this set up.  I'd rather go with a gear box and a single motor, I think a single 385 would work.  I stayed scale and have a pair of 4 blade 3/4 inch props.  These are not terribly efficient as you don't get much blade on a 3/4 inch prop and there is no advantage over a three blade prop.

My biggest problem is space, she has a very small amount of space and I wanted to seal the back deck so just getting to everything is a pain.  I have a palmer rock-the-boat regulator so she runs off a 16g co2 cylinder.

She is a fun ship to play with.

WCC Minister of Misinformation.
warspiteIRCUser is Offline
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22 Apr 2011 03:17 PM
Never, run drive motors in series!!!! The difference in internal resistance makes one run faster than the other and eventually only one will get almost all of the voltage drop.
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