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[hobbyman]

Hi all you leckies
If you run two 12v motors in series off a 12 v batt , do you get reduced speed  = to two 6 vlts per motor or there abouts ,excuse the question ,i'm a chippie ,

[FullLeatherJacket]

Yes.

[Ghost in the shell]

Hi all you leckies
If you run two 12v motors in series off a 12 v batt , do you get reduced speed  = to two 6 vlts per motor or there abouts ,excuse the question ,i'm a chippie ,

the other way is to wire them PARRALLEL, wiring both the live wires together and both the negative wires together so that the two leads form a Y the bottom prong of the y goes to the esc, the end two prongs go to the live or neg feeds.  be careful to reverse the polarity of one of the motors to get the motors counter rotating

[Faraday's Cage]

Hobbyman,

I don't confess to know the theory but practically, if you connect the motors in seriers they will both run as long as the loading in exactly the same but with a very much reduced torque. I have 2 motors which I cannot stop with my fingers on 6volt. But both will stop with ease if wired in series across 12 volts. Also if loading is not equal then the heavier loaded motor will stall and the other motor will run as if on 12 volts.

Why do you need to connect them in series ?Are they 6 volts motors running on a 12 volt drive battery ?

Terry.

[Welsh_Druid]

OK folks  - I got involved in this in private. The two motors are wired in parallel on 12 volts. The question was - the boat goes too fast on 12 volts so if the motors are wired in series will they get 6 volts each and thus make the boat go slower ?.

My reaction, (after saying change the battery to 6volt or dont push the throttle too hard  ) was - the first motor will get 12volts and the second will get slightly less as there will be a voltage drop across the first motor -  but I'm not too good on electrical theory so- ask on the forum.

Am I right or wrong ?

Don 

[DickyD]

Not to sure about motors but if you have the old christmas tree lights which were wired in series 80 lamps were only 3v each ie. 3 X 80 =240v  :-\

[sweeper]

Welsh_Druid,
A short answer to your question, the only way you could apply 12V to each motor would be to connect them in parallel.
In the configuration you are considering the voltage would be divided between the motors. The exact values of voltages will depend on a number of factors.
Without further information on the motors, I will leave the reply at that.

If slow(er) speed is required without the constraint of limiting throttle movement, would finer pitch props not be an easier answer?
Only my thoughts...
 

[DickyD]

I changed my prop on my PT boat to a smaller finer pitch prop.
Result, motor stopped blowing fuses and cooled down, made no difference to the speed.

Best bet is to wire in parallel and use a lower voltage battery. If I go from 9.6v to 6.0v in my twin motor Scheutze it slows it a little.

[cbr900]

For the cost of a six volt battery, would that not simplify the problem...............

Roy

[Martin (Admin)]

Also - http://www.modelboatmayhem.co.uk/Common/Electrics/Twin_motors.htm

[DickyD]

That doesn't help either Martin.

Dammit !! Now I'll be deleted again I suppose, rats !!  :-\ :'(

[Welsh_Druid]

For the cost of a six volt battery, would that not simplify the problem...............

Roy

Yes of course it would and I understand thats the way he is sorting it out (its not Hobbyman btw - just one of our relatives ) BUT  we won't learn anything that way will we? 

Thats whats so good about this forum - we can all learn something if we ask a question - OK maybe some of the posts are not quite as enlightening as others but somewhere out there is the truth !!!

Don B.

P.S. I gave him the 12volt battery in the first place 

[Martin (Admin)]

As FLJ says; "Yes".

As I understand it....
Two motors in series.
Motors each get 6v and therefore halves the current ie. half the power (usually 1/3 or 1/4 mechanical power in practice.)

Two motors in parallel:
Each motor gets 12v and the current doubles (if the battery is capable, if not the voltage drops)


Yes try the motors in series, can't see it should be too hard to experiment using a chocolate block connector.
Also try different size props and pitches.


http://en.wikipedia.org/wiki/Series_and_parallel_circuits

[DickyD]

That'll make it your fault then DonB.  :laugh:
Have you tried wiring it in series to see what happens. [ I know, daft bl**dy qestion }

[Welsh_Druid]

That'll make it your fault then DonB.  :laugh:
Have you tried wiring it in series to see what happens. [ I know, daft bl**dy qestion }

Well I was wrong  as I said, you learn things on this forum.   Tried it ? - well its complicated - The owner of the boat is Hobbymans brother who in turn is the partner of my daughter but we all live a long way apart  :(  So I guess he will try it and see what happens. Me ? - well I just stick in the biggest motor I can and run it on anything from 6 to 24 volts  - they never go fast enough anyway so I usually just up the voltage till they can cope with the conditions on our lake. 

Don B.

[malcolmfrary]

I've never been a fan of motors in series because there are so many variables which never seem to cancel out.  If both motors are identical, meaning identical performance at all speeds in both directions, and they bot have identical mechanical loads, they will split the voltage equally between them, producing equal speed.  Any variation, and the difference will be exaggerated, usually leading to a pronounced tendency to turn one way or the other.  A parallel arrangement is not as prone to this as the difference is just....the difference.

[hobbyman]

Hi All
I certainly opened a can of worms with that one chkl ,Yes i did try two motors myself later and it did reduce the speed of both ,i was just suggesting an economical way to reduce the speed of the boat ,and find out something for the future too in case i need it myself , thanks for all your help ,i hope others found it usefull too ,incidently to the americans ,a chippie is a wood worker ,
                                                                                                                                     Chris

[FullLeatherJacket]

Chris

Keep it simple. Two motors = two circuits = two ESCs = two batteries etc. Two Tx sticks as well, if you like. Makes balancing and controlling them easier and fault-finding MUCH easier. Like Big Don says, if it's going too fast then use the throttle.

I sometimes wonder why we put so much effort into making speed controllers "soft-start" and fully proportional when a lot of folk spend most of their sailing time trying to push the stick through the top of the Tx case.

Funny old world, ain't it?

FLJ 

[Colin Bishop]

I sometimes wonder why we put so much effort into making speed controllers "soft-start" and fully proportional when a lot of folk spend most of their sailing time trying to push the stick through the top of the Tx case.

Because some of us like to finesse our manoeuvres....

[tolnedra]

Dave

Don't you dare to alter your fine tuning ESC's! For scale steering comps a gentle touch is much more appropriate, I have no desire to charge around the lake, swamping everything in range. I gave up FE many years ago, having got bored with the same "M" shaped course, week in and week out. Give me variety every time!

Danny