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[Purgatory]

Hi Guys
being very new to Boats/ RC - can I ask the following -
I have a Futaba Attack 40MHz system.
My present boat build will have 2 x 600 motors (operating on 12v - in Parallel, with the wiring done to suit contra rotation) and I wish to obtain a suitable esc with fwd/rev capability etc.
What amp rating should I ideally be considering? also what make/model might be the way to go. Being a pensioner, funds do not extend to the higher priced items!!
Would be grateful to receive any info from the more experienced people out there

[tjones27]

Hi,
if you try this website http://www.action-electronics.co.uk/speed.php they do superb speed controllers that arent very expensive at all and they provide excellent after care.
if you wired both motors in parallel and used maybe the P80 ESC. someone may advise something different. but if you email Action with your intentions they will advise you on the best ESC. the ESc will also depend on what size prop you will be using as that will change the current drawn from the motors.

hope this helps.

Regards Tj

[Roadrunner]

Depending if you want independent drive each motor will require at least a 15amp esc each which you can wire up through your channels on the transmitter in a tank steering arangemnt, or use a mixer unit between the two esc's to have both controlled by a single throttle, if purchasing a non ACTion set of esc's be sure to remove the BEC (battery eliminator circuit) from one of the esc's as you only need one to power the esc and servo's, both putting in 5-6v will kill your receiver. ( that's the centrer red wire , on the esc plug which goes into the Receiver)

However I would highly recommend the ACTion P94 twin 20Amp esc and Mixer unit, £78 bargain (and is suitable for your needs as you stated)  and the service is 2nd to non, he also does a power distribution board p102-3 so you can power lights and other functions from the same battery's , parallel boards for your battery's and other items that may be of interest depending on the model you have, triple or quad screws, bow thruster, etc.... he caters for all! 

[triumphjon]

providing you dont want independant control of your motors its possible to wire both motors up to a single controller , my own motor cruiser has twin motors , controlled with a single electronize esc , red cable to one of the motors , black to the other motor and a bridging wire across the other two motor terminals . what part of the city are you in ?

[Purgatory]

Thanks everyone for your excellent input - will give this some further thought.
 Re your comment triumphjon, you are suggesting that I run the motors in series -I did indicate I would run them in parallel - (this follows previous advice from forum members)

Slight possible change, because the motors are fairly high speed (RPM) - I could consider running the system on a 6v supply to take the unrealistic speed down a peg. Boat is twin motored - 54" long, with 2 x 5 bladed 50mm screws. (To contra rotate)
All suggestions welcome, and I will contact action as suggested by a member in previous post.

[Roadrunner]

You can wire the motors to one esc in parallel with no problems, ( as long as it can take both motors at stall current so 2 600's would be best suited with a 30a esc) its also the best way, series reduces the power to the last motor, remember how lights in series work first bright, 2nd dimmer and so forth.... same effect with motors most or a lot of the currents power is used by the first, the second in the circuit is using the wasted or return current so less power.

Im not saying you can't do it like that if you want but its best to stick in parallel so the motors had the chance to run the same.

If you want a single 30amp esc you can try here....  http://www.electronize.co.uk/model_electronics_frames.htm looking for the FR30HX Microprocessor Speed Controller which is rated for 30A, the aslo do larger at 40a and smaller at 15A. prices around the £30 mark.

[RaaArtyGunner]

RR, Can you or any one please elaborate.
Am bearing in mind, if I understood correctly, the comment on another thread, that it is from the negative terminal that the current flows from, which would mean, the motor connected via negative lead would be 'first'.
Also if have two 6 volt motors and only a 12 volt battery, then by connecting the motors in series, they should be able to run as each would receive 6 volts, yes/no??
Needless to say I am not proficient in the black arts

[Roadrunner]

RR, Can you or any one please elaborate.
Am bearing in mind, if I understood correctly, the comment on another thread, that it is from the negative terminal that the current flows from, which would mean, the motor connected via negative lead would be 'first'.
Also if have two 6 volt motors and only a 12 volt battery, then by connecting the motors in series, they should be able to run as each would receive 6 volts, yes/no??
Needless to say I am not proficient in the black arts

ok i'll try...

The current flows ( in dc motors , not brushless) from the positive to the negative (red to black) now in the case of motors being used in series the first motor takes a lot of the main power it be either 6v or 12, the discard power/ waste is then passed straight into the next motor in series via the negative output of the first motor and into the 2nd motors positive the out of 2nd motors negative to the battery ,this creates less power on the 2nd motor then the first regardless of the voltage.

Now if connecting in parallel which means both positives and negatives on each motor are directly linked to the esc terminals ( not through each other) they both have equal share of the power regardless if its 6 or 12v.

There is no split voltage in series one motor can't take 12v and then give the other 6 it takes 12 and gives the other maybe 2-4v at best which is the waste.

hopefully this makes a bit more sense.

If its easier i will draw up a diagram for you which could explain it better then me wording it. Let me know and i will crack on with that 

[Roadrunner]

OK drew up two diagrams the first is motors in series the 2nd is motors in parallel, i have drew them up using only a single esc, as using two would make both of these redundant as each motor has its own power control.

They are basic diagrams and I have 'guerstimated' the input of the 2nd motor receives in series but it is reduced either way, By how much i dont know ( i've never wired up motors that way but lights i have) but the principle is correct.

[Roadrunner]

The best way to find out the voltage going through the 2nd motor would be to wire up two motors, take your multimeter and see what voltage is going through the first motor is should be at 11-12v ( is using a 12v battery ) then while its running put the multimeter on the terminals of the 2nd motor and you will see the reduction in power that motor is getting.

Even if its 50% on the 2nd that would mean ... the first motor is running at 12v the 2nd is running at 6v meaning the fist motor is twice the power of the 2nd.

ha only took me 3 posts to explain it.... brains not working today...

[dreadnought72]

ok i'll try...

 

I have many problems with the above explanation.

Conventional current is defined as flowing from positive to negative, but we know it's really negatively charged electrons in the metal flowing from negative to positive. This makes your "first motor"/"second motor" concept simply not true.

The speed of electrons is really slow - only 1m per hour or so - so we might think one motor may "lead" another on any circuit. But the propagation of potential difference is really fast - nearly the speed of light. In reality, once the switch is thrown, the PD exists across all the components virtually instantaneously.

The issue, with two motors in series, is that if they are not precisely matched pairs, the first one to start up will produce (as all motors do) a back EMF which will affect the amount of current to second one.

Ummm...I think.  

Andy

[Roadrunner]

Well.. hopefully someone with better technical electrical knowledge can correct the posts I've always used motors in parallel as I've never seen a need to do them in series, lighting is a different matter (although the same principle)  I've done those in series for the effect of the first few being brighter and they dim out towards the end on projects (not just boats, model housing etc) I would have though my layman's explanation would give you the principle idea towards series connections and parallel?

[ACTion]

Never mind the theory, guys. Just don't connect motors in series - it's a pack of troubles waiting to happen.
Did no-one else spot that this chap is running 5-blade 50mm props on 600 motors? I hope they're geared down or they will be very much overloaded.
DM

[Roadrunner]

I noticed, just didn't say anything

[DickyD]

I noticed, just didn't say anything

Yeah right, when did you not say anything ? 

[malcolmfrary]

If the motors are identical, in series, they both take the same current.  Effectively, they both use the same voltage, which, as they are identical, is half the supply each.  If one of the motors is more heavily loade (stiffer bearings etc) it will lose some impedance, drop the voltage across itself, leave a bit more for its mate, and its mate, now having more power to play with, will work harder.  Like Dave says, a set of problems and heartache waiting to happen.
As for current flow theory, just stick with the old water analogy, with positive being higher, and the water running downhill.  Worked well for me for thirty-odd years and saved a lot of confusion when sorting diagrams.  If you can trace a path from + to -, without either going back on yourself or taking a short cut, you have a circuit.  If it goes through the components intended, probably a good circuit.

[Roadrunner]

Yeah right, when did you not say anything ? 

On your posts normally Dicky .. ''in one ear out the other'' i think is the phrase better suited. But funny that how yet again your posting stupid comments after mine and normally aimed at me,(i said that to you only 24 hours or so ago!) I'm sure your like a little lost gremlin that has to follow me about.. getting worried i might have a forum stalker... either that or your so bored you have to attempt to belittle people at every turn.

If you nothing positive to add to the post why not simple 'don't post!' before you get banned again 

[RaaArtyGunner]

If the motors are identical, in series, they both take the same current.  Effectively, they both use the same voltage, which, as they are identical, is half the supply each.  If one of the motors is more heavily loaded (stiffer bearings etc) it will lose some impedance, drop the voltage across itself, leave a bit more for its mate, and its mate, now having more power to play with, will work harder.  Like Dave says, a set of problems and heartache waiting to happen.[/b]As for current flow theory, just stick with the old water analogy, with positive being higher, and the water running downhill.  Worked well for me for thirty-odd years and saved a lot of confusion when sorting diagrams.  If you can trace a path from + to -, without either going back on yourself or taking a short cut, you have a circuit.  If it goes through the components intended, probably a good circuit.

That now clears up a lot of issues, as for me, no matter how finicky you are nor how good the motors some stiffness will occur.
Have a kit with manufacturers diagram to wire the 2 motors in series.
Parallel it is.
 

[Purgatory]

Have been in touch with Dave at Action as advised - (good move  )
Have decided to go down in prop size to 35mm 4 bladed, replace the Johnson 600's with Actions 555's
Can then use the P80. Running the motors in parallel
Thanks to everyone for your input (did I detect a little hijacking taking place in there ?
PS, anyone want 2 unused 600's ??????
Cheers