How do I wire up my motors?

Hope somone can help me..

I am building a Duetschland class battleship, and am not sure how to wire it up right. I bought an ESC from fleebay but it keeps getting WAY TOO hot. What I'm wondering is how is it supposed to be wired? I am using two motors attached to the propellors & a 6V battery. How do I tell if my ESC is bad?

 

Hello,

First thing I would do is see what kind of amps your motors are drawing under load and how many amps you ESC can handle. I use the M-tronics marine 15 for my boats. I set up one marine 15 per motor. I like the redundancy. As for motor wiring, ill try in put in layman’s terms as all the tech speak tends to throw people off. Wire the + from one motor to the – of the other and visa versa. Then take a + and - lead of one of the motors to you ESC. ( if using one ESC) This should provide you with the counter rotation we look for. I would recommend two ESC , but that’s just how I do it.

I hope this helps,

Plato ( it’s all Greek to me) Avramides

 

There's a quick fix for that. Just get take a few holes below the boot and let in some water. If that's not enough, go visit Davey Jones. Your ESC will cool off REAL quick then =D

Seriously, what do you mean by "way too hot"? As in feels-warm hot, burn-your-hand hot, red-hot, or let-out-the-magic-smoke hot? If you ESC is bad, the motors will usually not respond to signals from your radio. Sometimes the wires will melt, and lots of smoke is also associated with ESC failure. Try testing the ESC with a single low-draw motor. If that's working fine, then the ESC itself is fine. If that's the case, you need to cut down on power draw or improve heat dissipation. gear down your motors, get more efficient motors, run one ESC per motor, or install water cooling.

PS: isn't the Deutschland considered a Heavy Cruiser, not a battleship?

 

There was a Deutschland class of battleship in WWI, obsolete even then:

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

That's probably not what he's got, though - I'd bet it's the more-familiar "pocket battleship" of WWII.

JM

 

i thought a "pocket Battleship" = battleship?

thanks for your help guys... i found out that the motors were drawing like 30+Amps! i think the motors are not rite. i will get another set on next week.

 

I'm still pretty new to this hobby, but what I got from others. This setup is pretty common. Remember that everyone does things a bit different.

Here is a sample of the wiring.

http://www.s-t-f.com/images/001_MAG.gif

 

Pocket Battleships was coined by the Western Press. They were in fact very large heavy cruisers. The main gun size of 11 inches gave them the term Pocket Battleships but were in fact large heavy cruisers.

 

Not necessarily. Putting them in series splits the voltage. Plus if one burns out both are dead. If one gets a higher resistance, it will take a higher percentage of the voltage perhaps putting it over its voltage rating.

Andy

 

I^2*R = I*(I*R) = I*V = P => power. Power makes heat. Not just current. If it was just current, power mosfets wouldn't work. They pass a lot of current, but have such a low R that they drop only a few milliVolts (or less), therefore can stay within heat tolerances.

 

Also, you can't have equal motor speed to current that way... Power does the work, not current.

Series wiring:
V = I * (R1 + R2)

A motor "requires" more current by lowering its resistance when it needs more torque to spin to the speed "requested" by the voltage. Don't believe me? Use a multimeter & try it!

As R1 goes down (stalled motor) the R2 would stay the same... Therefore current though the motors would be equal to whatever M2 is requesting, which would go up.

But since M1 has a very low R, (& V=IR) the voltage dropped over it would be nill; therefore (P=VI) power would be low; therefore it would NOT be able to create the torque to break the stall.

Think of it like this... What happens to a motors speed if you put a potentiometer in series with a motor? The pot takes its share of the voltage & lowers the amount of current that can flow through the circuit. Same thing is happening here with two motors.

 

Based on the resistences, motor Y is requesting more torque.

So

Motor Resistance Current Voltage drop
--X-----1ohm-------4A-----4V = 16W
--Y----0.5ohms-----4A-----2V = 8W
In the parallel-wired ship:
Motor Resistance Current Voltage drop
--X-----1ohm-------6A-----6V = 36W
--Y----0.5ohms-----12A-----6V = 72W


For the same hardware, it is obvious that a parallel system is more powerful (Watts is power, hence powerful); however it will suck down more current... hence is capable of eating through the stored charge in the batteries faster... But that is a different discussion.

ALSO, if you look... the motor that is requesting more power, is getting it in a parallel circuit... not the other way around.

 

Sorry for the bunch of replies... Not trying to put you down tuggy!

Your solution is good for lowering the current & power, therefore maintaining the wires & motors at a safe level. You should only wire motors in parallel if you KNOW that your speed control system &&&&&AND&&&& (I cannot stress this enough) your wires can support that kind of current!

1 AMP is enough to kill you several times over. The Alsace has clocked in at over 30Amps (with some VERY hungry motors)! I judge the Iowa will be able to (not that I will ever let it) pull nearer to 90Amps. That's enough to melt the batteries & me along with 'em. It is imparitive that I create the boat to be able to safely support that current or (more likely) safely fail away from that current (fuses, etc).

I've noticed a lot of skippers (especially Big Gun Boats) not paying attention to their current ratings. Then they wonder why their speed controller fails, their boat catches on fire... etc, etc. EVERYONE MUST pay attention to the one system that could truly kill you or destroy your multi-thousand dollar investment...

 

Ok not an engineer but I thought that in series one motor acts like a resistor. I found that wiring in series did not produce the kind of performance that wiring in parellel does. I also found that wiring in series cuts down on running time and reduces power unlike parellel. Now I have no mathematical formula here to debate but this is bassed on experince wiring more than 65 models the last 15 years and this is based on observations through trials and testing and rewiring . I have to agree with Scott on his view of series vs parellel. The way I see it if you want to slow your model down run you motors in series but beware one motor will be sucking more power than the other. If you want both motors to perform equally with power then run it in parellel. Parellel works great in my book.

 

No, not unhappy at all! I was afraid I might have piss'd you off! I rewrote the text about 20 times trying to remove emotion (or what could sound like emotion)


OK.. so our basic disagreement is that either power or current creates torque. We could look it up or let it go. I'll let the choice to you.

(BTW: Wiki has an good article)

Its not that you are wrong.. just incomplete. Power is defined as a measurement of work getting done (or more accurately the rate of which). Electric Power is created by combining Voltage and Current. In most situations talking about motors, the voltage is fixed at the time of interest so increasing current = increasing power.. thus increasing torque.

 

oooooohhhh... beeer.. Now that sounds like a good idea.

I got a message from the little woman saying she wanted me to pick up cheese & veggies on the way home. What I think actually happened is her message got scrambled, probably from a bismark with a large radar dish (sorry, I've been reading the canadian's posts again.. too funny) & what she actually meant was "beer".

I better bring home beer, so she isn't mad at me & I don't have to sleep on the couch again. OOH... Maybe there was something about chicken wings in that messsage tooo....

 

Until recently most of the MBG member have used on/off switches for speed controls. If properly setup a BigGun battleship should easily draw no more than 5 amps. I had 2 12 motors that I ran in my North Carolina (got them from BDE and can't remember the type). These 2 plus the pump pumping hard and electronics was somewhere in the 2-3 amp range (had a 5A fuse just in case). I had 12V 7 Ahr of battery that lasted 4 hours+ of battle before running out.

Once I switched to 6V 14 Amp Hour and 2 Wah ming motors (again from BDE) I never ran out off battery again.

So if someone is pulling 20+ amps on a biggun ship, there are problems somewhere.

Andy