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[Coxn John]

Today my 20amp speed controllers fried all wiring to the motors AND the motors, im very lucky the whole boat didn't catch fire, severe cable melting took place,  please advise me.
New motors im fitting now are 6volt RS-550SH brushed motors
Battery power is 6volt 12amp/hour
What amp speed controllers do I need ?

[lordfortesque]

always fit fuses then you wont have that problem again.
mike.

[Umi_Ryuzuki]

What size propellers were you using?
 

[Coxn John]

What size fuse would you fit please ?
Im using 50mm props (which the motors previously had no problem with using mechanical power controllers)

[NFMike]

What size fuse would you fit please ?

The spec sheet I've found says they draw about 6A at max efficiency, could be a bit more if not best, say 10A.
Stall current is about 50A.
To be safe I guess you'd need a 50A controller (depends if it is specced as stall or running), but I'd use a 10 or at most 15A fuse (per motor).

[Coxn John]

Thankyou, i'll search for 2 x 50amp controllers, probably go for the 'Tornado' ones from Howes unless anyone has any suggestions re others

[Stavros]

Ok WHAT make was the speed controllers you were using.....Personlly I would NOT use the tornado esc's as it's chineese Amps that you are dealing with use  ACTion 20 amp ones obviously using fuses of 15amp
 
Dave

[Coxn John]

The ones I was using were 'RCmodelparts 20 amp'.
Im surprised you say use 20amp again Stavros, as it seems something was overloaded (to burn out wiring & motors) surely it was the controllers no ?

[Coxn John]

ACTion appear not to do one for my voltage with BEC, as space is at a premium I need BEC.

[jaymac]

I would get one of these find out what  amps you are pulling easy to fit then bung the boat in the bath. less than a tenner Paper readings dont apply to  our models http://www.4-max.co.uk/gt-mini-voltage-current-meter.htm
 

[Coxn John]

Thanks Jaymac, sensible idea, I will.

[jarvo]

Hi John


If you had no trouble up till today, is it posible you picked up some weed or line round the props?????


Had no problems with the Tornado ESC and the similar blue ones, but as Stavros said they are chinese amps. Only go back to the water after testing your current draw, 550's can be thursty beasts, but a 15 ah fuse should be more than adequate


Mark

[inertia]

John
As has been said it isn't speed controllers which fry wiring - it's the load on them. Don't dismiss ACTion ESCs because they don't have BEC. You could fit one of these pretty much anywhere and it will do the job better than any one fitted inside a speed controller  http://www.componentshop.co.uk/3a-max-5a-universal-battery-eliminator-circuit-ubec.html
DM

[spearfish99]

Just to state the obvious, fuses go between the battery and the ESC.
 

[Coxn John]

There was nothing round the props,
Iv ordered a 'current draw tester' as recommended -)
One more snag that's raised its head, many of the speed controllers are only 20% power in reverse, that's no good for this boat as its props are a matched pair, so left (port) prop is always in reverse, so im still searching for affordable speed controllers which will work....eeeee I hate modern technology, bring back mechanicals, Bobs Boards all is forgiven !

[cuppa]

Hi John

Rather than run one speed controller in reverse to achieve contra-rotating props could you not just switch the +ve and -ve wires on the relevant motor and then run both controllers in forward mode with the motors running in the desired direction of rotation?

[malcolmfrary]

If the ESCs survived the mellting of the wire to the motors, there is nothing wrong with the ESCs other than that they can probably handle a lot more current than they need to.  The wire needs to be heavier, or it will act as a fuse (which is a bit of weak wire that melts when you pass too much current through it).  If running two motors in parallel off one ESC, each motor needs its own fuse.  Otherwise, a fuse is only really needed between the battery and ESC.  Fuses are not really there to protect what they are feeding, they are there to protect what is supplying them, and, by preventing fires, what is surrounding them.  Most ESCs today incorporate some form of current limiting, so don't need any fusing between themselves and a single motor, but a high rated ESC might well be capable of supplying enough current to do damage in a fault situation.
If the motors got fried, and the system is running on the same voltage, there is something severely wrong with the mechanical setup causing the motors to stall, or go into a near stall condition when they will pull a lot more current.

[jaymac]

only 20% power in reverse, that's no good for this boat as its props are a matched pair, so left (port) prop is always in reverse, !

 May be wrong John but the fact the prop is handed and wired to run in  reverse to its neighbour methinks  does not  matter to the speed controller its sending out forward polarity to both
 

[Coxn John]

'cuppa'  I hadn't thought of it like that, yes, that's what I was doing....
'malcolmfrary' The wires melted right up to the ESC so cant use em again, mostly only bare wires left ! Iv ordered 2 inline fuses which I intend to fit between ESCs & battery, correct ? Props etc seem fine, still turn ok, but they'll have to come out anyway to fit new motors.
'jaymac' Yes, I'll need to pay special attention to that when refitting.

Thanks guys, mostly got in my  head whats needed now, but would appreciate you all telling me what makes of ESC (with BEC) you all recommend, or have had probs with, please.
John

[jaymac]

So Far Mtronics in  5 boats seem ok  the chinese 50 amp  had 2  go bananas  as did a  Graupner which put my PT boat full astern one third submerged.You might also consider for trials the mini circuit breakers at Maplins less then Ģ2 each 10A and auto reset bout the size of you thumbnail and about 1/4''thick
http://www.maplin.co.uk/p/100a-auto-reset-circuit-breaker-ak13p

[Coxn John]

Thanx jaymac, iv just studied their Viper Marine range, looks good, but having ordered a 'current draw meter' now i'll wait until iv done a test with that before I decide which one.  Im gonna avoid all the cheapies, theyre too much hassle, + if you could see how little room iv got to work in inside the boat you wouldn't want to do it twice...this will be my 3rd 'empty the hull' session 

[Time Bandit]

Even if some others told you, Iīm going to repeat it.
It seems that there is nothing wrong with your ESC if the wires and motors died of overcurrent.
Itīs impossible for the ESC to fry anything, itīs the motor that draws the amps.

Generally 50mm sounds too big for a standard 550 motor. If these are brass props with high pitch your motors will die again, this is way too much load on them.
Youīll need low rev motors for such a huge prop.

In what kind of boat are you using them? Pure displacing hull, half gliding/gliding?
If itīs a fast gliding boat, just decrease the size of the props.
If itīs a slow displacing hull, youīll probabaly need low rev motors.

[Coxn John]

Brass props, on the Lifeboat shown in my profile pic, but the motors were fine with those props before I upgraded to ESC & 2.4gig

[Time Bandit]

The props are definetly much too large.
35mm would fit and produce maybe 1/4 load at same speed of the boat.

I cant explain why it worked with other ESC (or did you use those 80's variable resistor controllers??) but your motors are definetly overloaded.
These large props work like a brake on your motors (since the hull canīt go as fast as it should be  @ 10.000 rpm > 20 km/h with those props, hull will maybe run half of it) and increase the amps.

Different ESC will not help anything, the motors will go up in smoke again!!!

If you want to use the 50mm props you need bigger motors with slower rev.
E.g. Robbe Power 755/40 (but @ 12V).

[Coxn John]

It was on 'Bobs Boards' if you remember them