Brushless motors

[harry smith 1Participant @harrysmith1]

Hobbyking in runners 3639-750,3648-850,3639-1100 or 3648-1450.
ESC car 60 amp(HK-60SL)or 100amp(HK-100A).
Program card (HK Prog-Card) dam easy to use.
Speed and Amp test on Spearfish at the weekend.
This ended some people's ideas on props.
Motor 3648-1450kv and ESC 60A only the cutoff voltage changed in the setup.

ON 3S 5800mah Lipo
Prop 2blade 38mm x 1.4 pitch 35Amps speed 27kph.
40mm x 1.4 pitch 37Amps speed 26kph.
Prop 3blade 37mm x 1.4 pitch 42Amps speed 26kph.

ON 4S 5800mah Lipo
Prop 2blade 38mm x 1.4 pitch 60Amps speed 36kph.
40mm x 1.4 pitch 55Amps speed 37kph.
Prop 3blade 37mm x 1.4 pitch 60Amps speed 37kph.

Pretty quick for an old girl!!!!

[BRYAN ASTONParticipant @bryanaston57723]

Greetings all

Tried the Hunstman with 12v battery ,performance was improved ,but not outstanding , battery lasted very well which shows that brushless are very easy on power consumption.

On my return to mission control I removed the outrunner motor and installed a 3100 kv inrunner which ran very well with the existing esc, time will tell if the performance is improved in the water. Waiting for delivery of 9.6v nihm, there seems to be a shortage of 12v nihms with a decent mah .

Watch this space

Regards Bryan

[Dave MilbournParticipant @davemilbourn48782]

**LINK**

Scroll down to last two on the page. 12v (nominal) charges up to over 16v which will try to turn a 3100kv motor at about 50,000rpm. To paraphrase Chief Brody in 'Jaws', "I think you're gonna need a smaller prop…" I also have concerns for the bearings in the prop shaft tube. Still, once you've boiled the lake you can have a nice cup of coffee!

DM

[BRYAN ASTONParticipant @bryanaston57723]

Dave

I do not intend to run the 3100 kv motor on 12v, I will be using the same two 7.2 3700 mah c pack in parallel as that used in the Sea Commander , and take it from there. I may use a 9.6 v pack as a experiment.

Regards Bryan

[Dave MilbournParticipant @davemilbourn48782]

Phew……………….but only relatively!
DM

[BRYAN ASTONParticipant @bryanaston57723]

Greetings all

Went to the pond/lake this morning with the large Huntsman with the newly installed 3100 kv brushless motor and two 3700 mah batteries installed in parallel , result ,disappointing to say the least ,it was no faster than using the outrunner motor, and then suddenly it started to cut out seconds later it would restart, I changed the batteries ,it made no difference

When I investigated the cause the motor was very hot to the touch ,,so was the esc even though the esc was water cooled.

I shall retire to mission control to lick my wounds and seek inspiration , who said this pastime was relaxing?

Regards Bryan

[Dave MilbournParticipant @davemilbourn48782]

Everything is being horribly overloaded, Bryan – like fitting a F1 engine into a quarry dumper truck. The boat is quite a bit bigger than your Sea Commander so you must expect it to need more power, but power doesn't equate to just raw rotational speed. If you spend some time researching the various forums you'll find that very few people use inrunners for anything except out-and-out speed machines with surface-piercing props and speed controllers priced in hundreds.

If there is an emerging "wisdom" it seems to be that outrunners with a fairly low kv rating (certainly <1000kv) and a good supply of volts is the way to go for larger models. They have the basic design requirements to produce a bucketful of torque without overstretching anything. It's a shame that the ESC you have will only handle 3S; I think the performance with your outrunner would be a revelation when running on 5 or even 6S batteries (assuming the motor is thus rated). At least you'd be heading in the same direction as the majority.

[BRYAN ASTONParticipant @bryanaston57723]

Greetings Dave

I will change the esc for one that can take a higher voltage and refit the outrunner in the Huntsman, it only takes minutes.

The inrunner and and esc I will fit into my MTB which is only 36 inches in length and light as a feather, that should shift , After modifications in the dry dock I will post an update

Onwards and upwards

Bryan

[Dave MilbournParticipant @davemilbourn48782]

Take care, Bryan! You're slowly painting me into a corner here!

DM

[BRYAN ASTONParticipant @bryanaston57723]

Dave

I have found a brushless esc that takes 6s lipos, what voltage is 6s lipos.

I will sort this out

Bryan

[Dave MilbournParticipant @davemilbourn48782]

Each LiPo cell is 3.7v, so a 6S pack is 22.2v.

[Malcolm FraryParticipant @malcolmfrary95515]

3.7 volts times 6 = 22.2 volts. More if charged, less if not.

[BRYAN ASTONParticipant @bryanaston57723]

Thank you Dave and Malcolm

Message received and understood ,

Bryan

[BRYAN ASTONParticipant @bryanaston57723]

Greetings all

Question about brushed motors, what causes a rudder servo to operate when the motor control is operated, the motor spins as usual, The steering control is not moved, I haven't got the wires crossed in the receiver.

The same transmitter and receiver operates normally in another boat.

Regards

Bryan

[Dave MilbournParticipant @davemilbourn48782]

RF interference at a guess. Possible solutions are:

Fit suppressor capacitors to the motor.
Route the receiver aerial wire well away from any other cables, especially those between the battery, ESC and motor. If it isn't a 2G4 set make sure the aerial is fully unwound and that as much of it is as vertical as you can get it. Don't wind it around underneath the deck.
Earth the metal can of the motor to the battery negative terminal.
Twist together the thick cables from the motor to the ESC (tightly isn't necessary).
Keep all thick cables as short as possible.

Here's the full monty from an expert **LINK**

DM

[BRYAN ASTONParticipant @bryanaston57723]

Thank you Dave I will study your link at length , it sounds very complicated, I will solve the problem , I have never experienced this before.

Bryan

[Malcolm FraryParticipant @malcolmfrary95515]

Is this in the brushless setup being discussed in this thread? If yes, then RFI should not be being generated since this originates in inductive circuits being disrupted, as when a brushed motor rotates and alternately disconnects and shorts its coils which are moving in a strong magnetic field.

I would suspect (especially if its a 2G4 radio) that the power supply is not quite up to the job. The servo works on comparing voltages, one derived from its power source, the other from the input signal. If either changes, it tries to take up a new position. 2G4 radios operate well out of any band that "normal" stuff can reach, so have the reputation of being interference free, and they will keep this reputation until more use is made of the band.

AM radios can be subject to interference, very typically responding to any signal that occurs in what should be the silent phase of the information frame. Any noise picked up in that time is regarded as the first signal of a new frame. Guess what is invariably connected to channel 1? The rudder servo. An unsupressed brushed motor will give lots of local interference for an AM set to pick up.

[Dodgy Geezer 1Participant @dodgygeezer1]

Posted by BRYAN ASTON on 03/06/2016 15:53:41:

Greetings all

Question about brushed motors, what causes a rudder servo to operate when the motor control is operated, the motor spins as usual, The steering control is not moved, I haven't got the wires crossed in the receiver.

The same transmitter and receiver operates normally in another boat.

Regards

Bryan

If the rudder servo jitters, or locks to one side when the throttle is operated, then it's probably interference. If it's a 27Mhz/40Mhz system, then remember that metal-to-metal contact can produce quite a lot of interference, and bonding such joints is a good idea…

If the rudder servo moves smoothly as the throttle is increased, and IF it's a modern, computer 2.4Ghz system, then it's POSSIBLE that you have the two channels connected in some way in the transmitter set-up. These systems have different settings for each model, so you would only see this for the one model setting.

I know this latter is highly unlikely, but it's an (obscure) possibility…

[BRYAN ASTONParticipant @bryanaston57723]

Thank you all for your suggestions and tips, I have never had any such problems like this before. It is a brushed 2.4 GH Z system , I changed the rudder servo just in case and the rudder thrashing calmed down slightly, I installed the transmitter and receiver in one of my other boats, no problems.

I will follow all your suggestions and see what happens, I am still solving the brushless problem in the Huntsman, awaiting the delivery of a higher voltage esc, and also see what happens there. Life is a continuos learning curve, I think

Watch this space.

Onward and upward

Bryan

[Dave MilbournParticipant @davemilbourn48782]

If the same Tx and Rx perform without problems in another model then it's unlikely to be either of those. That the problem persists even with a change of servo indicates that it's unlikely to be the original servo (but have you tested that out of the boat?). That leaves very little else except RF interference as the cause – unless there's a poor/intermittent connection somewhere in the wiring harness of the boat. Is the rudder servo thrashing even when the motor is not running? Are the servos "digital" types?

RFI is not completely unknown in a 2G4 set-up, but it's unusual because of the huge difference in frequency between the radio signal and any sparks from the motor commutator. If you have an exceedingly "dirty" motor then high-voltage back-EMF spikes could be breaking through the ESC and getting back to the receiver.

All you can do is keep reducing the possible causes by changing each part of the installation in turn until you get to the answer.

Dave M

[BRYAN ASTONParticipant @bryanaston57723]

Dave

The servos are not digital types, I haven't tested the servo out of the boat yet, the rudder only moves when the motor is running. The boat has never given me any problem before ,I fitted a brushless motor ( the inrunner I took out of the Huntsman) and that is when the rudder went mad , the motor ran perfectly and then it stopped and I could not get a response from the esc, about this time I considered starting smoking again. The brushed motor and brushed esc was refitted and ran perfectly but the rudder continued to go bananas and that was when I fitted a new servo, only slight improvement.

After I have sailed the Sea Commander and SS Bilbao tomorrow I will take up the battle again, I will win this fight in the end, keep coming with the suggestions

Bryan

[shipwrightParticipant @shipwright]

I have joined this lengthy thread rather late in the day …… I am guessing that your receiver/servo is powered from a BEC in the ESC. Have you tried powering the rx from a separate battery ? (my thinking here is that the BEC might be faulty). I don't know whether you will need to disconnect the positive wire in the connection between the ESC and the receiver (you do when using Mtroniks ESC and I have only ever used that brand of ESC). Just a thought.

[BRYAN ASTONParticipant @bryanaston57723]

Greetings Shipwright

I intend to change the esc to a spare one, I will post the results soon.

I will win this fight

Bryan

[Dave MilbournParticipant @davemilbourn48782]

What voltage battery pack are you using, Bryan? I may be able to find a suitable bi-directional diode (transient voltage suppressor) to clamp any back-voltage spikes. The only ones I have in stock are 25v. Don't panic – they're less than a quid!
BTW don't forget to try a different battery. If the same Rx and ESC work OK in another model then the possibilities are narrowing, especially when two different servos both show the same symptoms. Like Malcolm said, it could be down to an inadequate Rx power supply i.e. a faulty BEC or a bad cell in the battery pack.

Dave M

[BRYAN ASTONParticipant @bryanaston57723]

Dave

I wish to state publicly and to all readers of this forum that you are worth your weight in gold and that this magazine should have you on a retainer I shall elucidate. Changed the esc and twisted the power wires, result was rudder and motor perfect, took off the new esc and reinstalled the original one,still ran perfect, the cure was twisting the long power wires together,simples. You live and learn.

I shall now reinstall the original rudder servo one day , just as a matter of interest.

Many thanks

Bryan

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