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Author Topic: Overheating motor/ESC  (Read 10228 times)

SailorGreg

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Overheating motor/ESC
« on: May 28, 2019, 06:48:38 pm »

I ask the following question with some trepidation as it seems the sort of thing I should know, or be able to work out for myself, but I can't. So here we go -

Last year I built myself a Springer tug.  Standard size and hull shape. I fitted a Speed 600 motor and a 20A Mtroniks Viper, because I had them to hand.  The prop is a 40mm kort operating in a steerable nozzle (because I had never used a kort nozzle and fancied giving it a go).  6V SLA to provide the oomph. It soon became clear that after running for a while things got rather warm.  The motor was too hot to touch comfortably, and the ESC warm to the touch. However, everything worked fine so I didn't worry.  Later, though, I started getting brief losses of power (1-2 seconds), which I couldn't replicate out of the water on the bench.  I assumed there was some mismatch which was causing the ESC to trip out (too hot?).  Some brief research led me to a table on the Model Boats website which suggested the Speed 600 was really for planing boats (clue in the name I guess) and something like a 540 would be more appropriate.  I bought a 540 from e-bay, fitted it and gave it a run.  Same problem, perhaps even worse.

So - is my propeller too big and simply overloading the power train? Is the motor and ESC mismatched in some way?  What do others use in a bog standard Springer?

Help!

Greg

Colin Bishop

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Re: Overheating motor/ESC
« Reply #1 on: May 28, 2019, 07:05:41 pm »

 Your 540 could be one of several specifications. Many of them are very power hungry but unless you have a data sheet for it you won't know what you have. Maybe better to look at a 545 low drain motor but no doubt others will be able to advise you.

Colin

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Pirate

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Re: Overheating motor/ESC
« Reply #2 on: May 28, 2019, 07:43:16 pm »

Hi Greg,
 I must agree with Colin. Motors are a mine field now, a good bit of research is needed before purchasing any nowadays. A number on the 'can' or advert means very little, and the self same motor if purchased as a pair can vary up to 15% in revs and draw to each other. In general a standard 600 johnson's motor will give all that is needed for a springer and a tad more. A 555 motor is cooler running and not so greedy. A 540 motor varies from a HOT race spec down to a hyper efficient dawdler. No doubt a hundred more opinions will arrive to advise you.
 Step wisely and read the small print!!


Good luck


Pirate
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chas

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Re: Overheating motor/ESC
« Reply #3 on: May 28, 2019, 11:22:47 pm »

Using a 540 or 545  in a springer is a pretty standard choice, but because of the huge variety it's best to buy one from a specialist supplier who stocks motors for the job. The MFA 540 is commonly used, as are motors from decent model shops like Cornwall model boats and many others.
   A p30 or p35 propeller will be about right, much larger and you risk overloading and overheating, as you found out.
I use an MFA 540 on 6 volts p 35 prop, it barely gets warm and I've never run the battery down.

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grendel

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Re: Overheating motor/ESC
« Reply #4 on: May 29, 2019, 07:40:21 am »

on my model I started out with a 385 motor, this was running very hot, so I upgraded to a 540 size, this draws approximately 1.5A and runs cool to the touch, this with a 35mm prop, I believe I used the low noise 5 pole motor.
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malcolmfrary

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Re: Overheating motor/ESC
« Reply #5 on: May 29, 2019, 10:08:45 am »

Quote
I fitted a Speed 600 motor and a 20A Mtroniks Viper, because I had them to hand.  The prop is a 40mm kort operating in a steerable nozzle (because I had never used a kort nozzle and fancied giving it a go).
SPEED 600 + 40mm prop.  Thats the clue.  Motor intended to drive a small prop fast, driving a larger prop than intended and having its natural speed dragged down severely.  Classic recipe for an overheated motor and short battery life.
From the original Springer thread on RCGroups (where it started) -
Motors, any 500 series motors will work.
Try using 27 turns or higher.
Many modlers will recommend a 45-55 turn motor to maximize runningtime and minimize heat.
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DaveM

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Re: Overheating motor/ESC
« Reply #6 on: May 29, 2019, 11:16:06 am »

There are many 540-sized brushed motors available for rock-crawlers, with anything upward of 27 turns. These can be had for less than £10 if you look on E-Bay. That way you'll have a pretty good idea of what you're getting inside that otherwise anonymous metal can and thus what sort of performance you'll get out of it.

DaveM
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SailorGreg

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Re: Overheating motor/ESC
« Reply #7 on: May 29, 2019, 02:54:20 pm »

Thanks all. I have a 55 turn motor on the way and will probably get a 35mm prop as well.  I will report on success, assuming it is successful.


Greg

DaveM

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Re: Overheating motor/ESC
« Reply #8 on: May 29, 2019, 03:16:55 pm »

Greg
Pardon me if you already know this but if you're still going to use the Kort then stay with the 40mm prop, too. That motor should easily be capable of spinning it without undue current drain.

DaveM
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SailorGreg

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Re: Overheating motor/ESC
« Reply #9 on: May 29, 2019, 03:33:25 pm »

Thanks Dave.  I thought I would try the 40mm with the new motor, and then a smaller prop if I still had problems.  I am grateful for your confidence-building advice.  :-))
Greg

DaveM

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Re: Overheating motor/ESC
« Reply #10 on: May 29, 2019, 03:38:22 pm »

Sounds like a good plan! And you're welcome.
DM
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Netleyned

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Re: Overheating motor/ESC
« Reply #11 on: May 29, 2019, 03:55:13 pm »

My Springer, a Models By Design Hull and Kort Nozzle with a 40mm Kort Prop driven by a 540/1
powered by 6V SLA and Mtroniks 20A esc has been
running up and down the lake as a rescue vessel
for the last 8 years. I fitted a water cooling coil
but I don't think its doing a lot as rescues involve
backing and tooting so not much through the pickup. 2 hours or more each session has never used the
batteries 2x4.5 A 6V SLA to low volts.
Today, one push back and one yacht in irons turned through the wind.
Ned
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Tug Fanatic

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Re: Overheating motor/ESC
« Reply #12 on: May 29, 2019, 04:30:24 pm »

Quite a lot of precision about motors here but very little re the load (propellers).
Are you all using the same prop, eg 3 blade 40mm Kort PropShop prop, or are some using 4 blade & others plastic?
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SailorGreg

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Re: Overheating motor/ESC
« Reply #13 on: May 29, 2019, 06:36:18 pm »

Well mine is a 4 blade Raboesch prop running in a Models by Design Kort nozzle.

unbuiltnautilus

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Re: Overheating motor/ESC
« Reply #14 on: May 29, 2019, 07:13:03 pm »

That 55 turn crawler motor will have oodles of low end torque, just right for a 4 blade brass prop. The 4 blade brass prop also explains your problems previously with 540/600 motors.
There is much advice above, most of it vague unfortunately. Just using a '540' wont guarantee a good performance, just using a 5 pole version also no guarantee. What you need is good, hard advice, based on experience. Netleyneds advice regarding the MFA RE540/1 is spot on. This motor is a fairly lightly wound, medium power motor, ideal for scale use, up to a 40mm prop. MFA also produce something called a RE540LN, which, just to add to the confusion, has a can length more like a '550' type motor, it is also a 5 pole motor, which is lighter wound than their standard 540/1. This is slower and has greater torque, so is once again good for slightly bigger props, I would say up to 45mm at a push.
The new crawler motors coming onto the market now are brilliant direct drive scale motors, the more windings the more torque. I have a 70 turn motor, and the torque is incredible. I think it could turn over a 50mm prop with ease.
As a simple rule of thumb, the more windings a motor has, the more grunt it has and the less it will be loaded down with the wrong prop. Too much load, too high current. The problem is many motors dont offer this advice. I often resort to looking into the cooling hole of the motor. If it has many thin windings it will be slower but more suitable at lower speeds. If it has less windings that are thicker, it will be faster, more ampy and run hotter.
Different motors for different jobs..
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Tug Fanatic

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Re: Overheating motor/ESC
« Reply #15 on: May 29, 2019, 08:30:09 pm »

If we add some detail the Integy 55 turn 540 crawler motor is around 1100kv whilst the MFA 540/1 is around 1250kv and the RE540LN I believe has a kv of around 500kv.

A 70 turn crawler motor has a kv of around 875kv.


The quality of the motor (particularly the magnets) has a large effect on power & efficiency.
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mudway

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Re: Overheating motor/ESC
« Reply #16 on: May 30, 2019, 02:02:00 am »

An Integy 55T in the water with a 35mm 3 blade Raboesch warship prop and 3S lipos pulls 9.9 amps turning at 8,800 rpm.
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unbuiltnautilus

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Re: Overheating motor/ESC
« Reply #17 on: May 30, 2019, 07:04:19 am »

An Integy 55T in the water with a 35mm 3 blade Raboesch warship prop and 3S lipos pulls 9.9 amps turning at 8,800 rpm.


It would be interesting to know what sort of current the same set up pulls at 6v/7.2v/7.4v, which would be the voltage band most smaller scale models would be operating in.
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unbuiltnautilus

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Re: Overheating motor/ESC
« Reply #18 on: May 30, 2019, 07:08:58 am »

If we add some detail the Integy 55 turn 540 crawler motor is around 1100kv whilst the MFA 540/1 is around 1250kv and the RE540LN I believe has a kv of around 500kv.

A 70 turn crawler motor has a kv of around 875kv.


The quality of the motor (particularly the magnets) has a large effect on power & efficiency.


These all seem to cover scale needs well. What we now need to know is the equivalent performance of the motors I often see fitted in scale boats, that really have no place in them. The Johnson 600/Vision 600, Tamiya type 540 motors, some of those more bitey 5 pole 545s...just as a good point of reference.
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canabus

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Re: Overheating motor/ESC
« Reply #19 on: May 30, 2019, 09:00:59 am »

Hi Sailor

I am using 540 rock crawler motors(55 and 60 turn) in my Hellen fishing boats with 3blade brass props (50mm and 60mm).
Running 7.2 volts with no heating problems at all!!!
The motors are from Banggood.
I have a 80 turn one but its a bit too low rpms on 7.2 volts, but, OK on 12 volts.

Canabus
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Tug Fanatic

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Re: Overheating motor/ESC
« Reply #20 on: May 30, 2019, 09:12:43 am »


It would be interesting to know what sort of current the same set up pulls at 6v/7.2v/7.4v, which would be the voltage band most smaller scale models would be operating in.

Re Integy 55T & Roboesch 3Bl 35mm on 11.1v (3S)
I would expect (not proven) that at 7.2v the answer would be around 3.5 - 4amps and around 6000rpm which would give around 50% the static thrust for 25% of the power consumed (watts). I would love to see measured data to confirm/ deny theses numbers.

At 6v the answer is slightly complicated as scale model boat owners often use small lead acid batteries which can have a significant voltage drop if asked to provide more than half their mah rating ( eg 3amps for a 6ah battery).
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mudway

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Re: Overheating motor/ESC
« Reply #21 on: May 30, 2019, 09:19:00 am »


It would be interesting to know what sort of current the same set up pulls at 6v/7.2v/7.4v, which would be the voltage band most smaller scale models would be operating in.


Well a Graupner 600 eco on the same prop and 9.6 V NIMH came out at 5,700 rpm and 6.4 volts.

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Tug Fanatic

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Re: Overheating motor/ESC
« Reply #22 on: May 30, 2019, 09:20:05 am »

Hi Sailor

I am using 540 rock crawler motors(55 and 60 turn) in my Hellen fishing boats with 3blade brass props (50mm and 60mm).
Running 7.2 volts with no heating problems at all!!!
The motors are from Banggood.
I have a 80 turn one but its a bit too low rpms on 7.2 volts, but, OK on 12 volts.

Canabus

Do you know the amps that you are pulling?
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Re: Overheating motor/ESC
« Reply #23 on: May 30, 2019, 10:06:32 am »

As an aside & hoping that this might help someone.
A brushed motor acts as a generator just as much as it does a power source so if you want to know the kv of a motor & you have a known rpm source - a drill often has a published rpm - and a voltmeter it is easy to appoximate a kv. Drive the motor with the drill and measure the voltage that the motor develops. So if you have a 1400rpm drill and the output voltage is 1.6v you have a 1400/1.6 =  875kv motor.
This will be approximate & you obviously would need a lot of rpm with a high kv motor to get an reasonable estimate but it works for scale type motors at least it gives you some idea of what type of motor (scale v racing) you have.
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Colin Bishop

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Re: Overheating motor/ESC
« Reply #24 on: May 30, 2019, 10:24:44 am »

I am constantly surprised at the mismatches of motors and props in scale or scaleish model boats which often result in either overheating, poor performance or both. Any significant heat in a scale model represents inefficiency somewhere in the propulsion setup.

My Fishery cruiser can be seen at way over scale speed in the video on the 2019 Mayhem page (55 seconds in). This boat is four feet long and weighs around 10lb (4.5kg). It is powered by two low drain 380 type motors geared down about 2:1 via belt drive to 11 inch M4 shafts with 35mm props on the end. Battery is a 7.2aH Nimh pack.

At full speed, using both motors the total current draw is just 2.5 amps in the bath, probably a bit less on the open pond. Nothing even gets slightly warm.I haven't measured current draw at cruising speed but it is probably under 1 amp per motor.

There are often huge efficiency advantages in gearing the shaft down as it helps moror revs to remain high while prop speeds stay relatively low. A win win situation.

Colin
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