Model Boat Mayhem

Please login or register.

Login with username, password and session length.
Pages: 1 [2] 3   Go Down

Author Topic: Overheating motor/ESC  (Read 2240 times)

mudway

  • Full Mayhemer
  • *****
  • Offline Offline
  • Posts: 451
  • Model Boat Mayhem is Great
  • Location: Sydney
Re: Overheating motor/ESC
« Reply #25 on: May 30, 2019, 10:36:26 AM »

Do you know the amps that you are pulling?


Damn, a typo > Well a Graupner 600 eco on the same prop and 9.6 V NIMH came out at 5,700 rpm and 6.4 amps.
Logged

Tug Fanatic

  • Full Mayhemer
  • *****
  • Offline Offline
  • Posts: 1,719
  • Location: England
Re: Overheating motor/ESC
« Reply #26 on: May 30, 2019, 11:11:53 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 motor revs to remain high while prop speeds stay relatively low. A win win situation.

Colin
Lovely model.
An MFA 385 is 975kv which with a 2:1 reduction (effectively a 487kv motor) is about the same as one of the low rpm 5 pole 500 (555) series motors. Whether it is better, has more power output/ torque or uses less power input???????
Logged

SailorGreg

  • Full Mayhemer
  • *****
  • Offline Offline
  • Posts: 993
  • Money talks - it says goodbye
  • Location: Hayling Island, Hants
Re: Overheating motor/ESC
« Reply #27 on: May 30, 2019, 11:34:59 AM »

Thanks to everyone who has pitched in on this. I (and, I hope, some others) have learnt a lot, not least that buying motors is a real minefield!

There are lots of gems of information on this thread that I for one will try and save somewhere.  But I am still rather confused - Colin says above that he has 2 380 motors in his Fishery Cruiser geared down 2:1.  Fine, but there is a plethora of 380s available, not all the same. Certainly a glance at e-bay shows lots, many without any technical data beyond the can size. How would I know what to buy to replicate Colin's setup?  (Sorry Colin, not having a go at you, just using your post as an example.) And his motors are low drain - what does that imply for turns, revs, torque...?  (Rhetorical question, just me musing!)

The more I find out, the more I realise I don't know. Yes, a real minefield!

Greg

Tug Fanatic

  • Full Mayhemer
  • *****
  • Offline Offline
  • Posts: 1,719
  • Location: England
Re: Overheating motor/ESC
« Reply #28 on: May 30, 2019, 11:53:57 AM »

Thanks to everyone who has pitched in on this. I (and, I hope, some others) have learnt a lot, not least that buying motors is a real minefield!

There are lots of gems of information on this thread that I for one will try and save somewhere.  But I am still rather confused - Colin says above that he has 2 380 motors in his Fishery Cruiser geared down 2:1.  Fine, but there is a plethora of 380s available, not all the same. Certainly a glance at e-bay shows lots, many without any technical data beyond the can size. How would I know what to buy to replicate Colin's setup?  (Sorry Colin, not having a go at you, just using your post as an example.) And his motors are low drain - what does that imply for turns, revs, torque...?  (Rhetorical question, just me musing!)

The more I find out, the more I realise I don't know. Yes, a real minefield!

Greg
The MFA385 is the standard low drain 400 sized motor. As you say there are lots of much hotter motors that look the same (the Graupner 400's being the standard example).

Without meaning to critisize anyone there is a lot of partial information when it comes to model boat drive systems. You have highlighted motors but equal problems exist with propellers. Plastic props are generally designed differently to metal props & there are at least 3 very different plastic prop design - s type, x type and 3/4 blade scale. There are even more variations with metal props with 3, 4, & 5 blade props of numerous different designs. These can have vastly different performances.

So if someone tells you they (as an example) have a 540 motor driving a 40mm prop & it pulls 8 amps you have a lot to find out before that becomes useful information.

There is also the problem that things are often not linear. Going from a 40mm prop to a 45mm prop of the same design might well double the power required to drive it from the same motor etc. Going from 2S to 3S will not increase power in & out by 50% but by a much larger factor whilst going from 3S to 2S will often save a very overloaded motor at the expense of power. 

I would equally be wary of the often repeated old adages like "keep the prop diameter smaller than the motor diameter" for exactly the same reasons.

My rule of thumb is to be very motor kv aware and where possible fit a larger motor that will not be working as hard. Gearing does the same thing.
 
Logged

DaveM

  • Full Mayhemer
  • *****
  • Online Online
  • Posts: 643
  • Why on earth do I do this?
  • Location: Nottingham
Re: Overheating motor/ESC
« Reply #29 on: May 30, 2019, 12:04:30 PM »

Greg
What Colin omitted to say is that a 380 and 385 are as alike as chalk and cheese, despite their physical similarities.

A 380 is a 3-pole motor which is very fast-revving (about 26000), usually runs on a maximum of 7.2v and should never exceed 10A. They are the ones which are often sold as Speed 400 motors. I've only ever used them in a Glynn Guest-designed airscrew-driven swamp boat and a 20" all-balsa semi-scale Swordsman. With a 25mm 2-blade bronze prop that thing went like greased weasel pooh!

A 385 is a 5-pole motor which can be run up to 15v, strangely has slightly less torque and is much slower. However at its maximum efficiency it draws only 1A c/w over 5A for the 380.

MFA's website has excellent data sheets on all of their motors, which include their "stock" 540/1 as well as what they term "noise attenuated" versions of the 540 and 385. Here's the link https://mfacomodrills.com/motors/motors.html  Just click on the motor you're interested in and it will download a datasheet in PDF format.
Dave M
Logged

Colin Bishop

  • Full Mayhemer
  • *****
  • Online Online
  • Posts: 10,644
  • Location: SW Surrey, UK
Re: Overheating motor/ESC
« Reply #30 on: May 30, 2019, 01:13:27 PM »

Quite right Dave & Greg, I should have made myself clearer, the motors are 380 size and fitted a long time ago so I can't recall where they came from which is why I described them as 380 type. They are definitely low drain and presumably 5 pole. They work very well in my setup. Props are 35mm standard scale 3 blade brass Raboesch.

Colin
Logged

SailorGreg

  • Full Mayhemer
  • *****
  • Offline Offline
  • Posts: 993
  • Money talks - it says goodbye
  • Location: Hayling Island, Hants
Re: Overheating motor/ESC
« Reply #31 on: June 07, 2019, 05:41:41 PM »

If anyone wants to know the outcome of my new motor fit, read on -

I purchased one of these and left everything else the same - 40mm kort prop, Mtroniks 20A Viper ESC, 6V SLA.  I ran the boat today (in between the rain) and kept it at full power for about 20-25 minutes.  Previously this would have resulted in a very hot motor and intermittent losses of power.  Not this time.  The motor was certainly warm/hot to the touch, but not as hot as previous motors, and there was no interruption of service.  I do believe the problem has been solved!  :} :}

Thanks again to all who offered advice and information.  I am slightly better informed on motor technology and much more aware what to look for when buying anything new.

Happy sailing

Greg

Tug Fanatic

  • Full Mayhemer
  • *****
  • Offline Offline
  • Posts: 1,719
  • Location: England
Re: Overheating motor/ESC
« Reply #32 on: June 08, 2019, 08:36:27 AM »

Greg
That is great. Do you know how any amps your are using?
Logged

SailorGreg

  • Full Mayhemer
  • *****
  • Offline Offline
  • Posts: 993
  • Money talks - it says goodbye
  • Location: Hayling Island, Hants
Re: Overheating motor/ESC
« Reply #33 on: June 08, 2019, 10:41:36 AM »

No.  I am not sure how to measure that under load.  The 20A ESC didn't get even a little warm so I guess it is operating well within its capability.

DaveM

  • Full Mayhemer
  • *****
  • Online Online
  • Posts: 643
  • Why on earth do I do this?
  • Location: Nottingham
Re: Overheating motor/ESC
« Reply #34 on: June 08, 2019, 11:20:38 AM »

No.  I am not sure how to measure that under load.  The 20A ESC didn't get even a little warm so I guess it is operating well within its capability.
I have one of these for that purpose. It's small enough to be carried on-board. No doubt there are others available e.g. from our inscrutable little friends...  http://www.4-max.co.uk/wattmeter-budget.htm

DaveM
Logged

roycv

  • Full Mayhemer
  • *****
  • Offline Offline
  • Posts: 2,564
  • Location: S.W. Herts
Re: Overheating motor/ESC
« Reply #35 on: June 08, 2019, 12:30:22 PM »

Hi all, many years ago i built a 16 inch loa Swordsman.  Power was a MFA 380 with 1 :2 gear reduction onto a 30 mm S series black prop running on 5 nicads (ex camera). 

The power consumption was about 40 watts so current over 6 amps.  The speed was dramatic and at full speed just 2 or 3 inches of hull in the water.
regards

Roy
Logged

chas

  • Full Mayhemer
  • *****
  • Offline Offline
  • Posts: 417
  • now in los montesinos Spain.
Re: Overheating motor/ESC
« Reply #36 on: June 08, 2019, 12:37:15 PM »

IF your SLA is the popular 4 or 4.5 ah 6 volt battery, you can estimate the current to be around the 5 to 6 amp area.
 A lighter 7.2 volt NiMH battery would make a dramatic difference.

Logged

Tug Fanatic

  • Full Mayhemer
  • *****
  • Offline Offline
  • Posts: 1,719
  • Location: England
Re: Overheating motor/ESC
« Reply #37 on: June 08, 2019, 02:34:41 PM »

I really like to know the current (amps) consumption of my motor/prop combination before I put the controller into the circuit - it is much cheaper that way! Battery to ammeter/ wattmeter to motor (which is attached to shaft & prop & in the water).

If you have the controller in circuit you can always start at low throttle which is also low amps & gradually ramp it up to full throttle keeping an eye on the readings. This is only a really bad idea if you dramatically overloaded the motor.

 
Logged

ivorthediver

  • Ivor the Diver
  • Full Mayhemer
  • *****
  • Offline Offline
  • Posts: 45
  • What ever Floats YOUR boat
  • Location: Cambridge
Re: Overheating motor/ESC
« Reply #38 on: July 07, 2020, 08:10:54 PM »

Ok I have been making model boats of differing size / type /style for a fare few years and prior to that model aircraft .


Since taking up model boating  on retirement I have always bought Action kit as I found that when I had issues and learning the ropes D M was a sound source of unbiased advice .
I have bought in total some 53 assorted items from there range and most have served me very well over the past 12 years of boating .


Whilst not always popular , I tend to speak from the shoulder and if asked try to help others .


I must admit that it is only recently that I have been a follower of this Forum and taken the time to read through the items that could have helped me prior to last weekends event .


Amongst others I have a Tug which is both great fun and helps drag less careful  members models at our club back to the shore line .
On this particular day I noticed that my Kort nozzles were very slightly offset , and thought ok I will put a little trim in when out on the lake , which I did , and all seemed well and after a good 1/2 hours run around the edges stopped in the centre and chatted to others ......as you do  %)


When I restarted the Tug and headed for shore she seemed hard to steer in a straight line and was very sluggish compared to her usual speed but managed to get her ashore [ incidentally this model has worked very well for over 14 months with only minor upgrades but has not been used during the last eighteen weeks of lock down .
When she reached shore and I berthed her in her cradle prior to wheeling her up to the assembly area I noticed the dreaded Bakelite aroma and new things were going to get worse , and when the superstructure was removed I noticed that the rear of one of the motors was partly melted . :o
When I carried out the autopsy I removed the starboard 540 geared motor and clip on cooling fan and binned them as they were not of any further use  <:( and ordered replacements and upon receipt and fixing found that only the Portside units functioned .
checked fusing which seemed fine , no lose fittings , so as I had a spare P94 which had been refurbished , fitted that and hey presto everything worked perfectly again


Now , I ponder the fact that was there an issue with this ESC that eluded me [ purchased in 2010 ] that having not been noticed slowly got worse and then threw the towel in ? {:-{
Should I have smelt a rat and not gone on the water  :(( .....still at least I was saved the embarrassment of being towed back in


Has anyone else had this experience ?
Logged

Ralph

  • Shipmate
  • *
  • Offline Offline
  • Posts: 22
  • Model Boat Mayhem is Great!
  • Location: Perthshire
Re: Overheating motor/ESC
« Reply #39 on: July 07, 2020, 09:41:15 PM »

This sounds more like something has got caught in the propellor - weed, poly bag etc which has then overloaded the motor making it overheat and in turn overloaded your speed controller letting out the magic smoke.  The extra drag of something in the prop would affect steering as well and I suppose it's possible it could fall off without you noticing as you lifted the model out.
Logged

ivorthediver

  • Ivor the Diver
  • Full Mayhemer
  • *****
  • Offline Offline
  • Posts: 45
  • What ever Floats YOUR boat
  • Location: Cambridge
Re: Overheating motor/ESC
« Reply #40 on: July 08, 2020, 09:22:16 AM »

Well Ralph , anything is possible I suppose , after all it is a Private Carp fishing lake and the banks are trimmed  occasionally so yes that is a possibility but not one that the club have had before that I know of and the club has used it since 1950 when it started


The Lake is feed [ amongst other sources ] by surface water from the A14 draining off and was a gravel quarry , very murky , and at least 5-7 metres deep in places to my certain knowledge , none the less something to be avoided if possible eh .......
Logged

DaveM

  • Full Mayhemer
  • *****
  • Online Online
  • Posts: 643
  • Why on earth do I do this?
  • Location: Nottingham
Re: Overheating motor/ESC
« Reply #41 on: July 08, 2020, 10:24:43 AM »

Now , I ponder the fact that was there an issue with this ESC that eluded me [ purchased in 2010 ] that having not been noticed slowly got worse and then threw the towel in ?

Electronic speed controllers don't wear out or become sluggish, Ivor - certainly not in my experience. If it has been working well for 14 months then there's no reason why it should suddenly stop working without some external interference. Motor cases melt because they overheat, and that's usually caused by an excessive load. That in turn will lead to excess current drain and probable damage to the ESC.

I agree with Ralph's suggestion that something fouled the prop. Kort nozzles are more prone to this because weed or a polybag can easily become jammed between the prop and the nozzle. This would also explain the steering problem. Incidentally if you suspect that something has fouled the prop then a quick burst of full reverse often clears it.

Dave M
Logged

ivorthediver

  • Ivor the Diver
  • Full Mayhemer
  • *****
  • Offline Offline
  • Posts: 45
  • What ever Floats YOUR boat
  • Location: Cambridge
Re: Overheating motor/ESC
« Reply #42 on: July 08, 2020, 10:55:05 AM »

Thanks for the response Dave ...appreciate it .


If I implied that the product was faulty let me correct that here and now , and the comment that I bought it ten years ago should allay that fear as it has worked very well in a 6ft aircraft carrier driving two 800 motors without batting an eyelid and other models requiring an ESC that have passed through my workshop , so it is a prov-en animal to me and feature rich ....an excellent selling point ..... and it will be winging its way back to Component -shop for refurb ....just like the one which was installed to get me mobile again .


My comment was more self critical of ME thinking that the misalignment  could be offset on the transmitter when I saw that the previously straight alignment of the twin Kort's had changed  :o and as I hope I stated to others I seem to have spent a lot of money over the years on products that I have found to be worthy of use [ and that total doesn't include all the ancillary cables / connectors / meters , motors / clips , catches / led's / heat shrink and servos that have been used in fit outs from Iain !]


It seems likely that it could have been some type of flotsam that was ingested in the starboard Kort , but again as I said this is a first and came as a shock , but as I said as recovery tug , it could have been worse to have been recovered myself  O0
Logged

malcolmfrary

  • Full Mayhemer
  • *****
  • Offline Offline
  • Posts: 5,683
  • Location: Blackpool, Lancs, UK
Re: Overheating motor/ESC
« Reply #43 on: July 08, 2020, 05:50:30 PM »

A truly annoying thing about some types of weed is that they do their evil, then fall off just as the boat leaves the water.
Usually a motor with a melted end cap has as its heat source a bearing giving up or the brush gear getting tired and generating more heat than it should.  I've seen a heavily overloaded motor (a 280 running on a 3S LiPo driving a 35mm 3 blade prop) burn its label off and save the boat further harm by melting the solder on its tags without harming the moulding.  Probably a re-invention of the fuse, that.
Logged
"With the right tool, you can break anything" - Garfield

ivorthediver

  • Ivor the Diver
  • Full Mayhemer
  • *****
  • Offline Offline
  • Posts: 45
  • What ever Floats YOUR boat
  • Location: Cambridge
Re: Overheating motor/ESC
« Reply #44 on: July 08, 2020, 06:08:34 PM »

Thank you for that gem Malcolm , and glad to see that I am not alone in this situation , and hope that my choice of motor / prop ratio stands the test of time , which from February last year it has , with guidance from others who know better than me  O0
Logged

Colin Bishop

  • Full Mayhemer
  • *****
  • Online Online
  • Posts: 10,644
  • Location: SW Surrey, UK
Re: Overheating motor/ESC
« Reply #45 on: July 08, 2020, 06:11:29 PM »

I appreciate it is a matter of choice but I always fit a fuse between the motor and ESC to protect the motor in this sort of situation. On a twin screw model I have a master fuse in the positive lead from the main battery(s) and subordinate fuses between the motors and their ESCs.

It's the easiest thing in the world to foul a prop and the fuses cost pennies. It is easy enough to find the stall current of the motor with an ammeter on the bench if it isn't already published in the specs (don't jam the shaft for more than a second). I also measure the motor draw under load with the boat stationary in the water as that is the most you are likely to experience on the pond. The fuse should be a bit above this value to allow for start up spikes but below the motor stall current.

My Dad worked in the electricity supply industry - he was a great believer in fuses and so am I.

Colin
Logged

ivorthediver

  • Ivor the Diver
  • Full Mayhemer
  • *****
  • Offline Offline
  • Posts: 45
  • What ever Floats YOUR boat
  • Location: Cambridge
Re: Overheating motor/ESC
« Reply #46 on: July 08, 2020, 10:22:07 PM »

Hmmmm  Colin .......this is going to ruffle some feathers I fear , but every boat I build has a P92 fuse board as standard for the very reasons you elude  too  and in this case it should have been protected but there again perhaps the 15 amp fuse was to high as it was in line for two 540 2.5=1 motors and two clip on cooling fans as per the C /shop motor case size .....which up to now have been fine.....or perhaps an accident waiting to happen  ;D
Logged

Martin [Admin]

  • Administrator
  • Full Mayhemer
  • *****
  • Offline Offline
  • Posts: 19,852
  • Location: Peterborough, UK
    • Model Boat Mayhem
Re: Overheating motor/ESC
« Reply #47 on: July 09, 2020, 04:45:26 AM »

Logged
"This is my firm opinion, but what do I know?!"    -   Mayhem FaceBook Group!

ivorthediver

  • Ivor the Diver
  • Full Mayhemer
  • *****
  • Offline Offline
  • Posts: 45
  • What ever Floats YOUR boat
  • Location: Cambridge
Re: Overheating motor/ESC
« Reply #48 on: July 09, 2020, 07:35:55 AM »

Thank you Martin , and having just read through this worthy discussion I am of the opinion that if these self resetting fuses are what is claimed why are they not fitted as standard in the distribution boards that Action currently sell  :o


I am not looking for an argument with either Iain or Dave but to idiots like me these sound a great idea and if they cost an extra fiver each they would be a good idea and I for one would use them However If I decide to fit them and sink my model and then start pointing fingers at the supplier who reply by saying that They do not fit them as standard and as such I caused the issue which resulted in the loss ..........where do I stand then

IF as claimed by the posters on that thread they have been around a long time and they are the dogs whatnots why haven't "Component -shop" fitted them as standard .....as they could be argued as a cost effective selling point that not only protects the model but resets itself ...........it sounds like a minefield of litigation that they would prefer to avoid


Other than the incident mentioned by me I have lost two models ......one caused by me fitting a receiver  bought on eBay which WAS NOT a genuine Spektrum product which having had the TX serviced by the suppliers [ so that was not the cause ] and the correct RX was four times the price I paid for what I thought was a genuine RX I wrote off a model in excess of 1K [ which unbeknown to me was insured on my house contents policy and I was paid in full ,.....and the other was a vac formed hull cut in half be a speeding modeller which sank ! ,but it focuses your mind on Who was to blame !

If I risk anything ...thats my problem ........however........ if I fit purpose made equipment supplied for a specific purpose[ supplied with specific types of Fuses ] and then alter it ......thats also my problem and I suspect I would not have leg to stand on
or am I wrong again !


Anyone care to give a view on that side of things .....as that would be very useful
Logged

Colin Bishop

  • Full Mayhemer
  • *****
  • Online Online
  • Posts: 10,644
  • Location: SW Surrey, UK
Re: Overheating motor/ESC
« Reply #49 on: July 09, 2020, 09:31:47 AM »

Can't you just substitute resettable blade fuses for the ones supplied if that is what you want? They appear to cost 4-5 each for either manual or auto reset options from a quick look online.

I probably would stick with the standard types as I have only infrequently experienced fuses blowing. Why pay more for something you are not likely to need? If you do get weed around the prop then an auto reset isn't likely to get the boat moving again so there would seem to be little benefit in the more expensive option. You can buy a lot of standard fuses with a variety of options for the price of a single resettable which is only good for one value.

Horses for courses and if you buy the ACTion P112 you can choose the option you want.

Colin
Logged
Pages: 1 [2] 3   Go Up