Speed controllers

[Len Morris 2Participant @lenmorris2]

Hi Everybody,

How hot do modern speed controllers (ESC's) get and what is the best way to mount them? I'm only asking about scale model applications. They all seem to be encapsulated electronics within an aluminium heat sink casing but without any attachment lugs. Is it ok to stick them down with double sided sticky pads or do they need to be attached more firmly to a heat dissipating surface?

Len

[Len Morris 2Participant @lenmorris2]

[shipwrightParticipant @shipwright]

Hello Len,

Please specify the exact type of ESCs that you are using and the rating of your motor(s) – eg 12 volt 2 amp at full load = 24 watts. Most ESCs are very efficient nowadays and heat dissipation is not usually a problem. Only exception is when you are using very powerful motors and drawing lots of current. As an example I have 2 x 10 amp ESCs in one of my boats and 2 12 volt motors drawing between 1 and 2 Amps. The ESCs are barely warm. High performance ESCs are available that have water cooling but I doubt that many model boaters require that unless they in model power boat racing.

Ian

[Mark Jarvis 2Participant @markjarvis2]

HI Len

Like Shipwright i use 2 types cheep chinese esc off ebay, the blue anodised ones, and even with weed round the prop and shaft they didn't get hot.

The other type are Electronize which are about 20 years old and her been hammered over the years with my Huntsman, they have an easy life now in Yorkshireman and Amsterdam. But still don't get hot even on 24volts.

Hope this helps

Mark

[Dave MilbournParticipant @davemilbourn48782]

Len
I use self-adhesive Velcro strips to fix electronic units to the inside of my models. It's firm enough to secure them but much easier to remove them than if you use double-sided tape or foam pads.
Dave M

[Malcolm FraryParticipant @malcolmfrary95515]

Modern ESCs work by switching fully on and off rapidly. Heat is generated as a result of power dissipated in the ESC. When fully switched on, current flows, but no voltage is dropped across the output transistors, so no power, no heat. When fully off, there is no current, so no power, no heat. Most of the heat that is generated happens during the short, but finite, time involved with them changing state between on and off. Since there is yet to be a perfect semiconductor, there is a small loss giving some heating, but if the ESC was properly designed for boat use, the heatsinking provided by the case will be adequate.

For mounting, velcro is good, as is double sided tape pads, as is finding a corner where it can sit comfortably. As long as the fins can have air flow over them. The heat, such as it is, is not going through the mounting, it is headed the other way.

[Len Morris 2Participant @lenmorris2]

Hi Everybody,

A big thanks to all of you for your replies. Just so you know, the application is mi submarine Resurgam (the motor is a 6 volt 545 and the ESC is a Viper 15). I was concerned because there is obviously no cooling air flow inside the hull.

Hadn't even considered Velcro! Excellent solution! Off now to the local knitting and sowing shop.

Well done chaps!

Len

[Dave MilbournParticipant @davemilbourn48782]

That speed controller shouldn't even get warm with that motor/battery combination. Make sure you buy the self-adhesive Velcro; sewing it to a metal hull isn't my idea of fun.
DM

[Len Morris 2Participant @lenmorris2]

Hi Dave, Thanks for your reassurance. When it comes to electrical / electronic thingies you're the man!

Now full of confidence!

You are dead right about getting the self-adhesive Velcro. Had great difficulty trying to solder the normal stuff!

Len

[ashley needhamParticipant @ashleyneedham69188]

The motor and esc of my sub gets quite warm..the interior volume is very small and although , as above, the currents and so on are well within the esc spec , there is nowhere for the small amount of heat to go….

Ashley

[Dave MilbournParticipant @davemilbourn48782]

Ashley
Len's sub is all metal, a much better conductor of heat than glassfibre, wood or styrene. Immerse that in the 'oggin and you've a pretty good heat-sink for any hot air inside it. I wouldn't lose a wink of sleep over the thing getting too hot.
Dave M

[Geoff SleathParticipant @geoffsleath41411]

My calibrated finger is set to 50 degrees. If a component is any hotter than that I need to remove it sharpish. So, if you can hold your finger on the esc heat sink then you haven't much to worry about. I have a very big trainer style aeroplane (84" ws) which I electrified rather than use a noisy, oily .60 size engine (10cc). It draws up to 50 amps from a 4S (14.8v) LiPo and the 60 amp esc barely gets warm. Admittedley, a much friendlier environment than your submarine (the fuselage is spacious) but, provided your esc is used well below its rated current it should be OK. The bargain esc are less capable at their rated current than more expensive ones so my practice is to run them conservatively and arrange for full throttle only to draw a modest current by not overloading it with a big propeller. Remember an that an esc works harder at half throttle than full.

Tempting though it is to attach the esc on the flat side, don't do it. That's the heat sink and needs to be open to whatever air there is around it. If yours is big enough to have a finned heat sink then it's more obvious.

btw, some 2.4 gHz systems (eg Frsky Taranis) have telemetry feedback and temperature is one of the things you can monitor remotely. So if your RC system allows it then it's worth thinking about.

Geoff

[Len Morris 2Participant @lenmorris2]

Hi Geoff,

Thanks for that. I'm obviously very small beer compared with your stuff! I don't think mi MIG welder draws 50 amps! Problem with a sub is that by the time you've unscrewed everything to apply the calibrated finger its all cooled down. I like your comment about ESC's working harder at half throttle. It's what I suspected. At full bore they must be just a switch with not much else to do. At low speed they are doing a job hence the heat generation.

Anyway I'm quite relaxed now that my Guru (DM) has spoken.

Didn't know you could get TF on RC. Being able to monitor pressure would be brillliant.

Just so you know, subs can't use 2.4 or 2.7 gHz systems very well as the signals just bounce off the water. We're on low frequency at 40 mHz. I'll check out Frsky Taranis .

Len

[Geoff SleathParticipant @geoffsleath41411]

I know full-size submarine communication is at low frequencies ( around 200kHz) because of the water effects but I assumed model subs being only just below the surface would be much less susceptible. Don't you stick the antennae up so they pierce the surface?

If there's a 40Mhz JR RF plug-in module it would fit in the Taranis but you'd have to use JR receivers which probably wouldn't have telemetry capability. You need to use 2.4gHz for that and I guess the combination of a metal hull and the water makes it useless for you.

Submarines are a fascinating modelling challenge, I would think. And they sail in 3D like aeroplanes fly in air, with the added difficulty of not being able to see them very well.

Geoff

[Kev.WParticipant @kev-w]

Hope you don't mind me intruding, but I'm new to electric boating (always be a yacht man until now) & I just wondered if anyone on this thread has any 'hands on' with this ESC from 'Sunshine Electronics' from Leicester ..

"320 Amp brushed speed controller"

**LINK**

Would be most appreciative of any advice that may stop me wasting my cash.

I intend powering a Billings 'Nordkap' with a 'Sun 555' motor & brass '40' 3 bladed prop.

[Dave MilbournParticipant @davemilbourn48782]

Kip

320A @ 7.2v = 2.3Kw, or 3.2HP. If you believe that you can put that amount of power through something with cables that thin then you'll believe anything. That said, I doubt if your motor/prop combination would draw much more than about 5A so go ahead, but I'd bet that the low-speed control isn't much to write home about. That's essentially a car speed controller for hot-wound motors and high speeds.
You'd be better advised spending your money on a 'name' brand unit designed for model boats such as Electronize, MTroniks, ACTion or Microgyros. All British-made with proper warranties and service if you ever need it.

Suit yourself, as I usually say.

Dave M

[Len Morris 2Participant @lenmorris2]

This is turning out to be a well interesting post! I personally just want to sail about safely at approximately zero knots. Everybody else seems to want to bung stuff into space and past the moon! 320A, eye watering!

Len

[Len Morris 2Participant @lenmorris2]

Hi Geoff,

On a sub you can keep the aerial above the surface – but then it ain't a sub!

I think your job is much harder. Flew model planes at one time. Dot in the sky. No idea of orientation. Crash land. Find it. Rebuild. Doh!

Full marks to you, but give me a sub any day (I can wade in and get it)!

Len

[Dave MilbournParticipant @davemilbourn48782]

Posted by Len Morris 1 on 22/10/2014 03:06:32:

This is turning out to be a well interesting post! I personally just want to sail about safely at approximately zero knots. Everybody else seems to want to bung stuff into space and past the moon! 320A, eye watering!

Len

Len

There are MOSFETs (the components at the heart of all electronic speed controllers) available these days which have a resistance of micro-Ohms and can theoretically handle continuous currents like this. The problem is that you have to conduct that amount of power to and from them and this needs very substantial cabling – something which is not fitted to such a small unit. For practical purposes I usually divide such current ratings by a factor of ten. For this reason – and the fact that they are usually badly assembled from inferior components – what Geoff calls "bargain ESCs" are IMHO anything but a bargain, unless you like replacing them on a regular basis.
For the sort of models you make then a 20A speed controller is probably as big as you'll ever need, and 14AWG silicon-covered multi-strand cable will handle 40A comfortably (which is about the size fitted to these things).

Dave M

[Kev.WParticipant @kev-w]

Thanks Dave, thought it had to be a mistype in the amps quoted, which is why I asked, have looked at Microgyros but he's waiting for components to build them, others in the club use MTroniks, so will try one of those.

[Dave MilbournParticipant @davemilbourn48782]

Kip

The 15A one is more than big enough for your model.

Dave M

[Kev.WParticipant @kev-w]

Ok Dave, thanks for that, we learners have to start somewhere, grateful for those that have & can share.

[Mark Jarvis 2Participant @markjarvis2]

HI Kip

I have one of the 320 amp ESC's, works ok but i got mine direct from china for £7, identical to the one shown, restricted to 7.2volts, better to go for one of the 50 amp ones in the blue anodised case.

Mark

[Dave MilbournParticipant @davemilbourn48782]

Posted by Mark Jarvis 2 on 24/10/2014 22:40:00:

better to go for one of the 50 amp ones in the blue anodised case.

Mark

Oo no, missus! These also reflect my lecture about Chinese amps. I've had maybe six or seven of these handed to me ('ere, clever dick – can you do something with this?) which have blown MOSFETs despite being fused at 15A or less. They are only cheap for a reason – and no, there is nothing you can do with them once the power transistors have blown, apart from using them as ballast. At the risk of being boring, buy a British-made ESC and you'll have the security of a decent warranty and repair/replacement if something does go wrong. Buy everything cheap from China and pretty soon that will be your only choice. Remember what happened to British motor cycles?

Dave M

[Paul TParticipant @pault84577]

Being serious for a change.

DO NOT BUY THE CHINEESE SPEED CONTROLLERS AS THEY BLOW UP!

Been there, spent the money, regretted it ever since.

The old adage of buy cheap and buy twice is very apt for these blue shiny trinkets

Paul

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