New 30AMP ESC burntout?

[Peter Beeney]

   Erfolg,
          I’m afraid I would never be able to aspire to your level of accuracy. I would only ever be within my limitations. However, I’m not entirely sure about it all being a waste of time in the real world of hobbies. I’ve been testing modellers batteries for many years, particularly tx and rx packs. From the owners point of view this just to find out their general health in terms of capacity but I’ve always treated it as a safety check so I have a firm specification and I do keep to it as accurately as possible. If this has prevented only one unnecessary crash then I consider that it’s been worth it. A far as I can see, there are indeed few standards and specifications within aeromodelling circles, is this why we seem to get a number of failures? I like to think that if my actions, with the batteries, were ever queried for any reason, I would be able to justify them.
   From where I’m standing, the ESC and motor are inseparable. The ESC acts as the necessary electronic commutator, that’s copper and carbon in a standard brushed motor. Also speed control. To test independently you must surely use specialist substitute items. To find the overall efficiency I think we still need the accurate mechanical output figures, the whole crux of our little discussion. Eagle Tree I’m sure is a good idea, but it still only gives you the input details. I enquired about these but they don’t work to a Mac unfortunately; and at the moment there are no plans to change that.

   I would expect the motor to fail rather before the speed controller. The motor will eventually wear out, moving metal items are always going to be subject to friction, however small. Solid state electronic devices have no moving parts and in therefore in theory can last a very long time indeed. Certainly outliving the human operator. But is there possibly a little incentive to in-build a spot of obsolescence? ESC’s do seem to fail with unfailing regularity, we are back at the lack of specifications again. All the equipment that I commissioned, mechanical and electrical, had to show an ability to operate at 110% of full load for an appropriate time, usually a number of hours, until the temperature became stable and stayed within spec. This is pretty general, I would think. So I’d expect our ESC’s to be able to easily perform within, and a bit over the top, so to speak, of the stated rating, for at least a few minutes without coming to too much harm.

   I’ve had very little failure with modelling equipment in general so I guess I’ve been mighty lucky. Batteries, as always, are one black spot. And even when I’ve had the odd fault it invariably turns out to be a mechanical failure so it can be repaired anyway.

   Again, this is only my view and I suspect, as I said, everyone else might have a different version. This makes it interesting, it would probably be a bit boring if we all thought the same.
   Maybe, too, the budget items are only cheaper because of where they are sold. I’m told that within the automotive industry for instance, that some items can vary greatly in price simply because of which marque of car they are sold under. I guess it’s all relative.

   Good Flying!

   PB    

                

[Peter Beeney]

   Erfolg,
          I’m afraid I would never be able to aspire to your level of accuracy. I would only ever be within my limitations. However, I’m not entirely sure about it all being a waste of time in the real world of hobbies. I’ve been testing modellers batteries for many years, particularly tx and rx packs. From the owners point of view this just to find out their general health in terms of capacity but I’ve always treated it as a safety check so I have a firm specification and I do keep to it as accurately as possible. If this has prevented only one unnecessary crash then I consider that it’s been worth it. A far as I can see, there are indeed few standards and specifications within aeromodelling circles, is this why we seem to get a number of failures? I like to think that if my actions, with the batteries, were ever queried for any reason, I would be able to justify them.
   From where I’m standing, the ESC and motor are inseparable. The ESC acts as the necessary electronic commutator, that’s copper and carbon in a standard brushed motor. Also speed control. To test independently you must surely use specialist substitute items. To find the overall efficiency I think we still need the accurate mechanical output figures, the whole crux of our little discussion. Eagle Tree I’m sure is a good idea, but it still only gives you the input details. I enquired about these but they don’t work to a Mac unfortunately; and at the moment there are no plans to change that.

   I would expect the motor to fail rather before the speed controller. The motor will eventually wear out, moving metal items are always going to be subject to friction, however small. Solid state electronic devices have no moving parts and in therefore in theory can last a very long time indeed. Certainly outliving the human operator. But is there possibly a little incentive to in-build a spot of obsolescence? ESC’s do seem to fail with unfailing regularity, we are back at the lack of specifications again. All the equipment that I commissioned, mechanical and electrical, had to show an ability to operate at 110% of full load for an appropriate time, usually a number of hours, until the temperature became stable and stayed within spec. This is pretty general, I would think. So I’d expect our ESC’s to be able to easily perform within, and a bit over the top, so to speak, of the stated rating, for at least a few minutes without coming to too much harm.

   I’ve had very little failure with modelling equipment in general so I guess I’ve been mighty lucky. Batteries, as always, are one black spot. And even when I’ve had the odd fault it invariably turns out to be a mechanical failure so it can be repaired anyway.

   Again, this is only my view and I suspect, as I said, everyone else might have a different version. This makes it interesting, it would probably be a bit boring if we all thought the same.
   Maybe, too, the budget items are only cheaper because of where they are sold. I’m told that within the automotive industry for instance, that some items can vary greatly in price simply because of which marque of car they are sold under. I guess it’s all relative.

   Good Flying!

   PB    

                

[Peter Beeney]

   Apologies for the double post, it did that all on it’s own! I’m obviously not giving the system enough work to do!

   PB

[Simon Chaddock]

Tony

To go back to your original post losing one wire on a brush less motor is about the worst thing you can do as far as the ESC is concerned.

As you noted brushless motors have three wires so there is still an electrical circuit even when one is broken.

 

A brushless ESC is a pretty clever piece of kit and senses the rotation of the motor from the back EMF from one wire to switch the voltage to the other pair at exactly the right time to keep the motor going round. 

 

So the ESC will apply a voltage to the two remaining wires to try to get the motor started making it jerk round a bit but of course there is no back EMF from the third 'broken' wire to tell the ESC to switch over so it just keeps going and puff - magic smoke - and in an overload condition it only takes a fraction of a second.

 

I hope this helps and be careful with those motor wires!

 

 

 

 

Edited By Simon Chaddock on 05/01/2011 23:16:57

[Erfolg]

Peter

 

I do not aspire to accuracy!

 

It is a waste of time and inappropriate for modelling applications, in most cases.

 

My point is, it generally is not the cost of an item, which determines totally its failure. It is more often than not if operated within its rating and appropriately. I suspect either overloading or some operator induced failure as probable cause. In my case that has been true, more often than i really care to admit.

[Peter Beeney]

   I think you may have raised a couple of interesting points, Simon. I’m sure it wouldn’t be that difficult for the manufacturer to include an overload facility that shuts the ESC down, at least intermittently; slightly more sophisticated would be current foldback, this reduces the fault current to just a watt or so, if it’s a dead short, and doesn’t reset until the short is cleared. How about a ‘signal sense’, that shuts down when it sees an incorrect sequence? I owned an Aveox inrunner in a hotliner, this used three extra external sensing wires to the speed controller. If you disconnected any wire, motor or sensor, the ESC just shutdown, open circuit, without any overloads. This was relatively more costly though, I suppose the snag with these ideas on the standard version would be that it does makes them more expensive, possibly heavier, and only the motor would need replacing. Which is what most likely caused the short in the first place!

   The broken wire is also intriguing. Years ago a ‘safety officer’ told me my soldered joints were not strong enough for model aeroplanes and could break apart at any time. So out of interest I did some experiments on the breaking strain of wires and soldered joints. I don’t know if you’ve tried this but when you really get down to it it’s actually quite difficult to break wires, even the thin ones; and after quite a number of attempts it established that the soldered join is actually stronger than the wire. The motors seem to use the hard solid winding wire as the lead-out, and this is perhaps more susceptible to flexing, when it work hardens it soon gives up. Even so, it seems to have happened pretty quick in Tony’s case.    Was it perhaps a manufacturing fault?
   The Aveox sported soft multi-stranded lead-out wires; presumably to absorb any possible movements or small vibrations of the motor.

   Erfolg, You said it. ...not the cost of an item, which determines totally its failure. It is more often than not if operated within its rating and appropriately. I suspect either overloading or some operator induced failure as probable cause…  If you were to aspire to a spot of accuracy and in so doing kept within the rating guidelines then maybe you would find there were fewer failures, whether expensive equipment or budget toys!
   Please take no notice of me, I’m only kidding here!

   However, there might be one point. If you overload a model i/c engine, in my opinion that’s taking it past the point where the revs multiplied by the torque equals the maximum power output, that’s not the maximum revs, it would heat up a bit and run slower and the power output becomes less. Ultimate overload, it would just stop, no harm done.
   If you overload an electric motor, in my opinion that’s taking past the point where the revs multiplied by the torque equals the maximum power output, the motor slows and the power output becomes less but the current supply increases. The motor will certainly heat up. Ultimate overload, it would just stop but the current input would be at a maximum, greatest harm done.
   It certainly seems as though overloading an electric motor is something you don’t want to be doing too often!

   PB