Dodgy ESCs

[Hai-Lee]

I have been involved in a lot of Foamy rebuilds and repairs of late and on a previous thread I mentioned that I had determined that a number of the crashed aircraft had been downed by ESCs that were shutting down the BEC due to high temperature. Well swapping out or replacing a number of heat sensitive ESCs left me with a number of ESCs that were effectively useless or even dangerous to use.

What to do with them?

Well I now DERATE them and put them back into service. So far this has been very effective and the ESCs thus used have proven to be very reliable. As an example I recently got around to finishing my Tubby Cubby and wanted an ESC to push the motor I was using to its limits, I chose an old 25A ESC which had caused a number of crashes when driving its original maximum current load of 25A but in this installation it would only need to supply 15A.

The dodgy ESC is performing excellently in its new installation and so now I have a bag of used ESCs that will not be used as landfill.

Two lessons learned! Firstly manufacturers often fit ESCs that are operating at close to or in excess of their maximum rating and the second is that old or dodgy ESCs can perform happily in a more conservative installation. Do not throw them out! Recycle them!

Have fun!

 

[Namactual]

Great advice.
I use them for testing as well. Use them for running thrust test rigs and the like.

I had the same issue with a lot of my cheap “brand” PnP kits I would buy. It’s not the ESC that I do not trust, it’s the on board BEC that always seemed to cause my problems. I have been using standalone BEC’s and bypassing the internal. As a side effect, my ESC’s do not get nearly as hot pulling the same wattage. I was really surprised how cool my ESC’s were after I bypassed the internal BEC.

The downside is the extra cost and wiring of course.

 

[Bricks]

You have discovered the reason many newbies have crashes using cheap ESC`s and then of course the radio system gets the blame. Not saying there is not a place for the cheaper equipment just in the right situation as you have discovered........ WELL done

 

[quorneng]

In my experience for reliable performance ESCs need positive cooling. It really doesn't matter how much air you blow over them the good insulation properties of the thick heat shrink means that 'warm' on the outside indicates the innards are already hot!
My solution, particularly for EDFs is to remove the heat shrink and replace the original flat heat sink with a 'fingered' one that sits in the external airflow. In such an installation a fingered heat sink is capable of dissipating the same quantity of heat at a much lower temperature.
The fingered heat sink on a cheap 30A ESC on my 55 mm EDF Fairey FD2

At full power the EDF draws about 28 A. I am sure that 30A ESC would have caused much trouble without the benefit of that super efficient heat sink.

 

[rockyboy]

I tend to just put larger ESCs in to start with - and if one comes down hot, I move up to the next bigger sized ESC. So for something expected to draw 28A I'd run a 40amp ESC