Warm ESC

Just a quickie - still setting up my 250 heli build, and noticed the other night that the ESC was warm to the touch (not hot - just warm) after a few minutes of using the BEC to fiddle with Servo's. Motor was disconnected for safety while I was sorting out mechanical pitch adjustment.
I'v not noticed this on my 450, and wondered if this was the norm?
Cheers for the help gang!

It depends on the specific type of ESC, but normally, a bit of heat is normal. Most ESC's have a linear BEC inside them. You probably know, but the pack voltage connected to the ESC will be between 9-12.6v for a 3s lipo pack connected to it. However, the rx and servos, ideally want a voltage of 5v. In order to step this down, a linear BEC basically dissipates the excess voltage, as heat.

The formula for working out how much, is pretty simple, You just take the current being drawn by the load (say 1Amp) and multiply it by the voltage drop required (so call it 7v for a nearly fully charged 3s pack). That equals 7 watts of power being dissipated by the BEC, and is enough to warm stuff up quite quickly.

The general rule of thumb I use, is that if an ESC, BEC, or Voltage regulator is too hot to hold your index finger on for more than about 5 seconds (about 70°C or so) , it is being over-worked, and you need to do something about it.

If it does get too hot, then the easiest (and neatest) way around it, is to install an ESC that has a "Switching" BEC. These drop the voltage by switching it on and off very quickly, making it appear like a lower voltage on average. They waste far less power, and as a result don't tend to get anywhere near as warm.

HTH, and sorry for rambling on. I did try to cut the xplanation right down, but it is hard, I hate giving half an answer

Andy

It would be either ans or wer if you did Andy

When they sit on a bench connected they do tend to get hot but after a flight it should run cooler.
The closer you run the esc to 100% generally the cooler they run.
I've found that most esc's especially Align ones run cooler above 70%.
I tend to run them between 90 and 100% all the time and they stay cooler that way.
The ones I like most are the Kontronik range.They run cool all the time,awesome governor and huge prices to match.
The ICE range look good too.
Andy how's the ICE so far?Are you liking it?

Danny.

Yep, the Castle ICE is running great. Only slightly warm to the touch after a flight in the Jibe, and that is with no cooling airflow at all. I've not messed around with the datalogging onboard yet though, been a bit busy the last few weeks

BY the way, Danny is talking about switching losses in the main FETs on an ESC. They are the bad boys that turn the power on and off quickly to control the speed (power) of the motor. Because they don't turn on and of instantly, and have a slight resistance (that varies with how fast they switch), they disspiate power too, and therefore get warm too...

Andy