Help with ESC's

[red zeppelin]

So during a tuning flight 2 weeks ago I noticed a small whif of smoke by one of the props, then the ESC on that arm immediately burst into flames. Thankfully I was only a foot off the ground, so no major damage.  This has led me on a search for new ESC';s though, and I have some questions.

I originally had BEC ESC';s on the craft, but now I am thinking I should get ones without that, and get a UBEC instead.  Any thoughts on the differences?  Will that possibly help cutting down the heat in the ESC?

Also, I had 30A ESC';s but I think I could probably get away with 20A instead.  I have a 450 size craft with emax motors currently.  Will 20A be sufficient?

Lastly, looking for ESC brand recommendations.  Thanks in advance for any suggestions or help.

[Cheredanine]

The amps going throu the esc, depends on:
Cell count of the battery (the voltage governs how fast the motor tries to spin)
The motors (rather more specific than brand)
The props
And to a degree how you fly

Opto ESCs are popular amongst racers since they are smaller and lighter.
I am no 450 expert (I expect you are running a conventional 2.2:1 power to weight ratio, most of my stuff runs 12 :1 up to 15:1 so can';t tell you the likely draw for a 450 rig even if your told me all the details for the above.  But the way to do it is find some static thrust test figures for the motors, props and cell count you are using. That will tell you the amp draw.

[red zeppelin]

Thanks for the pointers.  The last time I did a quick calculation based on the weight and the motors, etc. the thrust to weight was in the neighborhood of 3.8:1

I have a Turnigy 2200mAh 11.1v 3S battery, the motors are EMAX MT2213 (935 Kv); motors are listed at 835kg of thrust.  I am using 10x4.5 props.

Total weight of the craft is 879 grams (roughly).  Not sure if any of this helps or not.  Also, the motors say they are recommended for a 20A ESC but I don';t know if that matters much.

[red zeppelin]

So I went down to a 20a esc, I got ones that are pretty small, they are made by makerfire, and running the BLHeli firmware.  I didn';t update any of that, I figured the out of the box firmware would be alright for me, especially until I get flying a bit more.

So I was able to calibrate them tonight (had to use the all at once method, the mission planner version won';t work for me because of MP) and all seemed to go well.  Motor test after confirmed they are all working, had to switch two of them so they spun the correct direction, but all else seems alright.  Re-calibrated the radio and then tested it all (no props of course ;D) and it seems to be functioning fine.  Actually the throttle ramp up seems to be on a smoother curve now then before.  I am going to reassemble the frame tomorrow and hope to be back in the air in a day or two.  My last items before the esc fire were to work out the PID settings, so hopefully the new esc';s will help with stability a little as well.

Wish me luck!!

[red zeppelin]

Test flight was a success!

I still need to tune the PID a bit I think, it';s drifting a bit more than it should but it already feels more stable than it ever did with the old ESC';s.

Any advice on how to crank back the throttle a bit?  It seems very sensitive when I am making adjustments on throttle.