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ESC Failure - What went wrong?

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Old 07-10-2013, 05:09 PM
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PeterP
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Default ESC Failure - What went wrong?


Hi,

I am looking for any explanations why a ESC failed in my F3A trainer model which has resulted in a fried ESC, receiver and servos. I am not sure what happened only that when I connected my main battery to the ESC it started to smoke. This setup has been performing faultlessly for the past 12 months without a hint of any problems. I simply connected as I always do with the same batteries.

Unfortunately the damage went beyond the ESC and it took out all the servos and receiver at the same time. I think I will stick with the opto style of ESC in future to limit the damage should this happen again. Expensive lesson Futaba reciever and digital servos all round.

The ESC was a Hacher X-70-SB-Pro.

Any suggestions for a good quality 6S ESC which can provide a level of isolation between it and the receiver.

Thx in advance


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Old 07-10-2013, 07:17 PM
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Jason Arnold
 
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Default RE: ESC Failure - What went wrong?


Quote:
ORIGINAL: PeterP


Hi,

I am looking for any explanations why a ESC failed in my F3A trainer model which has resulted in a fried ESC, receiver and servos. I am not sure what happened only that when I connected my main battery to the ESC it started to smoke. This setup has been performing faultlessly for the past 12 months without a hint of any problems. I simply connected as I always do with the same batteries.

Unfortunately the damage went beyond the ESC and it took out all the servos and receiver at the same time. I think I will stick with the opto style of ESC in future to limit the damage should this happen again. Expensive lesson Futaba reciever and digital servos all round.

The ESC was a Hacher X-70-SB-Pro.

Any suggestions for a good quality 6S ESC which can provide a level of isolation between it and the receiver.

Thx in advance


Hi Peter,

Perhaps you should mention what motor and prop are being used?

Did the servos and Rx smoke too or just no longer work?

Cheers,
Jason.
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Old 07-10-2013, 08:11 PM
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Default RE: ESC Failure - What went wrong?

Hi Jason,

Motor is a Hacker not sure exact but it is an A16XX series 1. Prop is APC 16x10E

Some of the servos smoked not sure about receiver as there was plenty of smoke around at the time so not sure. either way receiver is dead. The ESC failed and basically put 22 volts onto the receiver bus and the reset is history. I don't think I will bother using a ESC with a BEC in future. In hindsight I should have snipped the positive wire from ESC to throttle channel before using it to ensure this would not happen either though I wasnt using the BEC feature in the ESC.  
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Old 07-10-2013, 08:38 PM
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Default RE: ESC Failure - What went wrong?

Hi Peter,

The reason I ask is that recently a fellow club member put an ammeter on his Mythos with 8S. I was astounded to see the thing drawing >115A from the flight pack! On 6S the current was ~80A. He was using a Jeti Spin 99 so the ESC could handle the current. Your 70A ESC may be marginal. Have you ever checked the current being consumed?

Cheers,
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Old 07-10-2013, 09:28 PM
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Default RE: ESC Failure - What went wrong?

I would look for wire damage to see if there was a possible short. Could be external or internal to the ESC.
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Old 07-11-2013, 12:27 AM
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Default RE: ESC Failure - What went wrong?

Hi,

There is a CSM "BECSafe" that can prevent high voltage going to receiver if BEC fail:
http://www.rcmodels.org/csm/throttlesafe.html#becsafe

I suppose the high end ESC's with built in BEC have some sort of solutuion to this problem also.

I use Castle Creations Phoenix ICE 100 ESC with BEC in my old Sebart Wind S 50E and it has worked fine well over 700 flights with that setup and 6 cell LiPo. ICE 100 was not among the Castle ESC's that had recall some years ago.
Not sure if ICE 100 (or it's never version Edge 100) has overvoltage protection if BEC fail.

I use in my Sebart MythoS 125E a Jeti Master Mezon ESC with BEC and Scorpion Backup Guard (against BEC fail that give low or no voltage to receiver) but what happen if BEC in a Mezon ESC fail in a way that it could send high voltage directly to receiver I do not know.

It is an interesting subject - what ESC's has high voltage protection that will shut off BEC so no (high) voltage will reach receiver (and servos).You need something like a Backup Guard to save the plane in such case.

/Bo
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Old 07-11-2013, 12:55 PM
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Default RE: ESC Failure - What went wrong?


Quote:
ORIGINAL: bem

Hi,

There is a CSM ''BECSafe'' that can prevent high voltage going to receiver if BEC fail:
http://<font color=''#0000ff''>http:...becsafe</font>

I suppose the high end ESC's with built in BEC have some sort of solutuion to this problem also.

I use Castle Creations Phoenix ICE 100 ESC with BEC in my old Sebart Wind S 50E and it has worked fine well over 700 flights with that setup and 6 cell LiPo. ICE 100 was not among the Castle ESC's that had recall some years ago.
Not sure if ICE 100 (or it's never version Edge 100) has overvoltage protection if BEC fail.

I use in my Sebart MythoS 125E a Jeti Master Mezon ESC with BEC and Scorpion Backup Guard (against BEC fail that give low or no voltage to receiver) but what happen if BEC in a Mezon ESC fail in a way that it could send high voltage directly to receiver I do not know.

It is an interesting subject - what ESC's has high voltage protection that will shut off BEC so no (high) voltage will reach receiver (and servos).You need something like a Backup Guard to save the plane in such case.

/Bo
When I saw the existence of the CSM BECSafe I became worried about failures resulting in high voltage being delivered to the receiver. I then heard that CC was adding circuitry to prevent these kinds of failures. Then I emailed Jeti. I was assured by Jeti that all of their BECs and voltage regulators had circuits to prevent failures that resulted in high voltage at the output.
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Old 07-11-2013, 02:18 PM
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Default RE: ESC Failure - What went wrong?

Hi Peter,

Can't help you with the original question but just maybe you could run a linear BEC type regulator between the BEC output of the ESC and the RX, with the ESC BEC set to about 1-2V higher than the linear BEC output.

This would stop the rest of the electronics from being fried if the ESC BEC supplied full voltage, but the linear BEC would overheat and shut down pretty quick, so you probably lose the plane anyway if it were in the air.

Other than a 4 (or 5) cell ni-cd pack and switch, we're pretty much stuck with having to rely on some type of regulator on "older" Futaba stuff.

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