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Old Sep 26, 2012, 02:44 PM
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ESC capacitors blown during manual programing!

I just hooked up a Red Brick 125a ESC to check its operation before installing in a plane. 6s battery, 90mm change sun fan with 1600kv factory motor (previously balanced and working normally). There was a little stuttering or roughness around half throttle so I began programming the ESC settings manually to suit the outrunner motor. After setting a couple parameters two loud pops or snaps were made by the ESC. Two of the three large capacitors were bulged discharging a brown liquid out the ends. All connections to the battery and motor were correct and no chance of a short.

Anyone have an idea what would cause the caps to fail with so little running time?

Thanks Eric
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Old Sep 26, 2012, 02:54 PM
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Two things will make electrolytic capacitors fail in that way, over voltage or reverse polarity.

Larry
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Old Sep 26, 2012, 03:16 PM
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I'm thinking the caps may have been installed reversed from the factory. The battery and motor leads were short (just the length that came with the ESC and normal motor wires) and the 6S battery is within the normal 7S rating of this ESC. I have more than half a dozen of these Red Bricks. Most are doing a fine job but I have had about a 25% failure rate. I'm pushing a couple on 7S in the 100A range without overheating.
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Old Sep 26, 2012, 03:24 PM
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Hi Eric,

In my experience, caps tend to get hot when programming the ESC.
I avoid this by programming the ESC with only a 2S battery connected.

Regards, Jan.
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Old Sep 26, 2012, 03:29 PM
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I have programmed, and reprogrammed many of this same type of ESC and never had such a failure. I wasn't programming for any great length of time and the ESC hadn't performed under any load to heat up first.
I think I will cut it open to check the polarity of the caps compared to my other ESC's.
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Old Sep 26, 2012, 05:33 PM
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Quote:
Originally Posted by 4stripes View Post
6s battery, 90mm change sun fan with 1600kv factory motor (previously balanced and working normally). There was a little stuttering or roughness around half throttle so I began programming the ESC settings manually to suit the outrunner motor. After setting a couple parameters two loud pops or snaps were made by the ESC.
Cheap ESC, high Kv motor, high voltage.

Several incidents have been reported of cheap ESCs blowing up during programming when using high voltage. I suspect the problem is that the pulses sent to the motor (to create the 'beeping' sounds) are too long, causing excessively high current spikes. This is more likely to occur with a high Kv motor because it has low inductance. Inductance is the the only thing that stops the current from instantly jumping up to hundreds of amps with a high voltage battery.
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Old Sep 26, 2012, 05:54 PM
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Originally Posted by 4stripes View Post
I think I will cut it open to check the polarity of the caps compared to my other ESC's.
Don't bother. If the polarity was reversed they would have blown immediately upon connecting the battery.

Larry
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Old Sep 26, 2012, 08:34 PM
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Thanks for your quick and helpful replies everyone!
Perhaps I was just "lucky" with my previous programming. In future I will use a 2S battery for any programming of the ESC to reduce stress on the caps.
Cheers Eric
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Old Sep 26, 2012, 09:10 PM
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Originally Posted by Lnagel View Post
Don't bother. If the polarity was reversed they would have blown immediately upon connecting the battery.

Larry
Indeed, makes quite a nice bang too, nothing ambiguous there.

Caps were most likely dud, or fake and lying about their voltage ratings.
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Old Sep 27, 2012, 12:22 PM
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I took the shrink wrap off the ESC and found the heat sink was in contact with the motor leads...
Nice!
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Old Sep 27, 2012, 02:31 PM
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Lame, Hobby King.

mw
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Old Sep 28, 2012, 12:33 PM
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Originally Posted by pompebled View Post
Hi Eric,

In my experience, caps tend to get hot when programming the ESC.
I avoid this by programming the ESC with only a 2S battery connected.

Regards, Jan.
Very interesting. All the ESC's i have taken apart has the caps wired directly across the input wires, so there is no peak draw on the caps at all. I think they soldered on the Caps the wrong way round on OP's ESC.

I can't see why the caps should ever get warm - are you sure that it's not the rest of the electronics that heats up ? that's much more plausible.

// Per.
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Old Sep 28, 2012, 12:38 PM
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Originally Posted by Lnagel View Post
Don't bother. If the polarity was reversed they would have blown immediately upon connecting the battery.

Larry
Nope. I have seen several boards with reverse-wired caps where absolutely NOTHING happened, but who knows for how long... I have seen reverse-wired caps that blew up in a couple of days operation too, and then there's the surprise when you just power up a new board you made, stick your head over the board and BANG

// Per (Worked in the Electronics industry last 12 years)
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Old Oct 07, 2012, 11:41 AM
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Caps type, make and polarity in
Too long battery wires will kill ESC - RCG

Vriendelijke groeten Ron
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Old Oct 07, 2012, 03:24 PM
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Since few industrial ESC companies ever used to say programing while running a motor was recommended.

I would & did ALWAYS reprogram with the motor disconnected.

Your description sounds like the parameters you were playing with DID SEND RANDOM out of phase / sequence pulses to the motor windings. That will cause massive out of time /phase spikes to be reflected back to the ESC control section & reflect back to the battery leads

. Remember a motor CAN become a generator when it has a PM ( permanant magnet ) in it.

Remember..........We are NOT BUYING industrial quality ESCs!!

Never program with a motor connected. Does that statement prevent the problem ?
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