ESC: Electrolyt Capacitor Blow Up? Why?

[jlagran Heli]

Hi... :)
I got experience using ESC (electronic speed controller):
1. Futaba ESC for my Kyosho Heli EP, the Capacitor ---||---- is blow up.
2. Phoenix 35 BL, the Capasitor also Blow Up, during running at full speed for a while or brake maybe.
3. JETI BL ESC also the same.

I try to change the C with the same value, but then burnt again.(470uF/16V).

The question are: :confused:

1. What is that C function on ESC?
2. Is the C always placed between Batt + and Batt - at ESC?
3. Can I change the value of the C? is bigger uF is better? or bigger V better?
4. Is it save to run model without C in its ESC?

Please Help :o

[william541]

A1. The C is there to provide a stiff DC supply to the switching devices, usually FETs.

A2. This is usually the case, the closer to the switching transistors, the better.

A3. Yes & No. In this application, you need a C with a very low ESR (Equivelent Series Resistance) and also a high ripple current rating. If these two items are not properly matched to the application, then poof! Not to mention the voltage rating, typically they are sized at least 2X the supply voltage. The actual capacitance value in this application is usually chosen to get the lowest ESR and provide enough current fill to supply the ESC during high peak switching currents. This smooths the current load on the battery so it can breath easier.

A4. No it is not safe unless you want to see how long the ESC will survive without them. I suspect the reason you may be having these units go out is because of the excess resistance in your battery or battery leads. Or perhaps they were sized improperly to begin with. Then too, electrolytics also have a finite lifespan usually rated in hours (~2000 hrs typically). The more you abuse them, the shorter life they will have.

Sorry to ramble, but that is my 2 cents worth. Hope it helps. -Bill-

[Andy W]

How long are the leads between your battery and ESC?

[Ron van Sommeren]

Elco's have polarity. Did you solder (+) to (+) and (-) to (-) ? If not ... sizzzzzzzzzzzzle/pouf.

Too long leads make life hard on elco's too. If that's the case, you need extra elco's somewhere halfway.

Vriendelijke groeten ;) Ron
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[Dan Baldwin]

How many cells, and what type of battery are you using?

Dan

[ImaBiggles]

pouf.



It that Dutch for poof? :D

[K Quist]

If your ESC is getting very hot when you are flying the electrolytic cap will be hot too, and this reduces the lifttime. So try to have the ESC well cooled and change the el-cap to 105degC type instead of the commonly used 85degC

[jlagran Heli]

Wow..

Thanks for replies.

@ Wiliem541::
- Wow I thought C only have uF and V only.. ( ESR ?)
- Well I Think I'll replace with bigger uF C, I am correct?, I think it's difficult to find C with thoose specific ESR and ripple (?)

@ AndyW::
- lead Batt to ESC about 20 cm? I didn't cut the wire as factory default. Is it to long?

[jlagran Heli]

Elco's have polarity. Did you solder (+) to (+) and (-) to (-) ? If not ... sizzzzzzzzzzzzle/pouf.

Too long leads make life hard on elco's too. If that's the case, you need extra elco's somewhere halfway.


Yeah I know + to + , - to -

Extra elco;s half way? wow I'll try that, can it be placed in the banana jack or tamiya jack?

[jlagran Heli]

@Dan Baldwin::
1. Futaba ESC 6 or 8 cells NiCd 2400mAH
2. Phoenix 35 BL, the same
3. JETI BL ESC 12 cells NiCd 2400mAH

@K-Quist::
Oh, yes, maybe so. It was too hot, I'll try higher temp capabilities elcos.
Where can I fing thoose kind of elco's ? Digikey? RadioShack?
I thought elco's properties only uF and V, mmm... need to learn more ha ha...

Or are there any voltage/current feed back from Motor to ESC?
You know just like generator, the motor running act like generator (off throttle model
moving, motor turning), generating current
and back to ESC then burnt the elco's?

Just thought???

[Dan Baldwin]

Yeah I know + to + , - to -

Extra elco;s half way? wow I'll try that, can it be placed in the banana jack or tamiya jack?

Banana jack???? Tamiya jack??? I think I see your problem.


Dan

[E_ferret]

@Dan Baldwin::
1. Futaba ESC 6 or 8 cells NiCd 2400mAH
2. Phoenix 35 BL, the same
3. JETI BL ESC 12 cells NiCd 2400mAH


Where can I fing thoose kind of elco's ? Digikey? RadioShack?
I thought elco's properties only uF and V, mmm... need to learn more ha ha...




Try the Rubicon ZL series, ultra low impedance, high ripple, 105 degrees C.

For a supplier near you, try Farnell (Australia, Hong Kong, Singapore, or Malaysia )

eg. 50V DC, 470 mF, 910 mA ripple, impedence 0.043 ESR part no. 761-886
or 50V DC, 330 mF, 910 mA ripple, impedence 0.043 ESR, part no. 761-874
0r 50V DC, 1000mF, 1650 mA, 0.024 ESR, part no. 761-898

There are others too.

regards,

[jlagran Heli]

Thanks Guys....
Banana - Tamiya will be changed to Dean ??

Thanks E ferret, I'll try that.

[Dan Baldwin]

The banana plugs may or may not be a problem. High quality banana plugs have a fairly low resistance, but low quality or loose fitting banana plugs have a high resistance. Tamiya connectors should never be used IMHO. They have a high resistance, and tend to fail, especially at high current. Deans ultra connectors would be fine, or Sermos.

Dan

[Takao Shimizu]

I have a lot of experience of hot capacitor on the power line.
Just replace to High-Ripple Cap. and increase the RPM to get more motor efficiency to reduce charge-discharge current balance on the PWR line.

http://www.rcgroups.com/forums/showpost.php?p=3824043&postcount=1067

Takao