Esc spark and caps.

[Peter A]

Hi I was reading one of the previous threads about anti spark leads. This has brought to my attention that my esc's are no longer sparking when I plug in a battery. Are the caps dying, and can I replace them easily. Esc's are seaking 90A and turnigy 120A. Can you put bigger or more caps in. I'm figuring it is just a case of cut off the heatshrink and replace. Can I run wires out and attach new caps to them.

[wade7575]

From what I have read it would suggest that they are dying,yes you can replace them just be sure to take a picture of how the Cap's are in your ESC,the reason I suggest a piture is because alot of people do not know that Capacitor's are (Polarized) have a Positive and Negative just like a car battery and you want to make sure they are installed with the negative wire going into the hole for the negative on the ESC.

If you look at the ESC it will be clear by just looking at the Cap's and just re-install the Cap's the same way,there should be a white stripe going down the side of the Cap and I think that's the Positive wire,it really does not matter what it is just so long so long as you install the wire with the white stripe in the same hole as the old one.

If you not sure what Cap's to get just look at the value on the old ones first,the ones sold at OSE are 35 volt 1000uf,if the ones at OSE are not right just get ones that have the same Volt and UF rating and try to get Rubycon brand.

If you go with larger Cap's then what's installed on your ESC's it won't hurt the ESC but they may not fit,also just get a Cap bank from OSE and Solder the wire's coming from the Cap Bank to Power in wires on your ESC,and keep the wires coming from the Cap fairly short.

To get the old Cap's out you just need a Soldering Iron something around 30 to 40 Watt's but no more unless you really know how to Solder good as to much heat can damage the ESC really fast.

[Fluid]

The following is on the OSE store:


"WARNING: If any capacitors seem to bulge, start to deform, leak or pop, stop using them IMMEDIATELY!!! If Capacitors fail they can explode and cause injury.

It is generally reported that capacitor failures can be attributed to:
1) Heating, causing a capacitor to swell and explode.
2) Drying of the liquid electrolytic inside from various causes, such as defects, leaking and even cleaning.
3) Capacitors re-form over time to meet a usual and expected voltage. Surges that are not normal can cause sudden failure.
4) The older they get the greater the incidence of failure.
5)High-current motor setup will tend to kill the caps quickly (because of the large voltage changes)."

Removing the exiting caps is easy - on most you can just grab the cap with pliers and twist it off the board - or use a soldering iron carefully. The easiest solution is to add a cap bank. Watch the polarity!


.

[Peter A]

Thanks guys, I cut off the heatshrink last night, only one connection will be tricky. I'll have to remove one of the power in wires for acess. I think I'll solder in some short wires and bring the caps out so I can replace easy again. I can fit bigger caps then if that is the case. The existing ones are 35v 390uf Rubicon.

[Peter A]

I have been able to get some new caps. The only one with the right uf are panasonic. The local electronics shop said that you have to use the same uf. Can anyone confirm this? Thanks.

[viper1]

This thread raised a question I have now;

How will I know my caps are near their 'end of life' besides the lack of spark when connecting the batteries?
I'm asking because I don't have a spark when connecting as I have mounted a bypass with resistor in the positive line.
Any other symptoms of dying capacitors?

[egneg]

This thread raised a question I have now;

How will I know my caps are near their 'end of life' besides the lack of spark when connecting the batteries?
I'm asking because I don't have a spark when connecting as I have mounted a bypass with resistor in the positive line.
Any other symptoms of dying capacitors?

If they are bulged out and/or leaking on the ends.

[viper1]

Ok clear, thanks !

[tlandauer]

If they are bulged out and/or leaking on the ends.

I check them after every run and I try to look at them at different angle just to make sure their ends are flat, sometimes when they bulge just a little, it is still hard to see.
Here is my question: If they are near the end of their service life but have not bulged, do we only judge their condition by if there is spark or no spark?

[capnswanny]

Visual inspection is your best first bet to catch a faulty component (capacitors, resistors, transformers, diodes, etc.)

At work we have test equipment that can read the capacitor 'in-circuit', but it is quite expensive (http://huntron.com/products/2800.htm). In my experience (22yrs Electronics Tech, US Navy) the only other way to absolutely verify the component is to remove it from the circuit to test it with a tester....not a good option. I know of no other way to determine health of your capacitor.

The spark we see at plug in is a good indicator that the capacitor is charging up. If we don't see a spark, odds are good that the Cap is not functioning properly. And although this method of determining Cap health is far from ideal, it is fast and convenient.

Peter, as far as matching uF, close is good > or =. In general you shoot for a matching voltage rating or greater, and matching Farads or greater. Bigger is not always better as it can load the system and degrade performance, smaller can be ineffective or fry.
The MFGR of the ESC's likely spent some time determining the optimal component for the circuit. With home electronics (non-RF related) I tend to shoot for replacements in the range.
There are guys out there with way more experience on this subject...I would love to hear from them on this...

Corey

I check them after every run and I try to look at them at different angle just to make sure their ends are flat, sometimes when they bulge just a little, it is still hard to see.
Here is my question: If they are near the end of their service life but have not bulged, do we only judge their condition by if there is spark or no spark?

[tlandauer]

Thank you for the insightful info., CAPNSWANNY !

[Peter A]

Thanks for the info capnswanny. I'm going to replace withsame v and uf. I also want to bring some wires off the board to conncet the caps to. Any issues with doing this that anyone would know?

[Peter A]

Good news, i've replaced caps on one of my esc's, spark again! Will do the other tomorrow and run on Sunday. Not too difficult a job, and i just put them back on the same, didn't use wires.