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-   -   ESC Capacitors (https://www.rctech.net/forum/radio-electronics/991963-esc-capacitors.html)

RsA89 07-09-2017 09:36 AM

ESC Capacitors
 
Does it make a difference to go to 1 to 2 or 4 capacitors? I'll be running a 2wd buggy 17.5. Is it worth upgrading and would I even notice a difference or performance gain?

Roelof 07-09-2017 10:20 AM

Did you know this forum has a search function? You will be amazed what you can find about "capacitor"......

In many topics you will read the capacitor is no performance part. More smaller ones is just to lower the internal resistance and the size but the value is determed by the designers of the ESC and it is not wise to change it.

RsA89 07-09-2017 03:16 PM

Yes I know there is a search feature. I tried and didnt find my answer. My question, is there a performance gain you can notice?
Hobbywing offers an upgrade, for their Esc they make.

From Hobbywing website
This capacitor module (/cappack) is for “upgrading” your car ESC. With this cappack, the start-up acceleration of your vehicle will be greatly improved. Besides, the great ripple current endurance significantly reduces the generated interference due to the rapid ON/OFF of the ESC power tube.

tbrymer 07-09-2017 04:45 PM

I've used the single and double on my xr10 pro stock and didn't notice a performance increase.

Andy Koback 07-09-2017 05:51 PM


Originally Posted by RsA89 (Post 14971940)
Yes I know there is a search feature. I tried and didnt find my answer. My question, is there a performance gain you can notice?
Hobbywing offers an upgrade, for their Esc they make.

From Hobbywing website
This capacitor module (/cappack) is for “upgrading” your car ESC. With this cappack, the start-up acceleration of your vehicle will be greatly improved. Besides, the great ripple current endurance significantly reduces the generated interference due to the rapid ON/OFF of the ESC power tube.

Just a sales pitch. Stick with the stock one and you'll be fine.

disaster999 07-10-2017 12:45 AM


Originally Posted by Andy Koback (Post 14972061)
Just a sales pitch. Stick with the stock one and you'll be fine.

Not entirely true. Stock ones do work fine but some caps will provide slight better performance than others.

Check out this video
https://www.youtube.com/watch?v=R3V0Uj0EnBo

Roelof 07-10-2017 01:14 AM

Thats a crap video!

Yes, it shows the differences of the internal resistance but it does not show the end result on the ESC performance.

disaster999 07-10-2017 02:10 AM

He did have some good points in the video. He did say that not all caps are created equal and ones with higher internal resistance would affect the charging and discharge of the cap. He also did repeatedly say that any of the commercially available capacitors would not magically improve performance of the ESC. The only thing that could would be your battery. The capacitors are only there to smooth out the pulses caused by a brushless system.

If you really want real performance gains, look into supercapacitors. They have a much higher capacitance in them which allows it to store a lot more energy and can store and release that energy much faster than regular electrolytic capacitors. Basically like a rechargeable battery on steroids. The higher capacitance and the ability to charge and discharge faster will give the illusion of it providing more "power" as the voltage doesnt drop as much under load. I can definitely feel the difference with it on the track.
https://www.youtube.com/watch?v=_CfU_roIvuI

Not sure how legal they are in sanctioned races tho.

howardcano 07-10-2017 06:33 AM

The BRL limits capacitors to 10000uF. I believe ROAR does the same; that would make sense since the BRL organizer is also on ROAR's executive committee.

ta_man 07-13-2017 01:08 PM


Originally Posted by disaster999 (Post 14972268)
If you really want real performance gains, look into supercapacitors. They have a much higher capacitance in them which allows it to store a lot more energy and can store and release that energy much faster than regular electrolytic capacitors.

Supercapacitors have much higher internal resistance that typical electrolytic capacitors and cannot release their energy faster.

tvih 07-15-2017 03:17 PM

Since it's somewhat related, I guess I could post here rather than make a new thread...

My Novak Havoc SC Pro blew its capacitor because of an engine failure (and resulting user failure, doh). The stock one seems to be 5600uF/10V. Of course with Novak being out of business nowadays there's no direct replacement, and all the ones available at my local RC shop seem to be waaaay lower in uF rating and/or different voltage, and I'm not sure if they'd fit the bill so to speak.

The Havoc was in my SC10 4x4, but I bought a new combo for that and rather than scrap or sell the Havoc I am thinking of doing some other switcharounds with my cars, and maybe put this Havoc on my 2wd SC10 - on the 4x4 it started cutting off throttle way too soon even with plenty of voltage left (possibly the cap might've been already failing and causing that in part though?), but with the 2wd it'd be driving a Speed Passion 540 7.5t / 5100kv motor rather than the Havok Kinetic 550 4.5t 4700kv which is now in pieces and I don't have the knowhow to repair it even if possible. At any rate the stress on the ESC should be way lower with the 2wd setup, so I guess a weaker cap might be enough? I suppose I could alternatively search electronics stores for more similar replacements.

ta_man 07-15-2017 08:52 PM

You can find capacitors with those specs on Digikey. Make sure you select Low ESR.

Roelof 07-16-2017 01:31 AM

A capacitor is just a standard electronic component, much better to visit the local radio shack.

tvih 07-16-2017 08:28 AM

Well, aren't I the lucky bugger. Now another ESC, Speed Passion Reventon Pro 1.1, tried to fry itself. To what extent it was successful at it, I'm not sure. I'm unsure of even testing it properly - the capacitor bank (4x 16V 470uF caps) was extremely hot, way too hot to touch even for a fraction of a second, but even so I can't tell if the capacitor bank is burned or not to facilitate safer testing. Doesn't smell like smoke and no external signs of damage on the cap bank other than the heat peeling off the protective plastic shrink wrap (as in it tore itself off by shrinking further). The ESC itself has a smoke-y odor even though it does still give power and removing the bottom of the case reveals no obvious burn marks on the circuit board.

I suppose it'd be the safest bet to replace it just in case? Since I'm going to try to find a new cap tomorrow from an electronics store for the Novak, could just as well get a second one for this while at it. Probably just gonna go with single bigger cap though.


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