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Old 02-06-2015, 10:56 AM   #1
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Default Learn me about "power-capacitors"

Hi everyone,
I'm using older Novak GTB esc's that have treated me well for many years. Currently I'm having problems fitting one of them under a very low profile body and the main culprit is the keg of a single power-cap that is stock on this unit. I've searched but there doesn't seem to be much discussion about changing these out, even though there are many replacement choices in the aftermarket.

The question is this - if I match the voltage and uf of the current "keg", am I ok changing to any of the smaller, multi-cap banks out there?
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Old 02-06-2015, 11:15 AM   #2
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You'll also need to use a capacitor that has an equal or greater ripple current rating. If making your own bank, use a type that is called "high ripple current" or something similar. If the cap is already made for an ESC, then it is this type.
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Old 02-06-2015, 04:42 PM   #3
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Quote:
Originally Posted by Davidka View Post
Hi everyone,
I'm using older Novak GTB esc's that have treated me well for many years. Currently I'm having problems fitting one of them under a very low profile body and the main culprit is the keg of a single power-cap that is stock on this unit. I've searched but there doesn't seem to be much discussion about changing these out, even though there are many replacement choices in the aftermarket.

The question is this - if I match the voltage and uf of the current "keg", am I ok changing to any of the smaller, multi-cap banks out there?
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Originally Posted by howardcano View Post
You'll also need to use a capacitor that has an equal or greater ripple current rating. If making your own bank, use a type that is called "high ripple current" or something similar. If the cap is already made for an ESC, then it is this type.
In laymen's terms....yes
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Old 02-06-2015, 06:52 PM   #4
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I once had a discussion with a Novak engineer and whet he told me is that the Cap had to be of low ESR type ( equivalent serial resistance, I think).
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Old 02-07-2015, 03:09 AM   #5
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I once had a discussion with a Novak engineer and whet he told me is that the Cap had to be of low ESR type ( equivalent serial resistance, I think).
Lower ESR gives higher ripple current capability. While it's not absolutely necessary, using low-ESR capacitors helps keep the physical size smaller while giving the ESR required by the ESC.

Other ways to decrease the total ESR and give higher ripple current capability are using capacitors with higher voltage rating or higher capacitance.

Also, using several smaller capacitors with the same total capacitance as one single capacitor will increase the ripple current rating, since they have more surface area to dissipate heat, and the heat has a shorter path to get from inside to the outside.

Again, if replacing an ESC power cap with another made for the purpose, all of the above is already taken into account. But I have included the info as a response to the title of this thread.
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Last edited by howardcano; 02-07-2015 at 03:39 AM.
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Old 02-07-2015, 06:28 AM   #6
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There is some good info in this thread.

Another thing to consider is that capacitors "age"; that is, they degrade with use (and sometimes with storage). Replacement is advised on some sort of regular basis, since RC power systems are downright abusive to these components.
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Old 02-07-2015, 07:48 AM   #7
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Another thing to consider is how much power you are drawing. I know with a Tekin RS Pro, you are OK to use just the one provided cap down to an 8.5 turn motor. Any lower, it's suggested you add a second cap.
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Old 02-07-2015, 02:10 PM   #8
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Default esc power cap thread

Here is a link to a thread I started about this topic about 18 months ago.
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