2LikesEsc capacitors in stock racing good or bad?
08-18-2015 | 10:15 AM
#1
Esc capacitors in stock racing good or bad?
My question is this. Do we really need caps on esc's? Do they do more harm then good? I had a very interesting conversation with a friend who just got back from the ROAR Nats last week. He said none of the fast guys running stock had caps on there esc's. He also spoke with a very well known rep for one of the leading esc manufacturers that said the caps really are not needed and in fact the esc is bether with out them because they produce dirty power. So what are your thoughts on this topic?
08-18-2015 | 10:45 AM
#2
Tech Lord
Joined: Aug 2007
Posts: 14,052
From: Holland
The cap is not for the power but to save the ESC.
Several functions are done with the caps:
- filtering out the high frequencies of the swtiching ESC
- filtering out voltage peaks produced by induction on the wires and motor coils.
- take the high current peaks to prevent the voltage drop goes to low and with that keeping the voltage on a better level so the FET's are getting enough to get fully opened.
With no caps it is known the ESC can produce more heat which is not good for its life.
Several functions are done with the caps:
- filtering out the high frequencies of the swtiching ESC
- filtering out voltage peaks produced by induction on the wires and motor coils.
- take the high current peaks to prevent the voltage drop goes to low and with that keeping the voltage on a better level so the FET's are getting enough to get fully opened.
With no caps it is known the ESC can produce more heat which is not good for its life.
08-18-2015 | 04:41 PM
#3
What Roelof said. They make ZERO difference in laptimes despite what some manufacturers claim. They are either lying outright with their bogus marketing claims or they tested it on a speedo so crappy that it somehow actually made a difference. They will provide cooler speedo temps and improve reliability especially for mod so you should still run one but the stock OEM cap is usually just fine.
08-19-2015 | 02:21 AM
#5
Tech Lord
Joined: Aug 2007
Posts: 14,052
From: Holland
A cap is a cap, why would you ever buy an overpriced cap from a RC company with mostly too small and too long wires?
Searching for low ESR caps at the local radioshack or else online at Mouser will give plenty of options for very low prices.
Punch is sometimes noticeable, it is depending the specs/quality of the batteries. And then it is not about that it is acting as a power bank but to prevent high voltage drops so the FETS will stay working correctly.
Searching for low ESR caps at the local radioshack or else online at Mouser will give plenty of options for very low prices.
Punch is sometimes noticeable, it is depending the specs/quality of the batteries. And then it is not about that it is acting as a power bank but to prevent high voltage drops so the FETS will stay working correctly.
08-19-2015 | 08:58 AM
#6
Tech Fanatic
iTrader: (32)
Joined: Mar 2007
Posts: 909
The cap is not for the power but to save the ESC.
Several functions are done with the caps:
- filtering out the high frequencies of the swtiching ESC
- filtering out voltage peaks produced by induction on the wires and motor coils.
- take the high current peaks to prevent the voltage drop goes to low and with that keeping the voltage on a better level so the FET's are getting enough to get fully opened.
With no caps it is known the ESC can produce more heat which is not good for its life.
Several functions are done with the caps:
- filtering out the high frequencies of the swtiching ESC
- filtering out voltage peaks produced by induction on the wires and motor coils.
- take the high current peaks to prevent the voltage drop goes to low and with that keeping the voltage on a better level so the FET's are getting enough to get fully opened.
With no caps it is known the ESC can produce more heat which is not good for its life.
Is there a need to replace the capacitors in order to guarantee the capacitor performance??
08-19-2015 | 09:50 AM
#7
Tech Lord
Joined: Aug 2007
Posts: 14,052
From: Holland
Capicitors are known that they can loose their value of capacity but normally that can take decades.
Another very well known problem are expanded capacitors:
They will swallow up on top or bottom.
But I do not think you will experience this.....
Another very well known problem are expanded capacitors:
They will swallow up on top or bottom.
But I do not think you will experience this.....
08-19-2015 | 11:25 AM
#8
Tech Adept
Joined: Feb 2015
Posts: 106
From: Michigan.
its impossible for a cap to produce dirty power. they are a Strick DC device.. so that manufacturer dont know anything about electronics at all..
a cap is good it equalizes the voltage under load . although it might be for a micro second thats all you need
I always run caps on all my brushless esc.. I build my own cap blocks...
a cap is good it equalizes the voltage under load . although it might be for a micro second thats all you need
I always run caps on all my brushless esc.. I build my own cap blocks...
08-19-2015 | 12:14 PM
#9
A cap stores energy....nothing more than that. None of my Castle ESC's ever had a cap but my recent Trackstar ESC from HK has one. My thinking is its nothing more than a safeguard.
Now, regarding Castle ESC's, I did have to install caps into the receivers because as everyone knows, earlier Castle's BEC's sucked bigtime.
Now, regarding Castle ESC's, I did have to install caps into the receivers because as everyone knows, earlier Castle's BEC's sucked bigtime.
08-19-2015 | 12:48 PM
#11
Tech Addict
Joined: Sep 2013
Posts: 650
From: Germany
The cap is not for the power but to save the ESC.
Several functions are done with the caps:
- filtering out the high frequencies of the swtiching ESC
- filtering out voltage peaks produced by induction on the wires and motor coils.
- take the high current peaks to prevent the voltage drop goes to low and with that keeping the voltage on a better level so the FET's are getting enough to get fully opened.
With no caps it is known the ESC can produce more heat which is not good for its life.
Several functions are done with the caps:
- filtering out the high frequencies of the swtiching ESC
- filtering out voltage peaks produced by induction on the wires and motor coils.
- take the high current peaks to prevent the voltage drop goes to low and with that keeping the voltage on a better level so the FET's are getting enough to get fully opened.
With no caps it is known the ESC can produce more heat which is not good for its life.
Here's another nice explanation, stolen from: http://www.rcgroups.com/forums/showt...php?t=1753720:
Ripple is the difference in voltage the fets see when they turn on - turn off ( load, no load).
Now since some of the components inside the esc need to see certain voltages to operate properly mfg's put capacitors on the incoming line to basically smooth this difference in voltage out. If we didn't things would go boom pretty quick. The biggest thing that will happen if the ripple is to high is the caps will charge & discharge at such a high rate they will eventually be damaged or they simply won't be ably to supply the demand & could cause failure of the esc.
Acceptable ripple is normally 5% of total pack voltage ( 50v - 2.5v Ripple) 10% & things will still work but you can expect a short life from the esc. Over 10 - get better batteries if they are old & weak or add inline caps if the power system is just a monster.
Now since some of the components inside the esc need to see certain voltages to operate properly mfg's put capacitors on the incoming line to basically smooth this difference in voltage out. If we didn't things would go boom pretty quick. The biggest thing that will happen if the ripple is to high is the caps will charge & discharge at such a high rate they will eventually be damaged or they simply won't be ably to supply the demand & could cause failure of the esc.
Acceptable ripple is normally 5% of total pack voltage ( 50v - 2.5v Ripple) 10% & things will still work but you can expect a short life from the esc. Over 10 - get better batteries if they are old & weak or add inline caps if the power system is just a monster.
... Another distorting part are filtering capacitors on the inputs of the controller, which do absorb a part of the energy during braking current pulses.
08-19-2015 | 01:15 PM
#12
You talking an external BEC or just a cap? Regardless, I havent had any issues with them....using Castle Link, you can raise the BEC voltage on the ESC up to around 8.0V (?) and not have any issues with a power sucking servo (read: Savox) This doesnt apply to SW versions tho....
08-19-2015 | 02:45 PM
#13
A cap stores energy....nothing more than that. None of my Castle ESC's ever had a cap but my recent Trackstar ESC from HK has one. My thinking is its nothing more than a safeguard.
Now, regarding Castle ESC's, I did have to install caps into the receivers because as everyone knows, earlier Castle's BEC's sucked bigtime.
Now, regarding Castle ESC's, I did have to install caps into the receivers because as everyone knows, earlier Castle's BEC's sucked bigtime.
Mamba 25
Sidewinder
Mamba Max
Sidewinder V2
Mamba Max Pro
Mamba Monster
Mamba Monster 2
They may not have been obvious because all except that Mamba 25 and Mamba Max had the caps inside the case.
So what Cast ESC have you had that didn't have caps?
08-19-2015 | 05:47 PM
#15
It is quite possible to have an expanded or even exploded cap -- if there is enough amp spike through your system. A bad motor or sensor can do that. The cap can to some extent protect the esc - but its not a guarantee.
Its also possible for a cap to provide a little extra "punch" when discharged, calling it "dirty" or not, any energy stored and then released (even though its a very short time), can be a technical help.
But there are more ways to lose a .1 of a second than there are to gain a .1 of a second.
Its also possible for a cap to provide a little extra "punch" when discharged, calling it "dirty" or not, any energy stored and then released (even though its a very short time), can be a technical help.
But there are more ways to lose a .1 of a second than there are to gain a .1 of a second.