The truth about Capacitors!

[BART]

I'll try to make this as simple and as useful as i can.

I have read plenty of misconception on this site about the use of capacitors for performance gains. First of all, replacing or adding capacitors to your motor will not make your car faster, in fact it will make it slower. A capacitor is an electrical storage device which discharges it's stored energy very quickly when presented with a load in which to discharge. If placed on the motor leads or directly on the motor itself it would have to use the energy which was intended to power your motor to charge the capacitor (which would take away from the energy that was intended for your motor in the first place).

The capacitors that are already on your motor are intended to reduce "noise" produced by a brushed motor and to absorb peak transient voltages caused by counter emf which occurs at high speeds and when the power to the motor is suddenly cut off.

Now for the slightly good part, there is a way to use capacitors for a slight performance advantage.

If a capacitor is connected to the battery connection of the main board (and in this case bigger is better) the capacitor would be charged whenever the batteries are inserted and able to discharge on demand much quicker than the batteries themselves whenever the board demanded power (when you hit the gas). The gains would be small but from reading your posts most of you guys are looking for any advantage possible.

A capacitor could be connected anywhere along the wires from the battery tray to the board but the closer to the board the better.

[Numbchux]

nice...but I've got a better place for this :nod:

[streetballerzz3]

great job zx9rbart explains it in good detail

[Red10152]

so if i took the capacitor (the little Orange thing with a number on it) off my motor would it go faster or just be really noisy

also i can put a capacitor on the battery wires to th eboard and it would be a slight performance boost

[BART]

so if i took the capacitor (the little Orange thing with a number on it) off my motor would it go faster or just be really noisy

also i can put a capacitor on the battery wires to th eboard and it would be a slight performance boost

1...no dont do it, I'm not talking about noise you can hear. 2...yes,read my original post in its entirety.

[texan_idiot25]

Truth about capacitor turbos on the motor? Indeed, read the thread

http://xmodworld.com/modules.php?name=Forums&file=viewtopic&t=20824

[BART]

Truth about capacitor turbos on the motor? Indeed, read the thread

http://xmodworld.com/modules.php?name=Forums&file=viewtopic&t=20824

Thanks...I think that backs my claims up pretty well.

[RedSXmodder]

I did some searches on your capacitor trick, and I learned alot. But I have a few questions.

1) If the capacitor is farther away from the board, what are the negative effects? I don't think it'd be too noticeable, unless you really know the powers of the capacitor your using, right?

2) The capacitor fills, and discharges, many times a second, is there a way that could cause jumpiness in response (lowering smoothness and control ever so slightly) or becuase its connected to the battery it would have nothing to do with it?

3) Say I wan't my xmod as smooth as a mini-Z, would putting capacitors on the battery, servo, and motor create excellent, smooth response?

4) Does the size of the capacitor create different filtering effects? I know that the bigger the one on the battery section would be better, but if you had a smaller one on the motor and servo would it still be able to filter as well or better then a bigger one, or is the bigger one better?

I know putting a capacitor on the servo wouldn't do much, since its only being used when that particular function has battery power going through it (along with the motor) but it still should filter electrical noise on the servo motor. Also, would you be able to put a capacitor near the board by the servo and use that as a torque effect, and then have a capacitor up on the motor acting as a filtering effect.

I guess I'm kinda asking the same question over and over again, but, I'm learing alot about this whole thing...

Later,
RedSXmodder

[BART]

I did some searches on your capacitor trick, and I learned alot. But I have a few questions.

1) If the capacitor is farther away from the board, what are the negative effects? I don't think it'd be too noticeable, unless you really know the powers of the capacitor your using, right?

The closer to the source the better but you would likely never see a noticeable difference in this situation

2) The capacitor fills, and discharges, many times a second, is there a way that could cause jumpiness in response (lowering smoothness and control ever so slightly) or becuase its connected to the battery it would have nothing to do with it?

No...it does not fill and discharge many times a second. It fills when supplied with power and discharges when presented with a load (just like a rechargeable battery only much faster)
3) Say I wan't my xmod as smooth as a mini-Z, would putting capacitors on the battery, servo, and motor create excellent, smooth response?

4) Does the size of the capacitor create different filtering effects? I know that the bigger the one on the battery section would be better, but if you had a smaller one on the motor and servo would it still be able to filter as well or better then a bigger one, or is the bigger one better?

I think the problem you are getting to here is not the smoothness of the servo but glitches in the radio system


I know putting a capacitor on the servo wouldn't do much, since its only being used when that particular function has battery power going through it (along with the motor) but it still should filter electrical noise on the servo motor. Also, would you be able to put a capacitor near the board by the servo and use that as a torque effect, and then have a capacitor up on the motor acting as a filtering effect.

You couldnt use a cap for added torque on a servo as it would only charge when powered (you kinda answered this for yourself above)

I guess I'm kinda asking the same question over and over again, but, I'm learing alot about this whole thing...

Later,
RedSXmodder

I answered below each question...not quite sure how to do all the fancy quote in blocks stuff.

[RedSXmodder]

Realisticly, the only real advantage of a "turbo cap" would be at the board connection to the batteries.

Also, having a bigger cap on the servo and motor would help smooth out electrical noise, and cause smoother throttle response, and servo response, right? (I still don't understand your answer to that one) Or would it just filter noise, and leave it at that?

Thanks for the other answers though!

Later,
RedSXmodder

[BART]

Realisticly, the only real advantage of a "turbo cap" would be at the board connection to the batteries.

Also, having a bigger cap on the servo and motor would help smooth out electrical noise, and cause smoother throttle response, and servo response, right? (I still don't understand your answer to that one) Or would it just filter noise, and leave it at that?

Thanks for the other answers though!

Later,
RedSXmodder

A cap on the servo would be useless...it would slow steering response and i dont think the jitter in xmod servos is from noise. A bigger cap on the motor would smooth throttle response but i see it as useless. More could be done with smoother finger control and besides that when you nailed the throttle you would actually lose some acceleration as the cap would have to be charged from the same power source you are trying to feed the motor with. And yes...the only advantage would come from putting a cap on the board at the battery connections (I have done this and posted about it...look up experimenting)

[RedSXmodder]

Yep, I gotcha now.

The only usefull place for a capacitor is the batter connection to the board. I'll have to expiriment with this like you did...

I want an xmod that can rival a Mini-Z's responce and smoothness...

Later,
RedSXmodder

[Stampedekid]

what about capacitors on motors?

[RedSXmodder]

Read the **** thread!

[Stampedekid]

sorry, i have to sign off soon thats why, i wanted a quick explanation

[BART]

sorry, i have to sign off soon thats why, i wanted a quick explanation
One filters the electrical noise caused by the brushes opening and closing as they cross from the north to south poles on the armature. The other smooths out the square wave which is output by the fets. They are fine...leave them alone.