RC-Monster Forums - ESC Capacitors

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I just picked up some 35v 330 UF caps for my MM, and i forgot which way there soldered on... Anyone care to share how they went again?
would appreciate it.

Caps are marked with a "-" which is connected to the neg main power input.

Use a meter to see which side is -ve check for continuity between the negative side of the power and the solder points.

And they should be soldered as close to the ESC as possible for max benefit. Here is a thread that shows how I did my Quark. I know it's a different ESC, but the principles are the same: http://www.rc-monster.com/forum/show...91&postcount=2

Quote:

Originally Posted by mwry13 (Post 127155)

I just picked up some 35v 330 UF caps for my MM, and i forgot which way there soldered on... Anyone care to share how they went again?
would appreciate it.

http://forum.rcdesign.ru/index.php?a...ntry&id=110934

Whats the difference between caps with say a 330 Uf and the same voltage caps with like 1800 Uf... Is it better to be closer to whats stock on the MM? or should i go all out and get a big cap with a high Uf number?

uf is the capacity of the capacitor. Bigger the number the more energy they can store. Having one 2000uf cap is the same as having 20, 100uf caps. However, I believe having less caps is more efficient.

Quote:

Originally Posted by BP-Revo (Post 127564)

So would you say having 2 or 3 330 Uf caps is better than having 1 1800 Uf Cap or something in that range?

i would say the more the better because the more surface area will help with cooling. but on the otherhand u have slightly higher resistance

Quote:

Originally Posted by jokerjustin (Post 127568)

i would say the more the better because the more surface area will help with cooling. but on the otherhand u have slightly higher resistance

Surface area of what??

Quote:

Originally Posted by mwry13 (Post 127567)

So would you say having 2 or 3 330 Uf caps is better than having 1 1800 Uf Cap or something in that range?

Thats the opposite of what he said...

2x330=660
3x330=990

or just 1800Uf and you surpass have 2 or three, and with what he said about having less is more efficient, having 1 1800Uf is obviously more efficient and better. At least thats what I got from what he said...

i ment more cap surface area for better cooling

Quote:

Originally Posted by squeeforever (Post 127576)

Surface area of what??

I assume he means the total capacitor surface area is larger, which reduces heat.

However, I personally have never had a capacitor heat up anything over room temperature. I used 3 25v, 2700uf capacitors wired in series with my HV4.5 and they added a significant amount of punch, as well as lowering my ESC temps a good 10* F.

Thats what I thought he meant, but it didn't make any sense since they shouldn't heat up...

Ahhh thanks for the help guys... appreciate it... now if i can find my camera when i hit up the track on friday... ill post a small vid :yipi:

Having more of a smaller uF cap will have the least resistance, much lower than one large cap.

Quote:

Originally Posted by zeropointbug (Post 127639)

Having more of a smaller uF cap will have the least resistance, much lower than one large cap.

I wonder if the resistance is measurable with a simple ohm meter?

Hi Zeropointbug. Did you get your Quark ESC fixed?

You can't measure ESR with an ohmmeter. A meter outputs a small voltage and either measures current flow or measures the v drop on an internal resistor, and then calculates the resistance. If you put a meter on it, you'll see the resistance start very low and then rise until infinity.

This resistance, which should be called ESR for this discussion, can not be confused with Xc, which is capacitive reactance. Xc is a "resistance" as well, but the current is 90* out of phase with the voltage and the Xc "resistance" value changes with frequency (hence "reactance"). ESR is not Xc, but sorta like the 0* phase DC resistance.

Quote:

ESR Defined
ESR is the sum of in-phase AC resistance. It includes resistance of the dielectric, plate material, electrolytic solution, and terminal leads at a particular frequency. ESR acts like a resistor in series with a capacitor (thus the name Equivalent Series Resistance). This resistor can cause circuits to fail that look just fine on paper and is often the failure mode of capacitors.

To charge the dielectric material current needs to flow down the leads, through the lead plate junction, through the plates themselves - and even through the dielectric material. The dielectric losses can be thought of as friction of aligning dipoles and thus appear as an increase (or a reduction of the rate of decrease -- this increase is what makes the resistance vs freq line to go flat.) of measured ESR as frequency increases.

As the dielectric thickness increases so does the ESR. As the plate area increases, the ESR will go down if the plate thickness remains the same.

To test a Capacitors ESR requires something other than a standard capacitor meter. While a capacitor value meter is a handy device, it will not detect capacitor failure modes that raise the ESR. As the years go by, more and more designs rely on low ESR capacitors to function properly. ESR failed caps can present circuit symptoms that are difficult to diagnose.

This meter is something one can use to measure ESR: http://secure.transtronics.com/CAP-WIZARD.htm

Quote:

Originally Posted by BrianG (Post 127664)

Precisely! :wink:

sikeston34m.... nomods sent me a burnt out Quark with what a appears to be a good brains board on it, but unfortunately, i popped it onto my Quark, but no luck, doesn't even turn on. I noticed it has two little tiny caps missing from the board near the motor phase sensor end (where you solder it).

If anyone has a Quark they are willing to part with (that has overheated, or w/e) and knows the brain board is fine.... I am accepting them! :whistle::wink:

Excellant Information Brian! Thank you. I have attempted to measure them before and noticed how they charge up under the meter.

I was hoping to catch you Zeropointbug. I need a favor from you.

I am doing some research on the Quark line and what I need to know is this. I need to study the Gate Lead Driver circuits on the brain board of the Quark to figure it's amp carrying capacity. I do have an 80 amp Quark here, but this requires disassembly, and separation of the two boards to get the numbers from the driver fets. I'm not willing to take mine all apart, I'm using it.

I looked at your pictures and they are not close up enough to get the numbers. Do you have any extreme closeups of the Quark Brain?

Take a look at my thread on "Quark ESC Power Board Mods/Comparisons" to see why I need this. There may be some things there that interest you.

Yeah, I just got my internet connection back from it being down for a week! :no:

Do you need the reverse AND top pics of the brain board? I do have pics of them close up, but I am not sure if you can see any numbers... I will get some pics for you as soon as possible! Anything else? :smile:

I really need both sides of the brain board. Extreme closeups that will show the numbers on the components.

Some of the numbers are almost too small for me to see with my naked eye, but the camera has a way of really blowing it up.

Welcome back ZPB. I thought you were probably vacationing.

Okay, check out my pictures in my sig..... there will be 3 pics of the brain board at the end. :yes:

Great!

On the last picture, the 3 fets in a row are the gate driver fets. The top number looks like I1760. Is this correct?

The top number is the model number and the only one I need. The others are date codes and such.