Would like to put the cap here directly. Due to space the only other option would be to run wires under the ESC and solder the cap to the wires but I’d rather not.

Nope. You can solder it directly to power wires only.

(26-Sep-2023, 10:42 PM)lyoha Wrote: Nope. You can solder it directly to power wires only.

Even if those pads are on the VCC trace? There's dedicated cap pads on the other side that aren't "directly" attached to the power wires.

Edit: Found THIS thread just now. Looks like it's fine. ESC arrives tomorrow so I'll see if anyone else chimes in. Thanks.

You want it to be as close as possible to your main power pads.

Yes, you can use vcc & ground, but personally I would probably choose to instead clip the leads on the capacitor and solder on short jumper wires long enough to reach where it needs to be mounted.

If’n your extension wires would end up being longer than the trace to that vcc pad, then, go for it.

Edit- I would definitely use the vcc/ground pad on the esc board rather than the fc board- no need to have it running through two connectors and a wiring harness.

(27-Sep-2023, 01:02 AM)Lemonyleprosy Wrote: 1) You want it to be as close as possible to your main power pads.


2)If’n your extension wires would end up being longer than the trace to that vcc pad, then, go for it.

1) Yea that's how I've always done it but that was in a 1/7 speed run car with a ton of space and pulling over 600amps.

2)That's exactly what would happen so I'll just use the VCC pad.

Thanks!

I'll third the "no" even though it seems you don't care. The cap should be soldered directly to the ESC power pads, either with very short leads or using some heavier gauge wire as an extension. The resistance of the trace running to the VCC pad will make any cap mounted there useless.

(27-Sep-2023, 02:20 AM)V-22 Wrote: I'll third the "no" even though it seems you don't care. The cap should be soldered directly to the ESC power pads, either with very short leads or using some heavier gauge wire as an extension. The resistance of the trace running to the VCC pad will make any cap mounted there useless.

I do care hence the reason I was asking. When I ask questions I like to understand the why also, and that's where forums come into play. The only reason I even thought about mounting it there is because fettec has pads in almost the same spot on the 45amp ESC so it got me thinking about other options for mounting. If it's useless to have a cap there then I'm genuinely curious as to why they put them there.

Hi LicketySplit,

Hmmm.

First, the cap will work soldered to the pins that you have listed. It may or
may not be as effective, however, that is debatable. Well, the traces might 
be heavier for that than one might think. Unless one specifically knows 
the physical technical details, then who can say. 

Next, there is controversy over the use of "extension" wires on the cap;
some say it is ok while other say it isn't. I have used extension wires
up to about 50mm and the cap seems to work just fine. 

Let's consider what a capacitor does and why we would use one. A
capacitor is an energy storage device and is basically used to stabilize
the voltage on the circuit; IE: reduce spikes that effect the video image
(at least in an analog system; I don't know about digital gear). Since
a battery will not generate more voltage than it has to start with, where
do spikes come from. They come from the motors when the throttle is
suddenly moved from full throttle to zero. The props continue to spin the
motors which now act as little generators with no voltage regulation on
them, hence the voltage can exceed that of the battery (a spike) which
the capacitor absorbs (assuming that the voltage of the cap is higher
than that of the battery). In fact, the cap absorbs and discharges much
faster than the battery. Also, during a hard throttle punch that drains
down the battery, the cap shunts power into the circuit. The overall 
effect of all of this is that the voltage on the circuit is somewhat
stabilized and voltage spikes are reduced.

From my perspective, the only way to actually see the effect is to try
it. It could be that the traces on the ESC board (you appear to using
a 20x20 stack) are actually heavy enough to work just fine. Only through 
testing will you know for sure. 

Another thing that is often not mentioned is that you can use more than
one capacitor. In the old days where an individual ESC was mounted to
each arm, a cap would be connected right there to each of the ESCs and
sometimes one at the power leads as well. Well, all of the integration has
sort of changed where you can connect a capacitor. On an AIO board, the
power leads are sometimes the only place to connect a cap. 

The only real way to know is through testing and logging the information
with the cap mounted in all 4 configurations:
1) Without a cap.
2) Cap at the location shown (VCC, GND)
3) Cap on battery leads with extensions.
4) Cap in both locations. 

Yeah, that might be a lot of work. So, you might consider mounting the
cap where you have shown. If all goes well during test flights, then leave
it. If you believe that you need more, leave that cap and install a second
one at the power leads using extension wires. Do more test flights. If all
goes well, leave it. 

Personally, I tend to use a larger cap than most people for any given 
application. The cap always seems to work regardless of my mounting and 
I have never had any issues. Yeah, I am running all analog and can tell the
difference between cap and no cap. Ok, to be fair, I don't do hard throttle
punches and don't fly ACRO. My throttle is rarely even up to 50 percent 
for my easy cruising style of flying so my systems are less prone to spikes.

Even thought there are a lot of intelligent members here, SnowLeopardFPV 
is one of the best when it comes to quadcopters in my opinion. He has
helped me a lot and is always spot on. I always trust his answers.

Later, iFly  

iFLY,

Thanks for the response. I also tend to run a larger cap if it's possible. And FWIW, it's a 30x30 stack and the ESC is pretty heavy compared to my other ones. For speed run cars I used to run massive cap packs before Castle released the XLX2. Now people are sending 1/7, 20+ pound cars at over 200mph and packs aren't needed, believe it or not. When I pulled over 600amps the logs said ripple was around a volt and that was on 8s. Is there a way to see ripple in BF logs? Thanks again!

Hi LicketySplit,

Very interesting. I am guessing (yeah, I don't know for sure) that the internal traces on a 
30x30 board are substantial enough to handle the capacitor. Yeah, I am not even sure
that you actually need a capacitor depending on the situation, the build, the video, etc.
In my case, a capacitor is only used to help clear up the analog video, period. 

I don't know much (understatement) about BF logs as I have never bothered with them.
First, most of my FCs don't have BlackBox memory (where the log info is stored). Plus,
I don't recall having an issue where I really needed it anyway. If your FC has BlackBox
memory you will be able to configure it and then download the files. There are some
pretty decent YT videos. 

That is interesting about your RC cars; NICE 

You know, capacitors are basically a type of energy storage device with high charge and 
discharge capacities. They can also be used as a battery replacement in some instances 
because they function just as a battery does. They store energy and provide voltage 
potential difference. 

Keep putting posts in here as you progress with this. I am interested to see how it
works out. 

Later, iFly