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Feb 25, 2020, 08:32 AM
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Leftyatm's Avatar
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Capacitor install/help


Hey guys.

Running a alien 5 inch. Frame with 2207 2750 motors on the newbee drone and dji air unit. I didnít install a capacitor as it said it wasnít truly necessary but could help. So I am trying it out to sort out a violent tuning issue on landing. Either way, I have a low esr 35v 1000 uf capacitor. Will this work. I plan to mainly run 4s but may use 3s at times.

Attached is.a photo. I assume negative to the side with dash/negative marks. Does it look good to you and is it a suitable capacitor?

Thanks
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Feb 25, 2020, 08:45 AM
Registered User
Not sure what your issue is but that cap will work ok. And yes - the bar is the negative. You might want to explain what you are trying to fix with the cap. IMO the only thing it might do is clean up the video a bit.
Feb 25, 2020, 08:54 AM
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Leftyatm's Avatar
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Quote:
Originally Posted by Volt_Ampere
Not sure what your issue is but that cap will work ok. And yes - the bar is the negative. You might want to explain what you are trying to fix with the cap. IMO the only thing it might do is clean up the video a bit.
Thanks for the response.

So it is running the dji hd air unit. Video is perfect. The quad flies great. When I land, it becomes violent. It spazzes and flips. I have done a lot of research into this and tracked it down to air mode. Well I have tried all sorts of variations with and without air mode. Landing with and without air mode etc.

Well I was speaking with the retailer from Newbeedrone and while they said running 4s a capacitor is not necessary it can help. They seem to think that when my quad touches the ground for a landing, the jolt sends a surge through the controller into the pid loop and that adding a capacitor will in essence dampen any potential surges and this might fix my violent flipping issue when I land.

I have never had a quad do what this thing does on landing. Frankly, it is scary.

I know air mode does funny things but it does it with air mode on or off. And I have seen the airmode bounce and experienced it on my other quads. This thing doesnít bounce, it literally flips out and goes flying around into the ground. It terrifies me. So if adding a capacitor helps, Iím all about trying it. I guess I can see where the capacitor will filter and smooth out spikes being sent through the system? It sounds good in theory.

So it is soldered/wired up properly to be attached to my pdb?
Feb 25, 2020, 09:43 AM
FA3PR9WM79
Oldgazer's Avatar
Quote:
Originally Posted by Leftyatm
They seem to think that when my quad touches the ground for a landing, the jolt sends a surge through the controller into the pid loop and that adding a capacitor will in essence dampen any potential surges and this might fix my violent flipping issue when I land.
This sounds more like "Sheesh, I have no idea what this customer is talking about so since I can't dazzle him with my knowledge I need to baffle him with a load a BS.."

With that being said, unless you have some gawd awful solder connections, or some thing like a chaffed wire touching the frame (which will conduct electricity) when you land, you don't get voltage spikes from a mechanical contact between the frame and terra firma. So, adding the cap MAY have some impact, but you are treating the symptom and not the cause.

I would start by going over the aircraft with a magnifying glass and a strong light, checking EVERY nut, bolt, screw, wire tie, solder connection, cable connection, on EVERYTHING, and I'd do it at least twice to make sure I didn't miss anything.

Give us a complete and detailed list of what components you used (FC, RX, ESCs, etc), as well as which flight controller and radio/receiver firmware you are using.

Also, post pictures of the ENTIRE AIRCRAFT that shows how things are connected and how wires are run. Post a video that shows what happens. If you have them post the Black Box logs.
Feb 25, 2020, 04:22 PM
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dkemxr's Avatar
A power capacitor to dampen surges in the PID loop from landing? Hard to believe a Hobby Shop would give that advise. Well, maybe one named NewBeeDrone... Maybe they are thinking the weight of that 1000uF Cap will dampen vibration

Quote:
Originally Posted by Leftyatm
Thanks for the response.

So it is running the dji hd air unit. Video is perfect. The quad flies great. When I land, it becomes violent. It spazzes and flips. I have done a lot of research into this and tracked it down to air mode. Well I have tried all sorts of variations with and without air mode. Landing with and without air mode etc.

Well I was speaking with the retailer from Newbeedrone and while they said running 4s a capacitor is not necessary it can help. They seem to think that when my quad touches the ground for a landing, the jolt sends a surge through the controller into the pid loop and that adding a capacitor will in essence dampen any potential surges and this might fix my violent flipping issue when I land.

I have never had a quad do what this thing does on landing. Frankly, it is scary.

I know air mode does funny things but it does it with air mode on or off. And I have seen the airmode bounce and experienced it on my other quads. This thing doesn’t bounce, it literally flips out and goes flying around into the ground. It terrifies me. So if adding a capacitor helps, I’m all about trying it. I guess I can see where the capacitor will filter and smooth out spikes being sent through the system? It sounds good in theory.

So it is soldered/wired up properly to be attached to my pdb?
Last edited by dkemxr; Feb 25, 2020 at 09:41 PM.
Feb 25, 2020, 08:43 PM
Registered User
Learn to disarm when landing - best before you actually touch down.
Feb 25, 2020, 11:55 PM
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Leftyatm's Avatar
Thread OP
Quote:
Originally Posted by Volt_Ampere
Learn to disarm when landing - best before you actually touch down.
I do that, I just donít like it. I have several other quads all with air mode and while they may bounce a little, I donít have to disarm and drop it.
Feb 26, 2020, 06:22 AM
FA3PR9WM79
Oldgazer's Avatar
Quote:
Originally Posted by Volt_Ampere
Learn to disarm when landing - best before you actually touch down.
I see no need what so ever to do that. I have aircraft that range from palm sized toys to 700mm+ aerial photography platforms. 2 of those aircraft are racers, and I NEVER disarm and drop. That just a cop out for those who don't know how to hover, and it this case it does nothing to solve the OP's problem.
Feb 26, 2020, 08:46 AM
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Ace12GA's Avatar
Quote:
Originally Posted by Oldgazer
I see no need what so ever to do that. I have aircraft that range from palm sized toys to 700mm+ aerial photography platforms. 2 of those aircraft are racers, and I NEVER disarm and drop. That just a cop out for those who don't know how to hover, and it this case it does nothing to solve the OP's problem.
I don't disarm and drop, but I do disarm pretty much the second I touch down. Ever since I switched over to airmode always on. I used to take off and land with airmode on a switch, turning it off before contacting the ground. Airmode can do some pretty strange things while landing if you do anything but lower the quad slowly with zero lateral velocity. I touch down, and disarm the second I touch down. OP has mentioned this happens airmode, or no airmode, so the disarm on touch down would avoid the issue, but you're right, there is something causing that.

@OP, that cap is to smooth out your video signal, and will do nothing for your stability. As a mechanism to get cleaner video, they work nicely, though more modern equipment doesn't seem to need them any more. As a mechanism to smooth your quad? Nothing. It will do nothing. That capacitor will basically smooth out DC voltage spikes and dips caused by your ESC's during significant throttle input changes. Where this is most commonly seen is on your FPV video link. With significant voltage dips, you can actually get a brown out on your FC, but again, modern FC's don't seem to have these problems like much older designs. The PID loop isn't voltage sensitive, because it is all running in a 5V regulated sandbox, so to speak. It is sitting behind a voltage regulator, and capacitors already. The IMU and processor are actually a little sensitive, so the design of the FC already ensures they get a steady 5V, and no more. Spikes in your main power system will not reach your processor or IMU. If they did, it would kill the FC rather nicely.

Does your FC have black box? If it does, time to record one of these incidents. The FC, specifically the IMU, is getting some noise on landing, which is causing an increasing feedback loop. That happens usually when things are loose. I'd check to make sure the FC is firmly attached to the frame. I'd check the motors for smooth rotation (not counting the notching from the magnets), and movement vertically. I'd check the motor mounts. I'd check the frame arms. Those items can cause all manner of problems. It's also possible you have something in your tune that freaks it out on landing. I'd check the mechanical stuff though. I had a quad with a broken standoff on the FC. Visually, it looked fine, but it caused freakouts under stress; usually hard changes of velocity, or landing.
Feb 26, 2020, 11:56 AM
Registered User
Its always good to have the capacitor. Only down side is if you install it wrong.

Its not just "video signal". That video noise is actually electrical voltage spikes going through and damaging your electronics. Longer cable to battery and higher voltage -> bigger spikes.

A $1 capacitor to protect a $60 ESC... who am I, your dad?

===≠====≠====≠====
Insulate the cap wires. Or better, solder flexible wire. It can easily accidentally touch carbom fiber or aluminum posts and cause "hot flashes".
Feb 26, 2020, 02:04 PM
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Ace12GA's Avatar
Quote:
Originally Posted by romangpro
Its always good to have the capacitor. Only down side is if you install it wrong.

Its not just "video signal". That video noise is actually electrical voltage spikes going through and damaging your electronics. Longer cable to battery and higher voltage -> bigger spikes.

A $1 capacitor to protect a $60 ESC... who am I, your dad?

===≠====≠====≠====
Insulate the cap wires. Or better, solder flexible wire. It can easily accidentally touch carbom fiber or aluminum posts and cause "hot flashes".
With the modern stuff, it's really unlikely you'll cook anything. ESC's are actually your culprits, the ones creating the issue. Some of the early BLHeli ones had major problems with this, and were cooking VTx's. Modern stuff is pretty clean now, unless you really botched your build. Having that capacitor though, totally worth it from a video perspective. Most of my builds have one in parallel to the main battery lead. Honestly, you need to be building with cheap parts, or stuff from 3 ~ 4 years ago, to actually need that cap at this point. Everything is filtered much better than it once was.
Feb 26, 2020, 09:21 PM
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Leftyatm's Avatar
Thread OP
Thanks for your input. I dont believe it has a black box. At oldgazer thanks. I agree all my other builds land with maybe a slight bounce but not what this quad does. It’s unacceptable to me to have to drop it. I like precise landings part of the fun for me.



At ace12g yea I tried disarming immediately upon touching the ground. If I do, it literally will not hop but violently flip and dart toward the ground with full motor input on some of the motors. My other quads, I always disarm when I hit the ground and no issues arise. Maybe a slight bounce, but that’s airmode.


At Romang, yes I agree the capacitor is worth it. I just put it on. A previous build I have had some lines, in the analog fpv feed so I’ll certainly add a capacitor. I did solder wires to the capacitor, I the. Got glued all around where they mount to leads and to the base of the capacitor for better reinforcement as those tiny wire strands do seem like they would bend and fatigue thus break easy. I did all that and wire shrimped it. Almost looks professional. I then soldered them into where my battery leads go to the pdb.

At ace12g I am running newer stuff. It’s the designed newbee drone combo stack with fc and 4in 1 esc with the dji air unit. All pretty much plug and play. The interesting thing is that I run the same exact hardware on my rotor riot hd1 frame and no capacitor and it does not do what this particular build does. That is why I am determined to fix the issue.

I have my flight controller loosely mounted so that it can wiggle a bit on the standoffs and grommets. I though everyone was soft mounting their flight controllers? Maybe mine is too loose. I can try tightening it a bit but then there is no play. I thought you wanted a bit of give. Maybe not?

I understand the calcifies are mainly focused on cleaning video feeds. I do not think it applies to hd video feeds? Maybe it does? Either way, I have been in contact with the vendor at Newbeedrone and they firmly believe the capacitor will dampen any voltage spikes that do travel through the entire system. I don’t know as I am not an electrical engineer. I have been in the hobby for years and am a decent pilot but am by no means an electronics expert. I get by. The build is not shoddy in the least. All solder joints are clean and shiny. I take pride in my soldering abilities. I just don’t know what’s causing it. I do want to try to land it again on the ground without dropping now that the capacitor is installed, but I have alredy gone through several sets of props and ruined two lipos as when it lands and does it’s violent flipping, it is so extreme it has either ejected the packs or smacked the ground so hard, it destroyed the lipos. One got punctured by hitting the pavement and the other it must have broke something internal as a cell drop. So when I say it becomes violent and flips on landing J am not exaggerating. I will attach photos below to show the build and capacitor. See if I am missing anything. Either way thanks genelemen.

Sorry for photos being blurry. My phone is being buggy. As far as the quad, just so I am clear, in the air, it flies smooth and great. It has the same pid tune and betaflight firmware as the other identical set up that flies great. The motors come down cool. The esc and fc are cool. It’s only landing that it bugs out. Thinking back actually. Only once, I was doing aggressive pitch pumps and on one, it flipped and went crazy in the air.

My motors are all the same. Are buttery smooth aside from notchiness from magnet poles. And all motor wires are secured. Nothing loose. No cold solder joints. And it’s a 4 in 1 esc so all esc’s are the same. I wonder if it’s the build or somewhere in the esc/fc stack and if they would exchange it for another one if I would have the same issue??
Last edited by Leftyatm; Feb 26, 2020 at 09:35 PM.
Feb 26, 2020, 09:25 PM
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Leftyatm's Avatar
Thread OP
Pocs.

The only difference in the quad with ifentival hardware is I only ran 4s. With this new build, maiden into it. I only tried 3s as they were my cheaper batteries. Since it has proven to be untrustworthy, I have been afraid to strap on my good 4cell packs. Do you think that could be an issue too?
Feb 26, 2020, 09:45 PM
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Leftyatm's Avatar
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This is the combo I am using.

https://newbeedrone.com/collections/...0-stack-bundle


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