Capacitors For Noise Filtering in Mini Quad

Capacitors can make your FPV video cleaner, and your mini quad fly better. But what capacitor should you get? In this article we will discuss the type of low ESR capacitors for your quadcopter.

Why Low ESR Capacitors are Important to Mini Quad?

By adding low ESR capacitors to your mini quad’s power you get the benefits of:

  • Reduce video noise
  • Reduce noise that could corrupt motor/ESC/radio signals
  • Clean up electrical noise in power system could improve your quad’s flying performance, by lowering noise getting to Gyro sensor in the flight controller
  • It might even save your electronics from damage by active braking voltage spikes

The noise issue has become much more serious since we have more powerful mini quad motors and ESC, by adding capacitors it help clean up our power a great deal.

We prefer low ESR capacitors for our purposes. ESR stands for “Equivalent Series Resistance“. Basically capacitors with lower ESR show better filtering capability as demonstrated in this video.

LC filters are often used to combat video noise, but it only protects the FPV system after the noise is induced. Capacitor on the main power protects the entire system by preventing the noise from being induced in the first place.

Do I need capacitors in my mini quad build?

You don’t have to use caps, but we recommend it.

If you have a noisy quad (lots of oscillations and hard to tune PID), or noisy video feed, adding capacitors would probably be the first thing to try.

Even if you don’t have a noisy build, it’s still good practice to do so. Better safe than sorry right? :) Also bent or broken props could introduce noise in your power, the added caps might actually help with that too.

Where to Install Capacitors in a Mini Quad?

First of all, it’s extremely important to understand the polarity of a capacitor, which leg is positive (+) and which is negative (-). If you make a mistake,  the capacitor won’t work or even explode! The shorter leg indicates negative, as well as the negative strip labelling on the body.

There are normally 3 places you would place your capacitors (only need to place caps in one of these places).

1. On the PDB, where XT60 pig tail is soldered to.

2. On the PDB, where ESC power leads are soldered to.

3. Or on the ESC power terminals (the best locations IMO)

The best place to solder your capacitors would be on the ESC power terminal pads (3rd way). The closer your capacitor is to the source of the noise, the more effective they are. However you’ll need to solder a capacitors for each ESC, small ones would do fine such as 330uF (4 caps in total).

But if size is a problem you can alternatively solder 1 or 2 big ones on the PDB (e.g. 1x1000uF or multiple 470uF), but it might be less effective as the caps are further away from the noise sources. However I use this way on a couple of quads and they both work great.

Make sure to cut the legs as short as possible so you get minimum ESR, these leads don’t conduct high current very well. If you want longer length, you could use thicker wires (e.g. 20awg) to connect the roots of these leads, and it actually doesn’t seem to increase ESR.

Low ESR Capacitor Choices

Here’s a great list of low ESR capacitors from a google spreadsheet, as well as their size and weight so you can pick one that suits your need.

Capacitors rated for 25V should be enough for most cases, but if you want extra safety you can consider 35V, because voltage spikes might sometimes reach higher than 25V.

For example this one looks fine from product description: http://amzn.to/2rvJL1a

Let me know where you get your capacitors from and I will try to add them to this article.

330uF – For Individual ESC

25V

Brand Series Size (D X L) Impendance (Ω/100 kHz)
Panasonic FM 10×12.5 0.038
Elna RJF 10×12.5 0.039
Vishay 160 RLA 12.5×25 0.04
Panasonic FM 8×15 0.041
Samwha ML 10×12.5 0.053
Nippon KZE 10×12.5 0.053
Panasonic FR 8×11.5 0.056
United Chemi-Con (UCC) KZH 8×11.5 0.062
Nippon KZH 8×11.5 0.062
Samwha MZ 10×12.5 0.08
Panasonic FC 8×15 0.085
Panasonic FC 10×12.5 0.09
Nichicon PW 10×12.5 0.09
Samwha MK 10×12.5 0.098
Panasonic TP 10×16 0.13
Elna RJ4 10×12.5 0.81

35V

Brand Series Size (D X L) Impendance (Ω/100 kHz)
Panasonic FM 10×16 0.026
Elna RJF 10×16 0.028
Panasonic FM 8×20 0.03
Samwha MZ 10×16 0.038
Nippon KZE 10×16 0.038
Vishay 160 RLA 12.5×25 0.04
Panasonic FR 10×12.5 0.043
United Chemi-Con (UCC) KZH 10×12.5 0.045
Nippon KZH 10×12.5 0.045
Panasonic TP 10×20 0.052
Samwha ML 10×12.5 0.053
Panasonic FC 8×20 0.065
Samwha MK 10×16 0.065
Panasonic FC 10×16 0.068
Nichicon PW 10×16 0.068
Elna RJ4 10×12.5 0.7

470uF – For ESC’s or PDB

25V

Brand Series Size (D X L) Impendance (Ω/100 kHz)
Panasonic FM 10×16 0.026
Elna RJF 10×16 0.028
Vishay 160 RLA 16×25 0.029
Panasonic FR 8×20 0.03
Samwha MZ 10×16 0.038
Panasonic FR 8×15 0.041
Nippon KZE 8×20 0.041
Panasonic FR 10×12.5 0.043
United Chemi-Con (UCC) KZH 10×12.5 0.045
Nippon KZH 10×12.5 0.045
Samwha ML 10×12.5 0.055
Samwha MK 10×20 0.06
Samwha MK 10×16 0.065
Panasonic TP 8×20 0.067
Panasonic FC 10×16 0.068
Nichicon PW 10×16 0.068
Panasonic TP 10×17 0.13
Elna RJ4 10×12.5 0.57

35V

Brand Series Size (D X L) Impendance (Ω/100 kHz)
Panasonic FM 10×20 0.019
Elna RJF 10×20 0.02
Nippon KZE 10×20 0.023
Samwha MZ 10×20 0.027
Panasonic FR 10×20 0.028
Panasonic FR 10×16 0.028
Panasonic FR 8×20 0.03
Nichicon UHW 10×16 0.03
Nippon KZH 10×16 0.032
United Chemi-Con (UCC) KZH 10×16 0.032
Vishay 160 RLA 18×20 0.035
Panasonic TP 12.5×20 0.038
Samwha ML 8×20 0.038
Samwha ML 10×16 0.041
Samwha MK 10×20 0.05
Panasonic FC 10×20 0.052
Nichicon PW 10×20 0.052
Samwha MK 8×20 0.088
Elna RJ4 10×16 0.5

1000uF – For PDB Main Power

25V

Brand Series Size (D X L) Impendance (Ω/100 kHz)
Elna RJF 12.5×20 0.017
Panasonic FR 10×25 0.018
United Chemi-Con (UCC) KZH 10×25 0.018
Nippon KZH 10×25 0.018
Panasonic FR 10×20 0.02
Nichicon UHW 10×20 0.02
Nippon KZE 12.5×20 0.021
Samwha MZ 12.5×21 0.025
Vishay 160 RLA 16×31 0.027
Samwha ML 10×20 0.033
Vishay 136 RVI 12.5×25 0.034
Panasonic FC 10×30 0.035
Panasonic FC 12.5×20 0.038
Nichicon PW 12.5×20 0.038
Panasonic FC 16×15 0.043
Samwha MK 10×25 0.045
Samwha MK 10×20 0.05
Elna RJ4 10×20 0.27

35V

Brand Series Size (D X L) Impendance (Ω/100 kHz)
Panasonic FM 12×25 0.015
Elna RJF 12.5×25 0.015
Nichicon UHW 12.5×20 0.017
United Chemi-Con (UCC) KZH 12.5×20 0.017
Nippon KZH 12.5×20 0.017
Panasonic FM 12.5×20 0.018
Nippon KZE 12.5×25 0.018
Samwha MZ 12.5×25 0.022
Vishay 160 RLA 18×35 0.024
Samwha ML 12.5×20 0.026
Panasonic FC 16×20 0.029
Samwha MK 12.5×25 0.029
Panasonic FC 12.5×25 0.03
Nichicon PW 12.5×25 0.03
Samwha MK 12.5×20 0.043
Elna RJ4 12.5×20 0.23
  • Panasonic EB, EE, HD, NHG,GA, M, SU, KA and KS series are not low ESR
  • Samwha SD, BH and RD series are not low ESR, WL and WF are mediocre
  • United Chemi-Con (UCC) with KZM series is comparable to KZH
  • There are much more low ESR Vishay capacitors, but they are just too big
  • Rubycon low ESR capacitors go only up to 220uF – thus not show here
  • Elna RJ3 and RJ4 are comparable

18 thoughts on “Capacitors For Noise Filtering in Mini Quad

  1. Ben T

    Hi Oscar,

    Thanks for doing all these videos and sharing the knowledge.

    I put 4 330f Panasonic FM capacitors on my 5″ quad. Emax 2205S, 2300 kv with Aikon 20A ESCs.

    When I plug in, motor 4 will start to spin on its own, even with the quad unarmed. Do I need to re-set the end points or do some sort of recalibration somewhere?

    Ben

    Reply
  2. Cyril MARTINEZ

    Very nice article and explaination.
    As i am willing to build micro quad, i was wondering if the use of capacitors is necessary, du to the increasing weight, and the lack of space inside those frame ?
    What about using capacitors when using 2 in 1 or 4 in 1 ESC’s ?

    Reply
    1. Oscar Post author

      for a micro quad? I don’t think it’s necessary. But it wouldn’t hurt to add one in if there is space.

      Reply
  3. Shamsher

    Will adding the 4 smaller caps to esc’s also clean up the power going to the 5v and 12v bec, or should I use one 1000 micro farad cap on the battery lead? Also will the 4 smaller 25v caps add up their voltage incase the spike is greater than 25v? ( E.g. for a combined 100v protection with the 4 caps)

    Reply
  4. NickB

    Hello Oscar. What about dshot and adding extra capasitors? Are they also needed? I assume that you also have spikes, but people are removing caps from their escs? Or this is irrelevant.

    Reply
    1. Oscar Post author

      People are removing caps to run DShot because it was connected to the signal.
      The Caps we are adding here are connected to the power, so different caps.

      Reply
  5. Scott Cline

    Thanks for this article Oscar. It helps explain a lot of things about adding a capacitor to your build that I would have spent days/weeks/months trying to figure out.

    Reply
  6. Ronald Kotila

    Help I have capacitor Says CKHM 1000uf 25v B105degrees c with number 17 on it and ic circled r will these work on my Quads

    Reply
  7. Ruben

    I read a lot if the size of the caps. Some say 1 470 uf on pdb is enough, other say 1000uf is needed. Does it matter how much caps on the esc itself is placed? Like a total uf on the whole quad?

    Reply
    1. Oscar Post author

      there is no rules on total uf required, it depends on how noisy your quad is.
      But generally speaking 330uF on each ESC, or 1000uF on PDB works for most people. 470uf on ESC would even be better, but a little bigger.

      Reply
  8. Ben

    Gee it would be nice if there were non cylinder shaped Capacitors. Maybe rectangular/cube or circuit board style that could be mounted in line with an esc on the arm of quad.

    Reply
    1. Oscar Post author

      LC filter reduce noise getting into your FPV setup… capacitors “clean” noise in your power, so yes, it’s okay.

      Reply
  9. 1337Flite

    No “might” about caps saving your electronics.
    I lost at least 2 x FCs, 1 VTX and an RX for no apparent reason before I found out about spikes, ESC braking and capacitors.
    I now run a single 220uF 25v cap on each ESC and my video is better, but more importantly I have not lost a single component since (except the Tramp I bent in half in a crash – not spike related).

    Reply
  10. Dean Buckner

    What size caps would you recomend when using 2 6s lipos to feed a heavy life six rotor? Not sure what the escs are,,,I would say 40amps

    Reply

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