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Littlebee 20A ESC burns VTX?
#1
I have been hearing of issues with LittleBees burning up cameras and VTx because of active braking sending surges up the power lines. I am recommended putting a 1000uf 16v capacitor across the main power input where your vTX connects as this keeps those surges from killing your components.

I'm curious how will a capacitor at the main power input control voltage if the surging is happens within the PDB? Does the cap absorb the surges and helps regulate the entire PDB? I’m not sure how that works?
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  • Oscar
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#2
My guess here.
The ESCs are usually fed from the battery directly and therefore the surges may occur in the main power line, affecting everything connected in parallel (PDB, separate BEC, vTx fed directly from the battery).
The capacitor between the battery and consumers or between the battery and all the ESCs achieves necessary filtering of said surges.
Since you feed the ESCs from the battery and not the PDB, there should be no surges on PDB's output.
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#3
what capacitor would you use ?
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#4
As capacious as possible for desired size, as the cut-off frequency is proportional to 1/C, and we want reaction to spikes as little as possible. But that's from the point of view of control theory, I'm sure there are some electronic nuances.
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#5
Im using Littlebee and happened to me twice actually, burned my two newly installed pilot cam Sad .  As what I checked on MRM website regarding the Zeus/LittleBee esc "Voltage Spikes" thing. What I did was, I just replaced my pdb to ATAS PDB Pro cos it comes with 5v/12v output which i found it very safe. Plus integrated LC Filter which is very useful and very clean for the FPV video feed.

Now all ok and working well.

You can check the IMPORTANT note below;
http://www.multirotormania.com/30-amp/12...p-esc.html
•••Repair...Fly...Race...AP...Repeat•••

https://www.facebook.com/yangcheng06FPV/

YouTube Channel: https://www.youtube.com/user/yangcheng06/featured
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#6
Many thanks guys.

My friend got the same setup and burned his fpv cam now I can direct him to check out here.
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#7
For 4s setups a 16v 1000uf cap should be enough. They are relatively small too.
Fly it like you stole it!
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#8
(13-Jan-2016, 06:08 PM)David Trounstine Wrote: For 4s setups a 16v 1000uf cap should be enough. They are relatively small too.

I would use a 25v just be safe, you can get some spikes that could be too much for the 16v right at the battery.
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#9
(13-Jan-2016, 11:25 AM)YangCheng06 Wrote: What I did was, I just replaced my pdb to ATAS PDB Pro cos it comes with 5v/12v output which i found it very safe. Plus integrated LC Filter which is very useful and very clean for the FPV video feed.

Great PDB recommendation! I'll have to order one for my next build.
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#10
I just ordered a bunch of 1000uF 16v capacitors. I'm hoping to use them on my quads. I think it's better to use 32v caps. I'm just wondering what would happen if there's too much voltage for the 16v cap?
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#11
I normally put 4x470uf 25V caps on my setups. one on each ESC. Remember to get low ESR capacitors
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#12
On 4S I would put a 25v capacitor just to be safe. The LB20A do cause spikes that sometimes go to the upper 20v - which is what burns the voltage regulators on VTX, most are not rated higher than 20v. A 440uF should be enough, if 1000uf starts getting bigger. Electrolyte capacitors have polarity - usually one leg is marked as (-), make sure it connects to the negative or ground battery pin. Otherwise there will be a loud bang shortly after you plug in your LiPo Smile I changed a pair of undies when it happened to me the first time.

How it works - generally like a small but fast-reacting buffer. The smaller the capacitor, the quicker it reacts but also with smaller force (smaller buffer):

1. For voltage drops - it compensates for the dip with the energy stored inside.
2. For spikes - the theory at-least the way I've read it is that, the capacitor is never really full. Meaning there is always more room to absorb electrical energy if the voltage is increased. So the spike naturally makes the capacitor absorb it. Because it reacts quickly - the voltage regulator or other sensitive electronics are not affected by the worst part of the spike. In most cases, the capacitor just needs to take the tip of the spike off - or smooth it out a bit.
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#13
Hi everyone. High Five
simple question I hope.
I have some FVT Littlebee 20A Pro ESC OPTO arriving in the mail soon.  I stumbled accross this thread and now Im wondering if I need to do anything to deal with voltage spikes.
I am using this PDB.
https://www.amazon.com/gp/product/B017IH...UTF8&psc=1
It states that it has LC Filter to provide smooth DC voltage to FPV camera.
Will this PDB work as is or do I need to add capacitors to it as well. Do you think the built in LC filter is strong enough or quality?Huh  
If I do need to add caps, where do you suggest I place them?
Sorry if this is a beginner question, I just don't want to fry anything.
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#14
Adding a cap on the main battery lead won't hurt.
Just add a 470uF or higher low-ESR cap rated for 35V. Solder it in parallel to your main battery lead, while ensuring correct polarity.
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#15
I always put capacitors on my escs and the rule of thumb is that they should be placed as close to the source of noise as possible. On your setup, I would probably just solder one cap on each of the ESC power pads on the PDB. I normally use 4x470uf 25V low esr capacitors: http://www.ebay.com/itm/10-X-Rubycon-25V...8Gm-hcGmYA
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