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VESC noob: what's the (edit) capacitor for?


#1

Hi guys,
VESC noob here.
What is the CAPACITOR on the input wires for ? Does it come with the VESC or will I need to choose one according to my setup ? How do I choose the size of the condensator ?

Thanks,
Tom


#2

Do you mean the Capacitor?

The VESC i make has the capacitors included. there are three of them mounted onto a small PCB. Between 1000-2000uf is ok.

What does it do? it helps supply instant burst of power to the ESC which can be a problem if the battery is to far away.


#3

The capacitor of course. I clearly wasn’t awake when I wrote this post…


#4

How short would the battery leads need to be to not require those capacitors?


#5

Good question @longhairedboy. I’ve wondered the same thing since my vesc is about 6cm from my battery series.


#6

@onloop thanks for clarifying, but I was looking for a more scientific insight.

Inquisitive as I am, I’ve gone ahead and Googled this and read up extensively.
Apparently the capacitor is there to smooth out ripples in the input voltage.

Some very relevant pages:


A theory on hill-climbing: MASSIVE 12s LIPO's, FOC, dual 6374, and the c-word
VESC - Too long of battery lead wires
#7

That makes a lot more sense. I’m familiar with power conditioning, and that’s what it looked like to me.


#8

Nice work @trbt555 Google is our friend… yeah i’m not the best person to explain electrickery mumbo jumbo… 18months ago i didn’t even know what an ESC was… all i know is the VESC feels amazing when riding…

I’m mostly a skateboarder!


#9

Yeah the cap (or caps in this case) are DC link capacitors.

They act as a filter for your noisey non smooth supply (Battery, power grid). They are more necessary in AC to ‘whatever’ converters (where supply is AC). But still useful to make a good BLDC controller when you have long wires etc.