Nov 22, 2013, 03:39 PM
Pattern Pilot
Question

# Forecasting too high a ripple ?

I've been surfing this forum on how a too high ripple voltage will impact an ESC. I think I understand how longer leads will impact the inductance and thus the ESC and the solution is to add caps inline.

But I also see a lot of other things like high resistance (tired, low C rating) batteries, poor connectors (again high resistance), arming systems (yet more resistance) and longer leads (resistance and inductance) causing the ESC fits.

I've seen answers for longer leads limits before inline caps are required, but my question is:

Is there a definitive approach to adding up all the resistance up stream (ESC to battery) that one could use to determine that the ripple ration could be in jeapardy?

Or, am I over simplifying a complex issue?
 Nov 22, 2013, 05:12 PM A man with too many toys As I recall someone from CC said that ripple over 10% could cause FET failure if running close to the max current limit. In that case the ESC would just stop working. I have never had any problem getting over 10% on any of my airplanes or helicopters and a couple of them have over a foot of wire. Run some tests and look at the data log – you may not need any extra capacitors. You could calculate a theoretical ripple number but measuring all the component resistance accurately is difficult and takes some expensive equipment. Much easier to just run some short bench tests and look at the data log. .
 Nov 22, 2013, 05:14 PM A man with too many toys One other thing to consider is that the ripple depends on the PWM frequency at part power and commutation frequency at 100% throttle. .
Nov 23, 2013, 10:58 AM
Pattern Pilot
Quote:
 Originally Posted by RC Man ... You could calculate a theoretical ripple number but measuring all the component resistance accurately is difficult and takes some expensive equipment. Much easier to just run some short bench tests and look at the data log. .
I have been faithfully following the data log, but that is more "real time". I was thinking more a long the lines of "predicting" a troublesome situation.

Let me explain where I'm coming from. Back in Sept. I went through three Phoenix ICE2 HV80 ESCs in about a three weeks time. The first occurred the day prior to a contest at the contest site. I had just taxied out, turned at the end of the run way; no problem. As I started to throttle up to take off, I was greeted with a pop, a belch of flames and smoke. The plane a little charred but OK. The ESC toast. That was ESC #1.

A friend at the contest loaned me his spare HV 80 which worked just fine for the rest of the weekend. The friend suggested that I keep his ESC until the next contest. Which I did and while practicing the next week his ESC started going into "hard voltage cutoffs". Same result with every battery I owned, new and old. So much for #2.

An other friend let me use his HV 80. That worked for about another week, until it just flat out quit, with no warning. #3 gone.

By this time I called CC for help. After he (Bernie Wolfard) listening to my plight, suggested that it was my connectors explained the effects of ripple voltage. I had been using Anderson Power Pole 45 amp. connectors exclusively. I then replaced them all with Dean's and this is where I am currently.

I am flying with ESC #4 the replacement from CC for #1, it was still under warranty, and Deans connectors. So far so good.

I still follow my data logging religiously, but with much more attention to the ripple.

I started this thread with the intention of a better understanding of ripple.
 Nov 23, 2013, 11:37 AM A man with too many toys The new Edge has new hardware and larger capacitors. It would be nice to hear is any of them have a ripple problem. It would be nice to get someone from CC involved in the discussion but it seams that they don’t support the forums much any more. ?
Nov 23, 2013, 02:22 PM
Pattern Pilot
Quote:
 Originally Posted by RC Man The new Edge has new hardware and larger capacitors. It would be nice to hear is any of them have a ripple problem. It would be nice to get someone from CC involved in the discussion but it seams that they don’t support the forums much any more. ?
Yes, I was hoping that Bernie would jump in here!!! It is also my desire to help nay sayers understand the issues that they themselves impose upon ESCs.
Last edited by BuffBuilt; Nov 23, 2013 at 02:28 PM.