Castle Cap Pack

[cudaboy_71]

Originally Posted by lazor 22

If are wires are good without the cap pack, but when added, they are to long should we add the cap pack?

how is that even possible? you measure from the cap pack to the batteries. adding the cap pack can't make the wires longer

[lazor 22]

Yea but it was outlined in his drawing so it must have something to do with it... I'm having trouble though do we measure from the battery side or from the esc side?

[cudaboy_71]

in your case i think it'll be easier to extrapolate the electron capacity between the cap pack and the ESC (based on the calculated capacity of the cap pack itself) and divide by the inverse of their squares. then, just double that length and shorten by log(e)...but, only the black wire.

[lazor 22]

Hmm I didn't think of doing it that way, much easier to understand. Why could you not have just said that in the first place Vico and not confused so many people??

[Vinger]

Originally Posted by SkinWalk3r

Awwwww crapppp...

I just read this thread and measured my leads....between the kontronik 120 hv and my 12s batts is over 13" !!!!!

I have been flying my heli - 20 to 30 flights like this....no hard stuff. Flips and rolls.....how much damage to my kony have I caused

No damage, Kontronik does not need this

[Airworks]

i saw the funniest heli ive seen i thinkin this thread! my god........what are you thinking!

[BatteryKing]

Well here is something I was pondering: What is the amperage wave form coming from the ESC under load? If I remember my BLDC reading correctly these speed controllers send out a triangle wave form to the motor. If there is no filter in the CC ICE, this would mean a triangle power wave form would be going to the battery. In my CC ICE logs it looks like the voltage sag is the same as the ripple and I am seeing up to 2.6V drop on a 22.2V setup, so it is a very measurable amount. (The bad thing is I have short, thick gauge wires already, it is just the packs are going south.) This would suggest that a wave form from zero amps to max amps is going to the battery and at max amps there is maximum voltage drop while at zero amps the voltage fully recovers as far as I can reasonably tell. Assuming the aforementioned triangle wave form, this would suggest a 50% power factor on the battery for a given usable C rate seeing that C rate is based on internal resistance of the battery and associated usable level of voltage drop.

Considering all of this, if you are limited by the battery IR (internal resistance) and/or you just want to be kinder to the battery, wouldn't a capacitor setup increase your effective C rate or lower peak amp draw from the battery as you are drawing power from the battery more continuously at a high power factor and buffering it in the capacitor as opposed to more intermittently at a lower power factor by closely following the triangle wave output to the BLDC motor?

[BatteryKing]

I found a youtube video where someone hooks up an oscilloscope to take a closer look at the actual wave form a brushless ESC puts out. It looks like I gave a way too simplified explanation as really what the oscilloscope output looks to me more like a combination of short square pulses, some trainglish which is squared off, and all kinds of other little crazies, the extent of which is hard to determine.

YouTube

YouTube

[nmdesertracer]

That guy has way to much time on his hands!

[davehour]

The brushless ECS's we now use in our hobby work by Pulse Width Modulation (PWM). The output signal of the brushless ESC's isn't a sine wave, but a square pulse train whose width is changed to "resemble" a sine wave output to the motor load. The frequency or pulse repetition rate of the square pulses train is set and then remains fixed. This is why we can choose different PWM frequencies in some ECS's. By changing the width of the pulses in a defined way, the average value and rms value of the output signal is changed, hence changing the speed of the motor. The process is more involved but the basic explanation given above gives the general idea.

David

[BatteryKing]

Well I soldered in the CC CapPack right next to my CC ICE 100 and brought it up for a spin. Before wiring in the CC CapPack I was seeing a 2.6V drop in my logs around 100A and my ripple and voltage drop tended to be the same number. Now at 100A I am seeing a 1V drop and a 0.5V - 0.6V ripple. Doing hard maneuvers it sounds and feels a lot stiffer. I am also not tripping my low battery alarm in flight (using a Hitec Aurora 9 radio with the Optima 7 SPC port directly connected to the main battery connector) on hard maneuvers like I was before. It seems wiring up the CC CapPack has breathed new life into my quickly aging nano-tech batteries.

I attribute this effective C rate increase I am seeing to the BLDC motor and ESC pulsed nature of operation and henceforth effectively low duty cycle being transmitted to the battery for lack of effective filters without the CC CapPack. Seeing that all hobby LiPos have internal resistance meaning if you say draw 200A on a 1ms pulse with a battery R rating of 0.010 Ohm, you will have a 2V drop. At 24V no load, this would bring you to 22V across the terminals of the pack during the pulse and then back up to 24V when the ESC shuts off again. (Causing a 2V ripple.) However say there is some space between each 1ms long pulse (say 1.5ms) and a capacitor with almost no resistance, as it is just basically two opposing metal plates conductivity wise, wired in parallel to the circuit is given a chance to charge up to say 23.5V while the ESC is effectively off between pulses. At this voltage the capacitor would be charging at a rate of 50A (0.5V drop across the battery at 0.010 Ohm with the equation of I = V/R). During the 1ms long pulse while the ESC pulls 200A the capacitor discharges to 23.0V. At this voltage level the battery is delivering 100A (via the equation of I = V/R) and the capacitor is delivering 100A. The ESC shuts off so now the capacitor is charging at 100A because at this moment in time the battery still has a 1V drop across its terminals due to the capacitor being partially discharged to 23V. While the ESC is off (for say 1.5ms) the capacitor charges back up to 23.5V and the charge rate drops to 50A again when the next 200A ESC pulse comes and the cycle repeats.

To summarize without the capacitor the battery experiences a 200A load and a 2V drop for 1ms and then experiences a 0A load and 0V drop for 1.5ms in this model. With the capacitor the battery experiences a continuously changing load from 50A to 100A with the voltage drop varying between 0.5V and 1.0V.

While I am not factoring in all of the variables nor integrating to give you real exacting numbers, does this basic working model reasonably represent the reality of what is going on?