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Jan 20, 2020, 05:53 PM
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atreis's Avatar
True, but whether or not they adjust timing, they very likely don't adjust it to match that of another arbitrarily chosen ESC. IMO, it's more important to get a practical measure of which one is better as they would be applied in the real world, and not a theoretical one.
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Jan 20, 2020, 07:49 PM
aka JetMan Joe
MCSGUY's Avatar
Thread OP
Quote:
Originally Posted by prototype3a
For what it's worth, I think you're reaching the wrong conclusions here because no two brands of ESCs measure timing the same and timing effectively changes the kv of your motor by 10-15%. So, to really compare these would require adjusting the timing of the ESCs to achieve the same RPM and then maybe compare how much power each ESC required to hit that rpm.
I always tweak the ESC's to deliver the highest RPM possible using the available parameters, timing being the dominate one. The APD does not provide access to timing parameters. At a low level one can tweak PID parameters however they deal specifically with velocity stability as one would expect of an ESC developed for Quad use. Those settings were remarkably well set, to the point the unit was stable and solid down to about 10-20 RPM and made it extremely difficult to stall the motor by loss of synchronicity.

Joe
Jan 20, 2020, 11:06 PM
dnn
dnn
Registered User
Quote:
Originally Posted by MCSGUY
One of the things the years of testing have provided us is a good idea which brands itís reasonably safe to trust. While C ratings have become a marketing posture for most, capacity numbers have been fairly accurate across the board. And Dinogy in general has been one of the good guys.

However itís my position that the type of high amp usage that sucks the voltage down to the floor levels out much of the usable difference between a 5000-6000 mah pack unless itís a strong real C unit. For my type of EDF and flying style I find I get more flight time out of a 5000 heavy Graphene then a 6000 light weight pack.

Joe
Thank you Joe for actually providing an informational response.
Jan 20, 2020, 11:11 PM
ancora imparo
jj604's Avatar
https://www.rcgroups.com/forums/show...-Overdue/page4

Quote:
Originally Posted by John61CT
Good stuff!

How's the Figure of Merit calculated again?
Jan 21, 2020, 01:26 AM
aka JetMan Joe
MCSGUY's Avatar
Thread OP
Quote:
Originally Posted by prototype3a
I would argue that most people don't adjust timing because they don't actually understand what the setting does.
HaHa, I just picked up on this. My education is in control systems engineering having spent a significant portion of 35 years developing and tuning first industrial process control systems and later high speed servo positioning systems for maximum through put and stability. I’m laughing because your post made me realize my ingrained obsession to tweak, tune, poke, test or calibrate anything with a knob, display or data port is probably not typical RCist behavior

For no other reason then to bloviate, in simplified terms timing involves finding the “sweet spot” where the rotating electrical field “leads” the rotors magnetic field enough to pull as aggressively as possible without overloading the system.

Joe
Last edited by MCSGUY; Jan 21, 2020 at 01:43 AM.
Jan 21, 2020, 06:43 AM
Registered User
atreis's Avatar
I've adjusted the timing on some of my models - ones where I actually care about getting every last bit of performance - but that's not even a majority. For most it just isn't worth the effort. (Who especially cares if a floaty scale arf that's meant to fly slow has perfect timing?)
Jan 21, 2020, 12:23 PM
big ignore list/drama is dumb
brushless55's Avatar
Quote:
Originally Posted by John61CT
Sure, if you discharge at a low enough C-rate.

But in normal use only use 5000mAh.

Best to start a new thread if you want to discuss.
Quote:
Originally Posted by Ohmic
Have you personally run a capacity test on the 65C battery dnn is asking about?
Quote:
Originally Posted by John61CT
Yes, the mAh numbers are "honest" in the sense that at a low rate discharge you can hit the rating or very close.

That does not mean you will get that capacity at high discharge rates, certainly not over 1C.

Note that if getting highest possible capacity (energy density) is really your goal, for a low C-rate use case, then you should not buy chemistries optimized for (low IR high C-rate) **power** density, since the two goals are in opposition to each other.

I've done extensive capacity testing at 1C ratings and found Labels or "Brands" to be 10% less of the Art Work (printed label) on some of the 6000 to 6500mAh packs, the same as if I ran them at a 20C load and 10C loads, still 10% less than what was printed on the labels..
Most of the 5000mAh packs tested at 30C, 20C, 10C all showed the same capacity of around 1% difference.
The most consistent findings were the bigger "lightweight" packs almost always showed to be of less capacity vs the heaver batteries tested.

Also with some 4000mAh packs I raced with while running in parallel, acted as thought I was not getting a real 8000mAh of capacity during a race but maybe 7000mAh in total...
never thought of testing the capacities of those
Jan 21, 2020, 01:03 PM
Which one is aileron again?
Quote:
Originally Posted by MCSGUY
For no other reason then to bloviate, in simplified terms timing involves finding the “sweet spot” where the rotating electrical field “leads” the rotors magnetic field enough to pull as aggressively as possible without overloading the system.

Joe
That's a really good way to describe it.

I work with students so one of my "jobs" is often thinking of clever ways to describe complex things in a way that the students can easily understand.

I've often compared the ESC/motor system to that of pushing someone on a swing. A " commutation error " is that event when you catch the person on the swing with your face.


For what it's worth, when I'm testing power systems, I really prefer to use a power supply in an attempt to tightly control the input voltage to the system. But I also understand that a 15kw 50v constant voltage PSU is not an inexpensive or widely available piece of kit.
Last edited by prototype3a; Jan 21, 2020 at 01:10 PM.
Jan 21, 2020, 01:49 PM
Professional heli wrecker
Luvmyhelis's Avatar
In constant gov'd setups that way of setting up is ideal. However waay back in the dark ages when i started custom building motors. I remember talking to Dan at GoBrushless, who told me to hold the motors by hand and test them through the entire unloaded rpm ranges. This way you actually feel the stutter happen and tune that out. If it runs clean unloaded, it will run clean loaded. This was well before I was running extensive vibe logging on motors to fine tune them. One thing I quickly found out, no two 'identical' motors run the same, and no two esc's run the same. So one guys settings almost never work for another trying the same thing.
I constantly tell guys who ask me what my final settings are, that they need to put in their own work. And why. I never hear back from them.

I never use power supplies, as they never ever translate into real life performances. Use the batteries you are going to run on the system you are going to fly or drive or whatever. As those will most certainly change the equation as they influence everything.
Jan 21, 2020, 02:21 PM
Registered User
"HaHa, I just picked up on this. My education is in control systems engineering having spent a significant portion of 35 years..........."

Joe,
I sincerely appreciate the "tech speak" that goes on in this thread though I freely admit most of it is well out of my universe of understanding. I may not be typical but i'd guess i'm pretty close in that i can't think of one instance where i even tried to change the timing on an ESC/motor combo. I'm not concerned about getting the very last ounce of thrust but fully support those who do since they provide good and tested information that benefits me and the product.
Your battery testing and information sharing has saved me personally and i'm sure many more
lots of money and provided product satisfaction as well. So to you and all the contributors on this thread thank you and keep the info flowing.
Jan 21, 2020, 06:56 PM
aka JetMan Joe
MCSGUY's Avatar
Thread OP
Quote:
Originally Posted by atreis
I've adjusted the timing on some of my models - ones where I actually care about getting every last bit of performance - but that's not even a majority. For most it just isn't worth the effort. (Who especially cares if a floaty scale arf that's meant to fly slow has perfect timing?)
I have to agree in general. With sport ESC's like Castle, Hobby Wing, etc. it's hard to see much difference which I've always attributed to limited control resolution or precision. However when I've run into mechanical overload where the motor loses syncro and squeals, being able to retard or reduce the timing value (decrease the lead angle error) will often resolve the issue.

Otherwise the only time I encountered a significant performance impact was using a Kontronik Kosmik 200HV with a Stumax SM110 4 Blade fan built to see if a Spark could break the 225mph barrier. Using the Kosmik's auto tuning default was delivering pathetic results so by gradually incrementing the tuning value (to some stupid high extreme) it was possible to increase the loaded velocity by over 3000RPM on 14S.

Joe
Jan 21, 2020, 07:13 PM
aka JetMan Joe
MCSGUY's Avatar
Thread OP
Quote:
Originally Posted by prototype3a
For what it's worth, when I'm testing power systems, I really prefer to use a power supply in an attempt to tightly control the input voltage to the system. But I also understand that a 15kw 50v constant voltage PSU is not an inexpensive or widely available piece of kit.
I'm also in the field accurate camp however Schubeler's published thrust curves for their fans is based on constant voltage as opposed to the real world of Lipo voltage sag. Once I realized that I started adding an extra cell to any high performance requirement using one of their units.

Joe
Jan 21, 2020, 08:37 PM
Which one is aileron again?
Quote:
Originally Posted by Luvmyhelis
I never use power supplies, as they never ever translate into real life performances. Use the batteries you are going to run on the system you are going to fly or drive or whatever. As those will most certainly change the equation as they influence everything.

I don't have this problem but I also developed a mathematical model for the motors I'm testing and running which is accurate within a few percent.
Jan 25, 2020, 11:52 AM
aka JetMan Joe
MCSGUY's Avatar
Thread OP
Jack's updated https://www.liporatings.com It's looking good (as always)!

Joe
Jan 26, 2020, 06:28 AM
Registered User
Thanks Jack for the update on the Lipo Ratings. Great work Joe, Rick and all the individuals that post great data on this site.


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