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Old Feb 16, 2006, 05:30 PM
Brit in NZ
RC-Tester's Avatar
NZ
Joined Sep 2005
508 Posts
EDF Profile?

Okay,

I've applied the 'EDF' profile to the first pack: the 3S Saehan 2100 'ProLite V2'. Waveform applied was:
  • 25.2A for 8 seconds
  • 42A for 2 seconds
  • Mean discharge of 13.6C

Usual graphs attached!

Rod
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Old Feb 16, 2006, 06:12 PM
Texas Ranger
Neil Walker's Avatar
USA, CA, San Francisco
Joined Aug 2004
2,524 Posts
Quote:
Originally Posted by RC-Tester
Neils burst profile:

Would anyone else agree that :

  • the common period for the average burst is approximately 20 Seconds?
  • on average the burst reaches ~42A
  • on averge the base level is ~ 20A
  • the burst duration is ~4 seconds
  • the base duration is ~ 16 seconds

This would give a synthesised profile of 16 seconds at 20A followed by 4 seconds at 42A.

Thoughts?

Rod


These were 2000 mah cells in a 2p configuration (a single 8s2p 4000mah TP ProLite pack).

Your profile seems reasonable to me, although I really have no idea what differences you'll see - in a "Real" flight the bursts are quite short, but more frequent... e.g. you would very rarely hold the collective wide open on this thing for 4 seconds. But whether you can say a bunch of short bursts equals one longer one... I haven't a clue. As you can see though, helis have quite a different profile than planks.

I didn't have the temp probes hooked up to the DPR during these flights but typical pack temps are around 125-130 after a hard flight (and timing the flight for 75%-80% of pack capacity). Ambient temps have been around 10 degrees C at flight time, and there is little to no cooling air. I expect it'll need some vents cut in the bottom of the canopy when summer hits to keep the cell temps down.


Edit: I think really the absolute values in this profile are kind of irrelevant, really. It's simply the ratio of base/burst time and base/burst/amplitude that is important. Looking at the cell capacity and absolute current numbers is not going to translate well to any other setup, because how over/under-powered the setup is will make a difference to those absolute values, e.g. you can't really look at this and say "helis average 5C and burst at 10-11C" because that's just how this particular one was set up... I would try to find a way to express your profiles without referring to absolute values.
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Last edited by Neil Walker; Feb 16, 2006 at 06:18 PM.
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Old Feb 16, 2006, 06:35 PM
Texas Ranger
Neil Walker's Avatar
USA, CA, San Francisco
Joined Aug 2004
2,524 Posts
Here's two more for you:

- A .60-size lb 3D plane
- A 60" warmliner

Both are DPR files and the description of the power system and cells used are embedded in the DPR files. The 3D plane was over 200 watts/lb and the flight recorded I would call "moderate 3D"; it was a flight with a whole variety of maneuvers but it could have been beat on harder if one really wanted to. The warmliner profile is where I would say ignore the abislute values.. as far as raw power/weight goes this one isn't terribly exciting - but the profile of the bursts is pretty standard. Obviously higher power though is going to mean shorter bursts... typically anywhere from 10-15 seconds for this down to 3-5 seconds for the crazy ones. The time between bursts would be similar.
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Old Feb 17, 2006, 05:56 AM
Giz
Tony Rogers
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Bath, UK
Joined Sep 2003
2,194 Posts
Quote:
Originally Posted by RC-Tester
Okay,

I've applied the 'EDF' profile to the first pack: the 3S Saehan 2100 'ProLite V2'. Waveform applied was:
  • 25.2A for 8 seconds
  • 42A for 2 seconds
  • Mean discharge of 13.6C

Usual graphs attached!

Rod
Just a quick observation. The end temperature is again similar but slightly higher than the interpolated value from the constant current discharge test. From this, perhaps we can conclude that the temperatures reached during a constant current discharge, where the discharge rate equals the average current draw in the aeroplane, are reasonably representative of the temperatures that can be expected in practice.

The temperature plots that you are showing in this thread allow us to check the temperature at 85% discharge. So, if I were choosing a pack for a new application, I can check the discharge curve for the expected average current draw and make sure that the temperature will be within limits. That's very useful.

Edit. Oh and the temperature curve is roughly linear so I can work out the expected end point temperature for 85% discharge from the temperature delta.
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Last edited by Giz; Feb 17, 2006 at 06:06 AM.
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Old Feb 17, 2006, 07:29 AM
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Mister UHU's Avatar
London UK
Joined Dec 2005
394 Posts
Quote:
Originally Posted by RC-Tester


As the first steps are done for the three profiles

- filtered at 0.2Hz,

and FFT of the signal. (attached)

Rod


Hi Rod,

Sorry but my brain is a bit rusty,
so could you please explain in layman's terms
what data processing you have done and why,
so I can check that I am following your reasoning correctly.

I think it would also help any post-readers that aren't familiar with FFT etc.

Thanks.
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