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HelicopterScale Model RC Helicopters › Battery C Rating
12-18-2016 05:57 PM  6 months agoPost 21
Mojave

Elite Veteran

Palos Verdes, Ca. USA

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Well stated opinion Sandy...
Barry

All helis and planes have an expiration date stamped on them...you only find it after you crash!!

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12-18-2016 06:15 PM  6 months agoPost 22
TailKiller

Senior Heliman

Panama City, FL

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Makes sense to me.. I need to quit being cheap.. lol Thanks Sandy

,Dennis
http://pcrcheliclub.com/
700 Astar Super Scale T-600 Bell 206 Trex 600 Naza H DX8

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12-18-2016 07:08 PM  6 months agoPost 23
ICUR1-2

Elite Veteran

Ottawa, Ontario

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one last time for the old dogs

Amps out= c rating X mah

as your mah drops so does the amps out.

spending time, paying attention

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12-19-2016 12:01 AM  6 months agoPost 24
Phoenix NOTARSenior Heliman - State College, PA USA - My Posts: All  Forum  Topic

Dear Mr. ICUR1-2,

I am sorry, but my helicopter does not operate to your capacity reduction theory.

The graphs below are from a Castle Creations ICE2 160 HV ESC running 2 x 5S 8000mAh 30C Zippy battery packs connected as 10S. The helicopter was my incredibly power hungry Electric MD900 NOTAR.

I think that we can all agree that when I connected the fully charged battery packs, I could have in theory “pulled” 240 amps out of them for a short time. As I understand your posts, as the helicopter was flown, and I used some of the batteries 8000mAh capacity, the amount that I could “pull” from these packs would be reduced. So, after I used 4000mAh worth of fun, I would only be able to “pull” 120 amps out of the packs, and when I used 90% of the 8000mAh capacity (800mAh remaining) I would only be able to pull 24 amps out of these 30C packs.

Well, the charts show that on the 2nd flight (fresh 8000mAh 30C batteries installed) I flew for 302 seconds (302 -604), and the average amp draw was 84.9 amps / 3112 watts for theses 302 seconds (5 minutes). I am not sure why the Castle ESC did not reset the total mAh consumed for this flight, but it started at 4.23 consumed, and ended at 11.40 consumed, so this flight consumed 7.17 Ah as shown by the logs. If you do the calculation directly based on the 84.9 average amp draw for the .083 hour flight it calculates to 7.12 Ah, so pretty close.

If you look at the helicopters ACTUAL in flight consumption at the end of this flight (where the curser is shown) I was STILL DRAWING 93.3 AMPS / 3215 watts (at 34.4 volts) as I was landing. I actually only had 8.9% of these 8000 mAh packs left, yet I was still “pulling” 93 amps out of them.

So I guess “Old Dogs” win this round, even If I am not yet as “old” a dog as Peter.

Sandy

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12-19-2016 12:08 AM  6 months agoPost 25
Phoenix NOTAR

Senior Heliman

State College, PA USA

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2nd try at a clearer graph upload

Sandy

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12-19-2016 12:38 AM  6 months agoPost 26
Phoenix NOTAR

Senior Heliman

State College, PA USA

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If someone has a suggestion of a better way to get a castle log posted to RunRyder in a more legible format please let me know.

I have saved it as up to a 3 meg PNG file, but when up load it to Runryder it gets reduced to a file only about 200 kb in size.

Sandy

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12-19-2016 01:36 AM  6 months agoPost 27
ICUR1-2

Elite Veteran

Ottawa, Ontario

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If you look at the helicopters ACTUAL in flight consumption at the end of this flight (where the curser is shown) I was STILL DRAWING 93.3 AMPS / 3215 watts (at 34.4 volts) as I was landing. I actually only had 8.9% of these 8000 mAh packs left, yet I was still “pulling” 93 amps out of them.
you drain them that far down If you like puffy batterries that's your choice but I stand correct

amps out = c X mah
you can't change that fact

spending time, paying attention

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12-19-2016 01:55 AM  6 months agoPost 28
littleman

Key Veteran

Pasadena, Ca

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but I stand correct
*corrected

Proud member of Teams Castle, MSH USA, Futaba, Scorpion, & Nick Maxwell Products

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12-19-2016 02:25 AM  6 months agoPost 29
ICUR1-2

Elite Veteran

Ottawa, Ontario

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littleman

^ LOL

geesh where are these democrats coming from ??

spending time, paying attention

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12-19-2016 03:56 AM  6 months agoPost 30
littleman

Key Veteran

Pasadena, Ca

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Ok, I'm 27, so let's try it from the mouth of a young dog. As a disclaimer I fly 3d not scale, so I tend to *ahem* utilize the C rating of the packs (and annoy Peter )

In the attached log, I was using a 5000 mAH 45 C pack. Per the log I had discharged the pack 2.23 Ah, making the pack a 1.77 Ah pack still at 45C. This means that the pack provide 124.65 Amps, which makes the 99.9 Amps I was pulling at that moment pretty darn close to the pack bursting into flames.

BUT this information isn't 100% accurate. The reality is that I put 3690 mAH into this battery (in 3 minutes which leads credence to the amount of amps that I'm drawing) Lets assume for a second that this 100 amps is correct and I had actually consumed about 3500 mAh. This means that the pack can only provide 67.5 amps, but I managed to pull 100 Amps. So either these packs are underrated (seems like a pretty horrible marketing strategy) OR your logic is incorrect.

Other semi pertinent information includes that I am running on 12S, and the RPM is set to 2100, so there wasn't a whole lot of RPM loss considering I had theoretically just ruined the pack, for about the 40th time since I reproduce something similar to those logs every single flight and that was the 40th cycle of those packs

Proud member of Teams Castle, MSH USA, Futaba, Scorpion, & Nick Maxwell Products

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12-19-2016 08:54 AM  6 months agoPost 31
Andy01

Senior Heliman

Brisbane, Australia

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I think this argument is somewhat irrelevant because there is enough of us who have been there and done that to know the truth.

Proof of the pudding is in the eating so they say

I have been running my lipos to between 70-80% discharged with a few exceptions where I forgot to start the timer since 2010.

I have six Turnigy 25C 5000mAh 6s (the cheap basic blue ones), and I have charged them after flying and stored them fully charged since new. I have always worked on the full rated capacity x C rating but I also fly sedately and seldom draw over 25A anyway.

These 6 lipos still run a IR of between 6 and 10 milliohms (according to my Hyperion Duo II) per battery (not per cell) depending on whether it is summer or winter (the IR is a bit higher in cooler weather), and I have logged every parameter on every lipo since new, so I have a full history on each. So they are what I would regard to be in pretty good condition in spite of;

- being stored fully charged
- being inadequately rated (according to a poster above)
- being occasionally over discharged
- being more than 6 years old
- having more than 60 cycles each (yeah, I know - I don't fly enough)

So, some actual real world facts would tend to indicate the following;

- storing fully charged is NOT a problem if they are frozen
- they are, in fact, adequately rated at a lowly 25C
- occasional over discharge is not a instant killer
- age is not really important (applies to people as well)
- I don't fly enough

So perhaps we should leave the debate there

TK

To answer your question. To me the benefits of storing fully charged and frozen is that;

1. I don't have to wake up at the crack of dawn to get my six big lipos through my 2 channel Hyperion to charge them before flying.

2. If I decide not to fly (discharge) them all, no biggie

3. If something happens (like the weather changes, or it gets windy), I don't have to discharge them and add another cycle to them before storing.

I live in Brisbane (Australia) where winter is around 65°F and summer gets up to 100°F, and I learnt the hard way when I "cooked" 4 little 3s lipos in 2009 by storing fully charged (twice) for 3 weeks at a stretch in summer due to unforeseen circumstances.

For interest, I broke my wrist earlier this year and did not fly for over 5 months. The first flight out they were a little "soft", but after that they were back to normal - after 5 months fully charged in storage.

I always give them at least an hour or so to "defrost", I wipe them dry (condensation), and fly. I do NOT fly them cold, and do not charge them cold.

Colin

Vario Long Ranger 700e
Seahawk 600
UH-1N 500
Baumann EC-145 800+ (coming soon )

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