two 5955 servos drag down a freshly charged A123 packs to 3.4V in flight !  
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All Forums >> RC Airplanes >> RC Jets >> two 5955 servos drag down a freshly charged A123 packs to 3.4V in flight !
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two 5955 servos drag down a freshly charged A123 packs ... - 6/22/2009 2:20 PM   
i3dm


 

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Status: offline 		Hey guys,

Sorry for the double posting but since the other thread is not getting a lot of hits probably due to its age, and the nature of this new problem has just taken one step closer to a solution, i think this is worth a new post !

Please read about it here:
http://www.rcuniverse.com/forum/m_8656930/anchors_8870925/mpage_4/key_/anchor/tm.htm#

How would you think that such a huge load could occur on the two 5955TG servos in flight ?
And here is the video:
[youtube] http://www.youtube.com/watch?v=kldZ84iCMts[/youtube]

thanks.


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RE: two 5955 servos drag down a freshly charged A123 pa... - 6/22/2009 2:36 PM   
digitech


 

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Status: offline 		Lior was there every anything you ever bought any good?.
seems bad luck is on your side here.....

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RE: two 5955 servos drag down a freshly charged A123 pa... - 6/22/2009 2:55 PM   
i3dm


 

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quote:

ORIGINAL: digitech

Lior was there every anything you ever bought any good?.
seems bad luck is on your side here.....


Yes, the kero burner i got from you is working great ! 

More seriously though, that was a very un necessary comment. i find it difficult to believe luck has got anything to do with this.


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RE: two 5955 servos drag down a freshly charged A123 pa... - 6/22/2009 3:13 PM   
SinCityJets


 

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Status: offline 		There is NO WAY your pack was drawn down to 3.5v. If anything, that was the voltage per cell. I'm not buying it.

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RE: two 5955 servos drag down a freshly charged A123 pa... - 6/22/2009 4:04 PM   
BaldEagel



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quote:

ORIGINAL: i3dm

Hey guys,

Sorry for the double posting but since the other thread is not getting a lot of hits probably due to its age, and the nature of this new problem has just taken one step closer to a solution, i think this is worth a new post !

Please read about it here:
http://www.rcuniverse.com/forum/m_8656930/anchors_8870925/mpage_4/key_/anchor/tm.htm#

How would you think that such a huge load could occur on the two 5955TG servos in flight ?
And here is the video:
[youtube] http://www.youtube.com/watch?v=kldZ84iCMts[/youtube]

thanks.



How many Mah where put back when you re-charged them? only that will tell you if what you found is true or your amp meter is on the blink, or your charger is not fully charging. 
This is the first time I have ever heard of anyone having problems with A123 Batteries, are you sure they are genuine A123's and not P04's.

Mike

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RE: two 5955 servos drag down a freshly charged A123 pa... - 6/22/2009 4:18 PM   
i3dm


 

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Status: offline 		These are Fromeco's genuine A123 packs (Iron Corps Extreme).

I think the voltage meter is not lying, and it might be a combination of high loads and not enough wiring to feed the Rx ?

I will see how much the pack charges back and let you know. i think its a spike current issue though, so i dont anticipate a high capacity discharge from the pack.


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RE: two 5955 servos drag down a freshly charged A123 pa... - 6/22/2009 4:59 PM   
mr_matt



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Status: offline 		What does that little blue widget actually do? Is it recording the lowest voltage seen since power up or something? Cause that voltage is going to be low for awhile while the device charges those caps (at least those look like caps under that blue shrink tubing).

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RE: two 5955 servos drag down a freshly charged A123 pa... - 6/22/2009 5:02 PM   
i3dm


 

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RE: two 5955 servos drag down a freshly charged A123 pa... - 6/22/2009 5:11 PM   
Gordon Mc



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Status: offline 		I might be missing seeing it (due to the horrendous way that the above webpage displays for me it's hard to read), but I don't see info on tha above webpage that explains what the display is.

Does confirm that those are honking great cap's though !

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RE: two 5955 servos drag down a freshly charged A123 pa... - 6/22/2009 5:16 PM   
i3dm


 

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Status: offline 		The manual explains that the display shows the real time voltage, and a click on the button takes you to the second mode, which shows the lowest voltage recorded since the last power up.

again, after the first flight the lowest voltage was 6.5V which is reasonable, second flight 3.4V !!

This definitely explains the lockouts i was expiriencing before (in my other post).


< Message edited by i3dm -- 6/22/2009 5:22 PM >

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RE: two 5955 servos drag down a freshly charged A123 pa... - 6/22/2009 6:10 PM   
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Status: online 		What does the voltage do when you stall the servo (as opposed to just twiddling the sticks)?



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RE: two 5955 servos drag down a freshly charged A123 pa... - 6/22/2009 6:20 PM   
Vincent



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Status: offline 		Sounds strange to me. Recently my friend Wayne brought out my new Mig-15 he had been working on for several months. I gave him a fully charged 2300 2cell 123 pack to use during the setup. Because he has no 123 charger he just kept using the batt during the whole time with no charge. When he brought out the jet to the field there was only 5% capacity left in the pack and the voltage was still 6.6v !!! we could not believe it because there was no visible performance difference between a charged pack and this almost dead one. I put 1900ma in it with my cellpro4 and flew the jet. These packs are awesome imo

V..


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RE: two 5955 servos drag down a freshly charged A123 pa... - 6/22/2009 6:41 PM   
i3dm


 

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quote:

ORIGINAL: siclick33

What does the voltage do when you stall the servo (as opposed to just twiddling the sticks)?




It goes down to 6.5V when i load both elevons by hand.


quote:

ORIGINAL: Vincent

Sounds strange to me. Recently my friend Wayne brought out my new Mig-15 he had been working on for several months. I gave him a fully charged 2300 2cell 123 pack to use during the setup. Because he has no 123 charger he just kept using the batt during the whole time with no charge. When he brought out the jet to the field there was only 5% capacity left in the pack and the voltage was still 6.6v !!! we could not believe it because there was no visible performance difference between a charged pack and this almost dead one. I put 1900ma in it with my cellpro4 and flew the jet. These packs are awesome imo

V..



Im charging the pack back up as we speak, lets see how much goes back into it.


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RE: two 5955 servos drag down a freshly charged A123 pa... - 6/22/2009 6:43 PM   
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Status: offline 		All I am saying is that if that little gizmo does not wait for that huge cap to charge it will read a low voltage.

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RE: two 5955 servos drag down a freshly charged A123 pa... - 6/22/2009 6:45 PM   
i3dm


 

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Status: offline 		Matt,
it starts counting AFTER the caps are charged.


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RE: two 5955 servos drag down a freshly charged A123 pa... - 6/22/2009 7:00 PM   
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Status: offline 		I'll back up the unlikelyhood of the pack being pulled down that low . You would need a dead short to generate the current that would depress the voltage that much . I doubt any of your small gauge wiring would survive that ! I fly electric aircraft powered by A123s and under a 50 A load I still get about 2.8V per cell . Try another battery and/or give that battery a good load and capacity check outside the airplane.

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RE: two 5955 servos drag down a freshly charged A123 pa... - 6/22/2009 7:08 PM   
R_Belluomini



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Status: offline 		I'm using a 2 cell 2300 in my Electra with mechanical retracts.  10 servos in total 8 of which are digital.
Each 7 minute flight consumes about 75 maH.


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RE: two 5955 servos drag down a freshly charged A123 pa... - 6/22/2009 7:20 PM   
olnico



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Status: offline 		If I understand well, you did the first flight with a full and fresh A123 pack. That draws around 150 mAh for 10 minutes from the pack.
So the pack was say 90% full after the first flight.
To get a voltage drop to 3,4V on these two cells pack ( 1,7 v per cell ), you need to draw 150A. This would have burned all you power supply cables...


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RE: two 5955 servos drag down a freshly charged A123 pa... - 6/22/2009 7:21 PM   
i3dm


 

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Status: offline 		Battery took back 374mAh after today's 2 flights (about 5 minutes each).

olnico - youre right and i agree with you. thats why im trying to figure what the heck is going on here.


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RE: two 5955 servos drag down a freshly charged A123 pa... - 6/22/2009 7:49 PM   
ianober



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Status: offline 		Sounds like your D-Cup is funky, try swapping it out with another one and see if you get the same reading.

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RE: two 5955 servos drag down a freshly charged A123 pa... - 6/22/2009 7:55 PM   
i3dm


 

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Status: offline 		Ianober, i dont think the DCUP is faulty, considering the low voltage lock outs i had before, and the red lights on the PB switch i had intalled earlier.


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RE: two 5955 servos drag down a freshly charged A123 pa... - 6/22/2009 8:01 PM   
ianober



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Status: offline 		Still I would rule it out, that reading does not seem possible with A123's.

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RE: two 5955 servos drag down a freshly charged A123 pa... - 6/22/2009 8:05 PM   
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Status: online 		How are you charging your A123 packs? Are you really sure they are fully charged?

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RE: two 5955 servos drag down a freshly charged A123 pa... - 6/22/2009 8:08 PM   
i3dm


 

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Status: offline 		Im charging them with the Fromeco A123 Ion Cube charger.
The DCUP read 7.0V when pack was full fresh after the charge so yes, they are full.

Im cycling the pack as we speak, its almost done discharging now. will post results soon.


< Message edited by i3dm -- 6/22/2009 8:16 PM >

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RE: two 5955 servos drag down a freshly charged A123 pa... - 6/22/2009 8:36 PM   
i3dm


 

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Status: offline 		AFter the charging which i did earlier, i just discharged the pack at 2A down to 5.3V as recommended by Fromeco.

Discharge took out 2070mAh. the A123 pack itself seems to be in perfect condition.


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