Does slow charge balance Lipo cels??? - Page 2 - RC Groups
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Mar 16, 2005, 12:13 PM
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Woo is good for laughs at PICNICS ...
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Mar 16, 2005, 12:19 PM
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Greatest Show in the World


Rd

U should come over and see the " FLYING CIRCUS" every weekend here at RSA next time U visit CA. I have a plane that U can finsh a RACE with, come on over and try it.
Mar 16, 2005, 12:23 PM
Repair Specialist
Ken-Ohki's Avatar
ok, at the risk of showing my ignorance, and perhaps hijacking the thread.

"WHY" wont 2 cells in a pack equalize? if one is 3.3 and one is 3.5. Why wont the 3.5 pack charge the 3.3 pack netting 3.4 volts a cell?? ( wile slow charging )

I have watched Nicads and nimhi's do this with my meter, why dont lipos?

And wile im asking and showing my ignorance... Just how does 1 cell give more then another cell causing the imbalance in the first place.


Ken-Ohki
Mar 16, 2005, 12:27 PM
Registered User
Only cells in PARALLEL equalize each other. Variations in internal resistance [I am told] cause cells to vary when charged in series.
Mar 16, 2005, 12:35 PM
Space Coast USA
hoppy's Avatar
[QUOTE=Ken-Ohki]ok, at the risk of showing my ignorance, and perhaps hijacking the thread.


And wile im asking and showing my ignorance... Just how does 1 cell give more then another cell causing the imbalance in the first place.
If you really want to know, read this: http://www.analogzone.com/pwrt0207.pdf

I have watched Nicads and nimhi's do this with my meter, why dont lipos?
NiCd and NiMH cells can dissapate excess charge energy by converting it to heat. Lipo's when subjected to excess voltages chemically and irreversibly degrade.
Mar 16, 2005, 12:38 PM
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Learn How to Slow Charge Using AF 109


Ken

When normal LIPO packs have been slighly over-stress, time is the magic ingredient to restore the cell back to its normal SOC ( stable open circuit ) voltage.

Further 1C fast charging will create more VOLTAGE GAP between cells and impede a normal fast charge 1C full charge. I have monitored this problem on the TAPs

A SLOW CHARGE at 50 ma -100ma shows a lesser " VOLTAGE GAP " level

But if U already have a defective overheated leaky tab cell, then no amount of any kind of charge gonna do anything.

That's why if a pack won't SLOW CHARGE, then its not normal. A good pack will pass a 3 " TIMEOUT" slow charge test using AF 109 in 3 hours

U should review my thread on Setting AF 10-9 for 9 hour Charge
Mar 16, 2005, 12:49 PM
Southern Pride
everydayflyer's Avatar
Yes slow charging my Li Poly batteries at between 0.2a and 0.3a (200-300mAh) does balance them to within ,closer than I can measure.

However there is a trick(?) to doing this. You must use some type of balancers which are connected to each cell of group of parallel connected cells.



https://www.rcgroups.com/forums/show...9&postcount=40
Charles
Last edited by everydayflyer; Mar 16, 2005 at 01:27 PM.
Mar 16, 2005, 12:59 PM
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Astrobob and I don't use any active balancing circuits, just the RIGHT current level
Mar 16, 2005, 01:09 PM
Crash Master
Gene Bond's Avatar
What Hoppy said.
Mar 16, 2005, 01:17 PM
Southern Pride
everydayflyer's Avatar
Quote:
Originally Posted by hall woo
Astrobob and I don't use any active balancing circuits, just the RIGHT current level
Astrobob Mr. Astro Flight ,Bob Boucher has never stated to the best of my knowledge that slow charging a LIPoly pack of series connected cells will balance them. You have been asked to supply proof of this numerous times. Where is the link to the post where Bob made such a statement. I have purchased and reads his books, I own several of his chargers, many of his Cobalt motors, and even a speed control or or two. I am very familiar with the vast knowledge he posses. In my eyes he is the father of electric flight.
It is very unfair and misleading to give the impression that he supports your notions.
Many of us here know about you and your alter ego but you could lead some newbie astray.

Charles
Mar 16, 2005, 01:41 PM
Permanently Banned
I was with him at Magnolia High School Electric Fly Event back in the 80s when he was developing COBALT motors and everyone was using ferrite 05 motors

I don't know if Bob ever said SLOW CHARGING balanced packs, only that we were able to restore packs back to normalcy SLOW CHARGING

IMHO, I don't think U need to worry about newbies understanding " CLAMPED VOLTAGE" since they probably don't even know how to use a DVM and how to check it for calibration.
Mar 16, 2005, 02:09 PM
Registered User
Quote:
Originally Posted by hall woo
I don't know if Bob ever said SLOW CHARGING balanced packs, only that we were able to restore packs back to normalcy SLOW CHARGING
It's nice that you are finally starting to be more clear about this. To be more specific, astrobob only said that he restored a pack that had been discharged to less than 3.0V per cell by slow charging it until it was above 3.0V per cell. Balance was never mentioned.
Mar 16, 2005, 02:26 PM
luc
luc
I plant balsa sticks too
luc's Avatar
yep, this is a classic procedure,...nothing to do with imbalance....
Mar 16, 2005, 03:40 PM
Flying motor mount master
fly_boy99's Avatar
Hall-

If you only fly your "CIRCUS" on weekends then I'll avoid RSA on weekends for now. Heck it's a zoo anyway and you can have it!!!

Who knows there might be a lipo "FIRE" act in your "CIRCUS"...

lol,
fb


Quote:
Originally Posted by hall woo
I was with him at Magnolia High School Electric Fly Event back in the 80s when he was developing COBALT motors and everyone was using ferrite 05 motors

I don't know if Bob ever said SLOW CHARGING balanced packs, only that we were able to restore packs back to normalcy SLOW CHARGING

IMHO, I don't think U need to worry about newbies understanding " CLAMPED VOLTAGE" since they probably don't even know how to use a DVM and how to check it for calibration.
Mar 16, 2005, 07:18 PM
Permanently Banned
Larry3215's Avatar
Just incase there is any doubt in anyones mind - I would highly recomend you take anything hall woo (or rcguy01 = same person) with a HUGE grain of salt!

Infact mabey even more than one or two grains

Larry


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