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Old Nov 15, 2012, 07:20 AM
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Lipo Does not balance

Hi,

I have a new lipo (1800mah, 3s, 25c) that does not balance after it was charged for two hours. Two cells shown full 4.2 v but the third one only showed 3.9v. Is there a way I could balance this lipo, or is this a bad one? I use 306B charger. Any advices would be appreciate it.

Thanks.
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Old Nov 15, 2012, 07:53 AM
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Haralson County GA. USA
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Make an adapter such as this with whatever connector matches you chargers output and the LiPolys balancing leads. Connect to the low cell and set charger to 1S and charge until it matches the others.


http://www.rcgroups.com/forums/attac...7&d=1297609335


There is no real standard for the balancing leads color code however most do have a Black lead on one of the most outside position. This balck lead (battery negative) and the next one is cell #1 , The one next to the black and the next one is cell #2 and so on.


A very good interactive site here

http://scriptasylum.com/rc_speed/lipo.html


Charles
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Old Nov 15, 2012, 08:01 AM
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As Charles said you can charge just that cell through the balance leads if you make an adapter. This is also a good site:
https://sites.google.com/site/tjingu...ce-connectors/

What were the voltages when you got it? You should always check the pack with a cell meter right when you get it before doing anything to verify that it is good.
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Old Nov 15, 2012, 09:44 AM
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Issues like this make it nice to have a Cellpro 4s charger sitting around. They charge each cell individually.
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Old Nov 15, 2012, 10:20 AM
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Well yes and no. Simple fact is they like many other chargers which charge thru the balancing leads it charges thru the two outermost leads and balance by discharging thru a combination of the leads.

I am very supportive of FMA chargers but it a simple adapter other chargers can do the very same thing.

Charles
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Old Nov 15, 2012, 11:17 AM
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Lipo Does not Charge

Hi Everyone,

Thanks a lot for your advices. I appreciate them.
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Old Nov 15, 2012, 11:21 AM
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Quote:
Originally Posted by everydayflyer View Post
Well yes and no. Simple fact is they like many other chargers which charge thru the balancing leads it charges thru the two outermost leads and balance by discharging thru a combination of the leads.

I am very supportive of FMA chargers but it a simple adapter other chargers can do the very same thing.

Charles
Actually Charles the manual states in it's feature list:
Quote:
Each cell is charged independently, providing exceptional charging safety and elevating RC packs to the safety level of cellphones.
I doubted it too so I had to go look.
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Old Nov 15, 2012, 12:44 PM
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The 'feature list' is misleading. Cellpro's work like most lipoly chargers in that there is a single charge circuit and voltage of each cell within a series pack is monitored / adjusted to yield a balanced pack upon completion of charge. They simply provide charge current via the outermost balance leads rather than main charge lead.

That said, there are a few chargers that have truly independent charge circuits. The original DN charger and CSRC charger are most notable.

I have purchased several of these to give to friends who wanted a very simple and very safe charger. It has 4 discrete charge circuits and works extremely well, albeit with relatively limited current.

Mark
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Old Nov 15, 2012, 02:49 PM
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Quote:
Originally Posted by mrforsyth View Post

I have purchased several of these to give to friends who wanted a very simple and very safe charger. It has 4 discrete charge circuits and works extremely well, albeit with relatively limited current.
Mark
I have one of the Hextronics. I use it a fair amount for charging small 2 x 2S at the same time. Putting a watteter line I found the actual charge rate is about 2/3 of claimed. It also charges to about 93% by cross reference with my Cellpro 4S. No biggie-I just top them if I want to.

Not a great charger but it does seem to work reliably and is pretty simple. Kind of a top of the bottom sort of position.
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Old Nov 15, 2012, 03:42 PM
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grimbeaver

One would need to go to to when the CP4 was first introduced. There were very,very few balancing chargers period . The then owner and founder of FMA Fred Marks was extremly proud of his creation to the point that he often posted it was so safe just set it and forget it. Non the less fact is it is a whole batteries(cells in series) charger and indivual cell balancers . As Mark posted very few true multi channel LiPoly chargers that is ones that contain multi charging circuits (one fotr each cell) in a single case. I also have a DN Power charger and it does work extremely well especialy with LiPolys with greatly inbalanced cells. It use to be my go to with such LiPolys until the FMA chargers with 1A of balancing power per cell came along.


Charles
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Old Nov 15, 2012, 04:06 PM
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it was so safe just set it and forget it.

Charles
or
"Plug-and-play and walk away"
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Old Nov 16, 2012, 05:32 PM
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Quote:
Originally Posted by grimbeaver View Post
As Charles said you can charge just that cell through the balance leads if you make an adapter. This is also a good site:
https://sites.google.com/site/tjingu...ce-connectors/

What were the voltages when you got it? You should always check the pack with a cell meter right when you get it before doing anything to verify that it is good.


What would the characteristics be for a bad cell? Just that one is at a drastically different voltage than the others?
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Old Nov 16, 2012, 05:36 PM
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Bad cell = Low capacity or high internal resistance with respect to other cells. Arrival voltage does not tell one much at all unless it's below 3.7 volts.

Mark
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Old Nov 16, 2012, 05:53 PM
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The equipment used at the manufacturer to charge / cycle the new cells ios very expensive and accurate equipment. All of the cells are(were) charged to the same voltage. There are only few logical reasons for one or more cells to be lower than the others. The cell has issues is defective as in has a bad seal,internal short etc.. or it was shorted ,briefly during pack assembly. I have LiPolys which have stayed charged and balanced for years . No way that a healthy LiPoly cell self discharges a few tenths of a volt or more in a month or so.

Charles
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