Lipo Battery.

Old 02-11-2011, 02:47 AM
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Default Lipo Battery.

Hi guys, need advise about lipo battery. I have 1 3S lipo where it seated on shelf around 1 year and when I charge it with lipo balance mode....it only detect 2S instead of 3S. I try to use Ni-Mh to charge it till 9.2v and go back using lipo balance mode and I can see 1st 2 cells voltage at 3.9v and 3 cell only show 2.3v and the charger can't continue charge it. May I know how can I charge the 3rd cell only to make it 3v then use lipo balance again? Can I charge the 3rd cell by using balance cable? I can measure which cable only 2.3v then I charge it from the balance cable by using Ni-Mh mode till 3v? Thanks.
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Old 02-11-2011, 05:10 AM
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What you say can be done exaclty as you have described it.
The pack is probably useless if one cell has been siting at below 3.0V for a long time but I see no harm in trying.
Before you do anything though check the cell voltages with a multimeter.
I recently thought I had a battery go bad only to find out that it was my voltage monitor.
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Old 02-11-2011, 07:15 AM
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Originally Posted by taz00 View Post
What you say can be done exaclty as you have described it.
The pack is probably useless if one cell has been siting at below 3.0V for a long time but I see no harm in trying.
Before you do anything though check the cell voltages with a multimeter.
I recently thought I had a battery go bad only to find out that it was my voltage monitor.
Hi, you mean I can use the balance point to charge up the 3rd cell and once it at 3v i can use back lipo mode to charge all 3 cells, right? I know that 3rd cell under 3v from my charger where it show all 3 cells voltage during lipo balance mode charge. Thanks.
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Old 02-11-2011, 07:40 AM
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What you will have to do is separate the 2 end plugs of the defective cell from the balance plug cable and connect them directly to your charger's output. It can be easily done with a sharp hobby knife or needle without damage.
You will have to charge at a low current since the balance cables are thin.
But before you do any of this make sure that your charger displays volts accurately.
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Old 02-11-2011, 07:47 AM
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Originally Posted by taz00 View Post
What you will have to do is separate the 2 end plugs of the defective cell from the balance plug cable and connect them directly to your charger's output. It can be easily done with a sharp hobby knife or needle without damage.
You will have to charge at a low current since the balance cables are thin.
But before you do any of this make sure that your charger displays volts accurately.
Hi, you mean remove the plug from the balance connector and as I know I need to remove the negative and 3rd cell positive cable then clip on my charger and start charge with low amp, right? Yes, the charger display is right. Thanks.
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Old 02-11-2011, 08:07 AM
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No, if you connect the negative and 3rd positive then you are connecting to the first cell's negative and 3rd cell's positive. Since the battery consists of cells in series you will see the whole battery's voltage.
What you need to do is connect to your charger's negative the 2nd cell's positive (which is connected to the 3rd cell's negative) and your charger's positive to the 3rd cell's positive.

In other words the last 2 cables from the battery's balance connector.
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Old 02-12-2011, 08:33 AM
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Originally Posted by taz00 View Post
No, if you connect the negative and 3rd positive then you are connecting to the first cell's negative and 3rd cell's positive. Since the battery consists of cells in series you will see the whole battery's voltage.
What you need to do is connect to your charger's negative the 2nd cell's positive (which is connected to the 3rd cell's negative) and your charger's positive to the 3rd cell's positive.

In other words the last 2 cables from the battery's balance connector.
Hi, I got what you mean and today I tried it and look's like my 3rd cell is die. It can charge by Ni-Mh till 1.5v then show full..... So do I need to modify the lipo if I want to use it as 2S? Can I just directly use 2S lipo balance mode to charge it without any mod on the cable? Thanks.
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Old 02-12-2011, 01:19 PM
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You have to modify the lipo to use it as 2s.
Honestly with the price of Lipos these days I don't think it is worth the hassle.
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Old 02-13-2011, 05:10 PM
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Originally Posted by taz00 View Post
You have to modify the lipo to use it as 2s.
Honestly with the price of Lipos these days I don't think it is worth the hassle.
Thanks for the advice.
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