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lipo charging question

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lipo charging question

Old 06-07-2021, 03:08 AM
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G'day all


I'm fairly new to this lipo battery charging deal and I'm having an issue with one particular battery.

It's an S3 11.1v 5000mha that has one cell that is causing the charger to time out. Cell 1 and 2 are at 4.20v but cell 3 was only getting to 3.90v.

After restarting the charger, cell 3 is now jumping between 4.01 and 4.02 and has been for more than 30 minutes.


Is the battery worth persisting with or is it now just a paperweight ?


Cheers.

Last edited by Wizstix; 06-07-2021 at 04:35 AM.
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Old 06-10-2021, 02:50 PM
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Probably have 2 issues. First, you probably over discharged this battery and cell 3's voltage dropped off much more than 1 and 2. A lipo's cells should be .05v or less between them at the start of a charge. The other explanation is that cell is toast (high internal resistance) which is causing it's voltage drop more than the other 2.

The second problem you're probably having is your charger doesn't have enough balance power. The charger puts in an amount of current, but then has to pull some or most of that off for the 2 cells that are full. You need to try and charge cell 3 individually back up to full. Some people have built a charge lead from a male servo connector that plugs into the balance lead. I just carefully use 2 paperclips stuck into the balance lead along with some alligator clip charge leads. Just make sure they don't touch and have no way of touching. Put tape or something on them to insulate them.

Here's a picture of various balance plugs. The colors on yours might be different, but the black wire will always the same. For the 3S connector, you need to connect the green wire to negative and the red to positive on your charger. Don't charge more than 2a as the balance wires can't handle a lot of current.

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Old 06-10-2021, 06:09 PM
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make 1 of these it will help charge only that low cell. helped me with a stubborn low cell of 10. you charge 1 cell on charge and fin what 2 balance wires have the low cell. one can charge a few amps unlike a balance charge or discharge...

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Old 06-11-2021, 12:48 PM
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i also have a up to 10amps charge thru balance plug only charge .. was gonna try to inject some humor wkhtg.
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Old 06-13-2021, 06:54 PM
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Thanks for the info guys, much appreciated. I forked out for a new balance charger and after roughly 5 hours or so at .5 of an amp the third cell made it's way to 4.20.
Seems ok now, though cell 3 does drop a little quicker than the others.
Guess i'll get just use it till it dies.

Cheers.
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Old 06-14-2021, 05:29 AM
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1/2 amp no wonder its taking you 5 hours..reset time limit to a great amount and use more than a 1/2 on that low cell.. that single cell lead i posted will take more than a 1/2 amp .
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