Lipo not balancing

[deano261]

I recently recovered a lipo from a low voltage and now the lipo won't balance correctly because when I look at the voltages they aren't even close (the first cell is the one that is lower the second cell is charging fine)

[Steven Forster]

Originally Posted by deano261

I recently recovered a lipo from a low voltage and now the lipo won't balance correctly because when I look at the voltages they aren't even close (the first cell is the one that is lower the second cell is charging fine)

stick or saddle pack ???

[deano261]

its a stick

[_sleigh_]

You'll probably find that an individual cell is buggered. You need to remember that the packs we run are made up using 3.7v cells (normally 4 cells in total in a combination of parallel and serial configuration)

[leeleefocus]

The cell you say that is charging fine is actually the one that is buggered.

What has happened is the cell has developed high Ri and probably reduced capacity.

Because of the high Ri it reaches 4.2v first and then the charger has to try and bleed off current from this cell so the other cell/cells can catch up. Most chargers that we use can only bleed of 300ma max from individual cells. In your case the difference between the cells now is to big for the charger to be able to balance.

If you applied a load to the battery the cell that reaches 4.2v first during charging will actually be the cell that sags the most during discharge. It's all to do with the Ri of the cells.

Like what Sliegh said you've got a buggered cell. It's bye bye battery i'm affraid with this big of a difference in the cells.