Lipo charging help please.

[Andy-E]

When charging my 3s 3000mah lipo from dead one cell is going to 4.2v and the other 2 are still at around 3.9 and the charging amp drops to 1.0a and takes forever to charge. What';s going on with it? It seems a good battery with no swelling. Any help would be appreciated, cheers.

[Revs]

When charging, once one of the cells reaches 4.2v, the charger stops charging through the main power leads and starts charging the remaining cells through the balance leads, which can';t carry the same current. Normally the cells aren';t too far out from each other voltage wise, so it doesn';t take long. But if you over-discharge the battery, more often than not, some cells will be discharged a lot more than others and therefore it takes longer to balance them.

You';ll just have to leave it balancing for as long as it takes and it can take ages if one or more cells is over-discharged.

What were the cell voltages before you started the charge?

[Andy-E]

When charging, once one of the cells reaches 4.2v, the charger stops charging through the main power leads and starts charging the remaining cells through the balance leads, which can';t carry the same current. Normally the cells aren';t too far out from each other voltage wise, so it doesn';t take long. But if you over-discharge the battery, more often than not, some cells will be discharged a lot more than others and therefore it takes longer to balance them.

You';ll just have to leave it balancing for as long as it takes and it can take ages if one or more cells is over-discharged.

What were the cell voltages before you started the charge?
Oh right thanks. That makes sense. Voltage before I cherged was around 11.2v if I remember right. Not sure on the v per cell as I didn';t look.

[guest325]

If you over discharge your batteries they won';t last very long, get yourself a cheap battery checker and don';t discharge them down to less than 25%, preferably 30% as said previously over discharge causes imbalance and sometimes catastrophic failure (magic smoke / fire) be warned!!!

[bobit200]

if you can measure the internal resistance of the cells.  I had a battery that took ages to charge with a mismatch in voltages.  When measuring the resistance the cell in question had a much higher resistance than the other cells.  If so, best be on the safe side and retire the pack to desk duties.