Cell Balance of New LiFePO Pack

[jurnaza]

So I just picked up my first LiFePO 2s pack and ran a couple cycles through it. On the initial charge towards the end of the charge the two cells got further and further out of balance til I ended up stopping the charge. I then decided to cycle the pack and see if it had the same issue and again towards the end of the charge the two cells got out of balance, but I let it go this time and it eventually finished but the pack spent half of the charge time balancing.

Is this normal for a LiFePO pack?

[wlfk]

My experience is that balance chargers can actually unbalance A123 packs because the charge/discharge curve is so flat until the charge level is very low or very high.

During the main part of charging, it's impossible to tell which cells are out of balance based on voltage, so some balancers will discharge cells, effectively at random.

It's better to only use the balancer when charging is nearly complete, or to balance infrequently at a very low charge rate (i.e. only very slightly higher than the maximum balance current.