LiFePO4 won't charge over 3.3v per cell

[KrisThompson]

If the cells have never been top balanced, you could be waiting almost forever for your charger to balance them out at a measly 0.3A. You are probably better off disassembling the battery and reconfiguring the bus bars so all the cells are in parallel, then putting your charger back on and charging them as a 1S single cell up to 3.6V.

After that, with them all at the same state of charge, they can go back into their 4S configuration and future charges will only need a very brief balancing stage at the end.

Thanks, it's really strange because during balance charging at one point they were all the same voltage. It wasn't until one got to 3.6 and the charge current dropped, the voltages dropped a bit.

It seems like they display higher voltages when the charge current is high.

Another thing is happening that I don't understand - when I charge 1 individual cell, the voltage shoots up to 3.6v instantly and the charge current drops to 0.5 amps. I can't get it to go any higher. I think this is something to do with the hobby charger because my other hobby charger does the exact same thing

 

[mikefitz]

Bleed charge from the high cell whilst under charge and monitoring cell voltage. Use a DC load, a 12v car headlamp bulb is suitable. Apply across the high cell for a few seconds. With a little practice it's possible to get the cells within a few tens of mV.
If changes are occurring too quickly reduce thecharge volts/current.
If you refer to the graph I posted earlier, you can see the voltage rises very quickly as the cell becomes full, at this point the current will fall to a low value ( with voltage limited charger). It only needs a small difference in cell Ah for the lowest capacity cell to reach 'full' before the others. What you are seeing is normal.
Under every day use charge to 14.0 volts ( 3.50 volts per cell) with short absorbtion period.

Mike