I'm playing with my hyperion and tried a charge discharge test to see how my lipo zippy 20S8AH is performing after 40 cycles. And if I shall invest in A123 or keep my lipo (depends on the capacity loss).
It seems to be very balanced when I'm charging/discharging from 4V to 3.75V. But over that I've one cell that peak a lot over 4V:
This is the charging graph until 4.12V. I didn't go over to preserve the battery life. But when I go over the gap from the red cell is higher and higher.
What's strange is that during discharge, the cell quickly align with other cells:
During discharge the cells gap become minimal (around 0.014 mA gap), and capacity between my 4 * 5S8AH zippy pack are similar.
I've done something like 10 cycles of charges/discharge without balance if I keep my cells between 3.75V and 4V and they'll remain greatly balanced. All bulk charge no hassle!
Under 3.65V, I have the red cell that's falling down like crazy:
The other pack performs better, but it's still a cliff under 3.65V:
However I'm still a bit concerned. Is it a weak cell that may fry over time?
- Replace the cell
- Or add an additional pack on top to compensate this cell
- Or maybe it's normal and I don't need to do anything?
ps: I have around 6AH available on discharge between 4.07V and 3.65V. Not sure if it's good for a pack.