A123 Capacity et Energy vs differents charge currents graphs

I seen often people wondering about high current rate for charging LiFe cells like the A123 and i decided to test that to see whay it REALLY happen if you charge higher than 1C.

Tests conditions:

tool: Charger MegaPower 960-SR

-Capacity measurement

-Energy measurment (with logview software)

-Internal resistor measurment

-Temperature monitoring

- Graph view



Parameter:
Ambient temp: 21.5 degrees C

Charge current: Variable

Charge voltage: to 3.7V CC-CV

End Charge current 0.05A

Discharge current: Always 5.0A

Discharge minimum volt: 2.5V

Delay between charge and discharge: 10min


We can see that when we change the charge current by a factor 10 the total energy that the cell will give only decrease by 5%

Also, the energy lost during high rate charge like 10A represent 13%
and the energy lost at 2.3A decrease to 7%
In other words, the charge efficiency is 92% at 2.3A (1C) and decrease to 87% at 10A (4.34C)

This small difference should influence us to choose a high rate charger and stoping to border with capacity or energy lost... let's say that your A123 cells give you 800 good cycle before your ebike life end...

Here are my results on a good A123 cell: