The power source chosen was 2 series connected LiFePO4 18650 cells from A123 Systems with a cutoff voltage
from 2 V till 3.6 V and nominal voltage 3.3 V.
Moreover, the degree of capacity fading increases with the increase of charge cutoff voltage, in which is mainly due to gradual decaying of electroactive Co .
The cyclic voltammogram (CV) curves were obtained between the cutoff voltage ranges of 2.0~4.8 V on an IM6 electrochemical workstation at a scan rate of 0.1 mV/s.
It is worthy to note that the discharge capacity increases but leads to fast capacity fading with the increasing of cutoff voltage, especially for the bare material.
Obviously, doing this over and over takes a toll and ultimately as the cycles continued, some of the batteries started to fail the capacity test by reaching the cutoff voltage
before they were supposed to--in other words, the capacity dropped below the 80-percent level--at which point we stopped testing that battery.
With additional knowledge of the electrical current profile, along with temperature and cutoff voltage
, the required "capacity" of the battery can be calculated.
15 and 16 demonstrate a narrowing of the conical top envelope associated with increased cutoff voltage
, which has its experimental counterpart in experimental behavior under increased pressure.
So, in the actual use of the cell, the cutoff voltage is set to be below 4 V.
5 [micro]A/[cm.sup.2], and the cutoff voltage was from 2.0 to 4.2 V.
The dedicated tester is a push-button, walkaway design with the capacity percentage displayed after the tester automatically shuts down at the proper cutoff voltage.
The Black and Decker j multi-stage charger has a cutoff voltage that's too high (15.2 volts) and a float that's also too high, at 13,5 volts.
With the VDC Battery Minder, on the other hand, we would like to see a higher charge cutoff voltage
for optimal charging and a lower voltage trickle mode for long battery life.