49
Table 11 – Charge current and voltage calculation examples
Example 1
If a cell group has 3 cells in parallel (3p), and the recommended charge
current per cell is 20A, then the charge current for this group is
60A: (3 cells, parallel) x 20A = 60A
Example 2
If a cell string has 10 cells in series (10s), and the recommended charge
voltage per cell is 3.6V, then the end of charge voltage for the string is
36V: (10 cells, series) x 3.6V = 36V
Once the end of charge voltage has been reached, apply a constant voltage hold at this voltage until the current
decays to near-zero. This process charges the cells to 100% state of charge (SOC). Refer to Figure 25
for an
illustration.
Figure 25 – Battery voltage and current during recharge
Recommended Fast Charge Method for Strings
The cells can be charged at a fast rate if a short recharge time is desired by the application. Faster recharge rates
will reduce the cycle life of the battery by:
•
Increasing the internal wear and tear on the cell electrodes which reduces its capacity faster than normal
•
Increasing the internal temperatures in the cells, which increases degradation rates of the cell’s capacity
and impedance over time.
Figure 26 shows that a cell that is regularly recharged at a fast rate will suffer an accelerated rate of capacity
degradation over its service life.
