Page 22 - i-MeIV Product Information

Lithium-ion battery

3-1-5 Balancing control among each cells
Each battery cell has area of over charging range and over discharging range, and it might be deteriorated quickly if the
battery cell voltage get into these area.
Therefore, BMU controls the battery cell voltage as neither over charge nor over discharge.
When charging DC 330V battery, BMU monitors the battery cell which has highest voltage, and control it as not to
enter over charge zone.
When discharging, BMU monitors the battery cell which has lowest voltage, and control it as not to enter to over
discharge zone.

However, differences among the each cell might be occurred as following graph , if the charging is repeated
many times.
BMU controls the charging and discharging according to the highest and lowest cells, used range of other cells become
narrowed.
This condition equals the battery capacity become lower.

To solve this condition, BMU send the signal to CMU in order to activates the balancing control if the following condi-
tions are met.
-Difference among each cells are exceeded while the normal charging.
-Difference among each cells are exceeded after Power switch “LOCK(OFF)”.

[Before activating the balancing control] [After activating the balancing control]

Over charge area

Area can be used Area can be used

Over discharge area

２１