— 11 —
Battery manufacturers normally specify maximum permitted depth of discharge values for their products.
Depth of discharge (DoD) is the percentage of capacity removed from the fully charged battery. DoD
is the inverse of state of charge (SoC + DoD = 100%).
Figure 2. Typical cycle life (the number charge/discharge cycles before battery's performance
has been significantly reduced) vs. Depth of Discharge
Discharging below the specified DoD limit would damage the battery and decrease its expected lifespan
(commonly expressed as state of health — SoH). The purpose of monitoring battery’s state of charge
is to keep it from discharging deeper than permitted, and thus extend its operational life.
10,05
10,5
10,95
11,4
11,85
12,3
12,75
0
500
1000
1500
2000
2500
0
20
40
60
80
100
120
Vo
ltag
e,
V
# o
f cy
cl
es
Depth of Discharge, %
Example of Depth of Discharge vs Cycle Life for 12V
Lead-Acid Battery
Summary of Contents for NMEA 2000 YDBM-01
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