BATTERIES 6
en-39
The conditioning process can be monitored by checking
the specific gravity of the battery cells. After the battery
set has been recharged, spot check two or more battery
cells. A fully charged fully conditioned battery with an
electrolyte temperature of 80° F (27° C) has a gravity
reading of 1.280.
Once the battery set has completed 50 charge/discharge
cycles, Depth of Discharge (DOD) can be measured.
To determine the DOD, measure the battery pack voltage
after mowing for a period of two weeks. Average the
results and look up the DOD, using the left side chart in
Figure 6B. These values are based on a standard 78° F
(25.5° C) battery temperature. Using the DOD refer to the
right side chart in Figure 6B to determine theoretical life
cycles.
As a battery ages, it still performs adequately except the
expected run time, or capacity, will decrease. Capacity
describes the time that a battery can continue to provide
its design amperes from a full charge.
Temperature is important when conducting tests on a
battery and test results must be corrected to compensate
for temperature differences.
Figure 6A
Figure 6B
Age vs Capacity 80% DOD
0.0
20.0
40.0
60.0
80.0
100.0
120.0
0
50
100 150 200 250 300 350 400 450 500 550 600 650 700 750
Cycles
C
a
p
aci
ty
, %
@ 5
6
Am
p
s
<10% of Total Cycles
>80% of Total Cycles
0
10
20
30
40
50
60
70
80
90
100
0
500
1000
1500
2000
2500
3000
3500
4000
4500
5000
5500
6000
Theoretical Life Cycles
D
e
pth
of D
ischarge (%)
Depth of Discharge
DOD %
0
10
20
30
40
50
60
70
80
90
End of mowing
Voltage (V)
50.928
50.472
49.992
49.488
48.960
48.408
47.832
47.256
46.632
46.032
