+
▬
24 VDC
195 GXL
12 VDC
▬
+
▬
195 GXL
12 VDC
+
195 GXL
12 VDC
▬
+
▬
195 GXL
12 VDC
+
A.4 Example
The following example shows how to calculate Peukert’s number and capacity from a configured battery string.
Consider four Alpha 195GXL batteries connected and configured as shown in the figure below. Two of the four
batteries are connected in series, and the two series strings are connected in parallel to the 24 V DC output.
Figure 58 — Battery string example
The Peukert’s number and capacity for the above configuration can be determined as follows:
1. Obtain the data sheet of the selected battery. See table below.
2. Find the current discharge ratings table in the data sheet. From the table, pick two current discharge values
(I1 and I2) that are closest to the calculated load current value. Look up the two discharge hours (R1 and
R2).
3. From the table, I1 = 15.2A, I2 = 12A, R1 = 6 hrs, R2 = 8 hrs.
From Equation (1) earlier:
Peukert’s number = n = Log (R
2
/R
1
)
(Log (I
1
) - Log (I
2
))
Log (8/6)
n=
= 1.217
Log (15.2) - Log (12)
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