Chapter
3
Formulas for Hot-Swapping
One battery module can accommodate up to 63 A. If the amount of current that each
of the remaining modules has to accommodate exceeds 63 A, hot-swapping is not
allowed. The following formula calculates the maximum current per module that
allows hot-swapping.
The maximum current that allows hot-swapping
= the higher-level system’s current ÷ (the number of modules installed − the
number of faulty modules that should be replaced)
For example, if two modules are faulty and the higher-level system’s current is 120 A
when six modules are installed, the maximum current during hot-swapping is 30 A.
120 A ÷ (6 - 2)
= 30 A
Use the following formula to determine how many faulty modules can be replaced
at a time.
The number of hot-swappable modules
= the number of modules installed − (the higher-level system’s current ÷ 63 A)
All the decimal places should be removed from the result without rounding. For
example, if two modules are installed and the higher-level system’s current is 70 A,
no modules can be replaced.
2 − (70 A ÷ 63 A)
= 0.89 = 0
If four modules are installed and the higher-level system’s current is 80 A, two faulty
modules can be replaced at a time.
4 − (80 A ÷ 63 A)
= 2.73 = 2
Use the following tables for quick reference when hot-swapping faulty battery mod-
ules.
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