User's Manual

Chapter 4 Battery Care and Replacement
48 CCU 100 and Repeater 100 Installation Guide
Proprietary and Confidential
Battery Storage and Charging
To ensure maximum lifespan and efficiency from your CCU/Repeater batteries, Itron
recommends the following storage and maintenance procedures.
Long-Term Storage
Batteries may be stored for up to two years at room temperature (25°C or 77°F), and then
may be recharged with no loss in cell reliability or performance capabilities. The example
storage time versus temperature chart below is a plot of maximum storage time as a
function of storage temperature. This curve shows the maximum number of days at any
given temperature, from 10°C (50°F) to 65°C (149°F), for the battery to discharge from a
fully charged state of about 6.42 volts (2.14 volts per cell) down to a zero charge state of
5.79 volts or (1.93 volts per cell). The battery should not be allowed to discharge below
5.79 volts because of the danger of damaging the performance characteristics of the
battery permanently.
When batteries are stored at or near 25°C (77°F) it is recommend to conduct an open
circuit voltage (OCV) audit every six months and recharge when OCV readings approach
6 volts (2.00 volts per cell). If storage temperatures are significantly higher than 25°C
(77°F), even for short durations, the frequency of OCV audits must increase.
It is important to recognize that the self-discharge rate of the battery is non-linear. The
rate of self-discharge changes as the state of charge (SOC) of the battery changes. The
time taken for a battery to discharge from a 100% SOC to 90% SOC is different from the
time it takes to self-discharge from a 20% SOC to a 10% SOC.