User's Manual

Chapter 4 Battery Care and Maintenance
54 TDC-0971-011 CCU 100 and Repeater 100 Installation Guide
Proprietary and Confidential
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
following storage time versus temperature chart 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). Do not allow the battery to discharge below 5.79 volts.
A battery discharge below 5.79 volts may permanently damage the performance
characteristics of the battery.
Itron recommends you conduct open circuit voltage audits every six months on batteries
stored at or near 25°C (77°F). Recharge batteries when OCV readings approach 6 volts
(2.00 volts per cell). Increase OCV audits if storage temperatures are significantly higher
than 25°C (77°F)—even for short durations.
It is important to recognize the self-discharge rate of the battery is non-linear. The rate of
self-discharge changes as the battery's state of charge (SOC) 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.