User guide

Battery Life
The NiMH battery will last longer and perform better if allowed to completely discharge
before recharging. For maximum battery life, it is recommended that the NiMH battery be
completely discharged and recharged once every three months.
The charging circuitry inside the Site Master is designed to optimize the life of the battery.
If the temperature inside the instrument exceeds 50°C, the current charge cycle will be sus-
pended and a new charge cycle will not start until the temperature has come down to 50°C.
The Site Master is also equipped with an automatic charging process that changes the
charging level based on the battery capacity. If the battery has been completely discharged
to zero volts, a pre-charge at a low DC current will be applied until the battery reaches a
level which is safe for a faster charge cycle. Similarly, the charging level will change when
the battery is close to fully charged. This charging process helps maximize the number of
recharge cycles available from the battery.
It is normal for NiMH batteries to self-discharge during storage (Figure 2-9) and to degrade
to 80% of original capacity after 12 months of continuous use.
The battery can be charged and discharged 300 to 500 times, but it will eventually wear out.
The battery may need to be replaced when the operating time between charging is notice-
ably shorter than normal.
Chapter 2 Functions and Operations
2-25
Figure 2-9. NiMH Battery Storage Characteristics