Hach 900 MAX - Manual (Page 106)

Page 104
Memory Battery
8990mnt.fm
Section 7
7.11 Memory Battery
Random Access Memory (RAM) is a very reliable data storage medium for
microprocessor applications. However, RAM requires power at all times. If
power is removed, the data stored in the RAM chip is lost. Therefore, RAM
chips cannot be powered from the sampler power supply because data and
program settings would be lost every time the power cord was unplugged. A
separate battery located inside the sampler controller is provided to power the
RAM chips and the real-time clock. The memory battery keeps the program
entries and logged sample data alive inside the RAM memory when the main
power fails or is removed for transport or replacement.
The sampler memory battery consists of two “C” cell alkaline batteries.
Should the memory battery voltage fall too low to properly maintain the
program settings, a warning:
MEMORY POWER LOW will alert to replace the
battery. The sampler utilizes a very small amount of energy from the memory
battery during normal operation. The service life of the batteries in this
application is typically five years.