Teledyne PEM-9004 - Portable emissions analyzer - Manual (Page 28)

Installation PEM-9004
Teledyne Analytical Instruments 16
when charging. If a NiCad battery is always charged from 80% to 100%
i.e. the state of discharge of the battery never falls below 80% before the
battery is recharged, the battery will lose some of its capacity. This is
called “memory effect” and is a well-know problem in rechargeable
batteries. The battery remembers to what extent it is run down.
A part of this memory effect is suppressed by the load management
unit. It senses the state of discharge of the battery and will not allow
recharging until battery capacity has dropped below 60%.
Constant overcharging has adverse effects on the NiCad battery as
well. The load management feature monitors the state of charge, the
voltage, and the battery temperature. When predefined limits are
exceeded, the charging process is interrupted. After the appropriate
parameters are restored, the charging process is automatically restarted.
The service life of the NiCad battery can be significantly reduced
when the instrument is operated at temperatures below 40°F (5°C).
The graphic charge level indicator on the front panel display is
comprised of 10 battery symbols and is located in the one-line status
display during the calibration phase. The PEM-9004 load management
unit continuously monitors the incoming and outgoing current during
operation and charging. Under normal operating conditions, the
instrument should be operated until the battery is completely run down
(10 empty battery icons as opposed to dark, filled icons). When this is
routinely followed, the actual capacity of the NiCad battery is accurately
shown on the display.
3.4.2 Battery Replacement
Contact factory for battery replacement
3.5 Sensor Replacement
Up to 5 electrochemical cells are installed in the PEM-9004 analyzer
depending on the options ordered. When new cells are ordered, they are
packaged in a controlled atmosphere. The instrument is shipped with the
required sensor cells installed.