Fluke 540B - Rechargeable Battery Pack

3-33. RECHARGEABLE BATTERY PACK
3-34. The Model 540B Rechargeable Battery Pack
supplies a rechargeable + 12 . 5 volt de source, a re -
chargeable center tapped +12. 5 volt de source, and a
non-rechargeable +1. 35 volt de reference source for
the Model 540B Thermal Transfer Standards galvano-
meter system. The rechargeable batte:ry pack will
allow the instrument to operate for more than 100 hours
on a full charge. The single 1. 35 volt battery will last
for more than 2000 hours before replacement.
3-35. Refer to Detail I of the Model 540B Schematic
Diagram in conjunction with the following discussion.
Each of the rechargeable battery sections, BTl and
BT2, consist of ten nickel - cadmium batteries. The
non-rechargeable battery, BT3, is a mercury battery
used as the reference source for the Model 540B's gal-
vanometer system . The pilot lamp, DSl, indicates
when the power is applied to the unit for charging pur -
poses . AC voltage is applied to the unit through plug Pl
and coupled to the charging circuits through transformer
Tl. The full - wave rectifier bridges, CRl through CR4
and
CR5 through CR8, convert the ac voltages to de volt-
ages for charging their respective battery sections.
Supply voltage for the galvanometer protection circuitry
of the Model 540B is provided at pins 1 and 2. Supply
voltage
for the search amplifier and bias voltages for
the diode circuit arrangements in the Model 540B and
Model A54 are provided at pins 3, 4, and 6. Reference
voltage
source for the Model 540B galvanometer system
is provided at pins 5 and 7.
3-36. A few precautions should be observed when using
the Rechargeable Battery Pack. These precautions
are listed as follows:
a. Do not attempt accurate measurements while the
batteries are charging.
b. Full charge is obtained in 16 hours.
540B
c. Do not leave on charge for more than 72 hours.
d. Replace the mercury reference battery as required .
*Removed for NiCd bottery replacement
Figure 3-4. 5408
RECHARGABLE BATTERY PACK
3-5