Service manual

5.2.5 Standard Charger and Super Charger
The utility of charger is to recharge and to maintain the batteries at fully charged condition.
The charger the battery with a constant current at initial stage, as the battery voltage keep
increasing, the charge current decrease accordingly, and the voltage until the floating recharge
voltage, and the charger will control the output at a constant level (2k/3k 110.4 Vdc, 1k
41.2Vdc). In this way, to make the battery full recharged but not over recharge, protects and
prolongs the lifetime of charged batteries.
Refer to fig. 5.2.5.1; the battery charger employed a Flyback topology, under controlling of
the controller mainly comprise an ASIC uc3845, the switching component MosFET turn on /off
at a frequency around 100KHz, when the MOSFET is turn on, the current in the transformer
increase, and a certain amount of energy is stored in the transformer, when the MOSFET turn
off, the energy stored in the transformer start to release to from the secondary side of the
transformer and charge the output capacitor, by controlling the duty cycle, energy transfer to
secondary side of the Flyback circuit can be controlled, and so on the output voltage.
Fig. 5.2.5.1 Topology of the standards and supper charger
There are two kind of charger for standard model UPS and long backup time model UPS.
Both operating in the same principle, but difference output capacity, the one for standard model
UPS capable of outputting 1A current, is soldered on the PSDR, Fig. 5.2.5.2 shows photo of
standard charger. A super charger module with maximum 8A charge current capacity, is used
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