ITech IT6700 Series User Manual page 10

Battery charging protection
Pay attention to the positive and negative terminals when connecting the
battery. If the battery is connected reversely to the power supply, it will
result in damage to the power supply.
When using the power supply to charge the battery, a diode and a fuse must be
connected in series with the output as shown in the following figure to protect the
circuit . The detailed methodology is shown as follows.
The role of the diode and the fuse in the above figure is described as below.
 The role of the diode is to block any reverse voltage and current flow to the
battery to protect the power supply and prevent the internal parts from damage.
The series diode can also avoid the condition that the battery discharges due
to the internal resistive load of the power supply in the power-off or output-off
state.
When selecting the diode, the user should consider the following notes.
The current capacity of the diode should be 110% of the rating current of the
battery at least. When setting the input voltage of the battery, the user need to
consider the threshold voltage of the diode. The typical threshold voltage of a
silicon diode is 0.6 V to 0.7 V. The reverse breakdown voltage of the diode
should be more than twice the rating voltage of the battery. The user also need
to consider the power of the diode and add a heat sink when necessary
 The role of the fuse is to interrupt the current by melting the metal wire in it
when the current rises to a certain value, thereby protecting the circuit.
When selecting the fuse, the user should consider the following notes. The
rating current of the fuse should be 150% to 200% of the maximum current of
the battery and be less than 150% of the maximum output current of the power
supply.