6
ABSORPTION MODE
The converter normally provides a constant target output voltage of 13.6 volts (nominal) to power
ll the branch circuits. However, it is current limited, and if the output (load) current reaches its
maximum, the output voltage will drop as necessary to hold the converter’s maxi-mum output
current level (the amperage rating) without exceeding it.
BULK MODE
If the output current reaches its maximum (normally caused by a discharged battery), this will
cause the converter to go into Bulk Mode, which means the target output voltage will change to
14.4 volts and a timer will start. Although the converter is outputting 14.4 volts, you will not be
able to read that on a voltmeter due to the voltage-current relationship.
From the paragraph above, as load current increases, output voltage decreases. The actual
out-put voltage will not rise until the load current is reduced, which happens naturally as the
battery charges or if 12-volt appliances are turned off.
Bulk Mode will be maintained until the current draw drops to approximately five Amps, or until
the timer reaches four hours (whichever happens first). Then the target output voltage is changed
back to 13.6 volts for Absorption Mode. Lights that are powered from the output may change
brightness slightly at that time.
FLOAT MODE
The third mode of charging is what is called the “float” charge. This mode is designed to
provide a “trickle charge” to the battery after the system observes no significant variations in
current draw over a long period of time. When in “float” mode, the voltage will reduce from
13.6V to 13.2V and supply the “trickle charge” which helps to preserve the life of the battery
while keeping it charged and ready for use. A change in DC current will cause the converter to
exit the mode and return to the Absorption mode and then to Bulk mode if required.
NOTE: for a detailed explanation of the charging modes, please refer to our publication Theory
of Operation, document #AD-TD-0001-0.
Figure 2
