The MM104 mini module from Velleman is a
Li-ion battery charger breakout board that incorporates the charger for
a single 3.7 volt (4.2 V at full charge) Li-ion element; it is based on
the MCP73831T integrated circuit. The card accepts typically a 5V input
voltage that can come from a common power supply, from a compact
photovoltaic panel or even from a computer USB port. On SOL output
contacts it is present a 4.5 to 6 volts voltage, providing the right
potential and current required to charge both Li-ion and Lipolymer
elements. The battery (to be connected to the +/- BAT contacts) can have
a theoretic unlimited capacity, since the limitation depends only by the
charging time (that could be really long for high capacity batteries).
However, considering that for example a 550 mA current charges a 550 mAh
element in one hour, a 1,100 mAh will take 2 hours, a 5.5 Ah will take
10 hours and so on. In the breakout board, the integrated circuit works
in the typical configuration that sees the light emitting diode LD1 fed
(by the resistance R2 that limits the current) from the STAT output. |