Using MAX8934 LiIon battery charger can be designed a simple battery charger which monitors the battery temperature (TBATT) while charging, and automatically adjusts the fast-charge current and charge termination voltage as the battery temperature varies.
Using MAX8903A charger chip can be designed a very simple high efficiency charger circuit using few external electronic parts .
The output current limit can be set up to 2A while USB input current can be set to 100mA or 500mA.
When the device is connected to the external power the system will be switched automatic from battery to the external power .
Using an LM317 voltage regulator can be made very simple charger, very useful for charging lead acid batteries. Unlike NiCd batteries, they must be recharged by connecting to a constant voltage (proper size).