Electro-Labs has posted a new project about making a programmable lithium battery charger shield for Arduino. The shield schematic and printed circuit board are designed using the SoloPCB tools, a Windows-based PCB designing tool from FabStream. The charger shield consists of a Nokia 5110 LCD and four tact switches for user interface, which allows users to program the charging voltage and current. Their design also features the ability to monitor the battery status before and during charge.
The circuit is based on LT1510 Constant Current/Constant Voltage Battery charger IC from Linear Technology. LT1510 uses the PCB ground plane as heat sink during operation. The four tact switches allows user to navigate through various features, which include setting the battery cut-off voltage and the maximum charge current, check the battery status, start and stop charging, etc. The charger stores the last set charging thresholds into Arduino’s internal EEPROM, so that at next startup the user don’t have to enter these values again. This lithium battery charger uses Arduino analog input pins A0 and A1 to sense the battery voltage and the charge current, respectively.