12v lead-acid battery charger for 15-36V photovoltaic cells

 UNDER DEVELOPMENT

 source:       https://github.com/rodan/solar-charger 
 author:       Petre Rodan <2b4eda@subdimension.ro>
 license:      GNU GPLv3
 toolchain used: msp430-elf-gcc (Mitto Systems Limited - msp430-gcc 9.2.0.50) 9.2.0 linux

Features:
 - an MSP430F5510 uC controls all aspects of charging a 12v Pb battery
 - programming either via spy-bi-wire or usb (untested)
 - logging capability to a uSd card
 - backup 3v Li cell for keeping the RTC up-to-date
 - analog readout of battery voltage, input voltage, charge current, thermistor temperature, internal temperature
 - possibility to stop the charge if a condition is met
 - 8 status leds for verbose blinkiness
 - very low quiescent current

rev1 - used a LandStar charge controller that got replaced in rev3 with a PB137ACV ic
rev3 - 3V Li cell acts as bakup power for the uC, an SDcard is provided for logging
rev4 - SDcard is removed, 3V Li cell replaced by a 3.7v lipo + charging circuitry