There is a firmware for a PIC 16F737 and a small VB application that can be used to log voltage measurements over the life of the batteries. The 16F737 should be connected to a PC serial port with a MAX203. Every 60 seconds the supply voltage, output voltage, and reference voltage can be logged to the PC. A nice graph can be made showing each voltage through the charge time. This was never used because the charger is was never functional. Everything is verified to work. The test firmware, and a small visual basic program to log the output, are included in the project archive. I'll leave the wiring to you.