The current sensing portion of the project is on hold for the moment while I await delivery of a Hall effect device from Spark Fun. It's their breakout board with an Allegro ACS712-5A surface mounted to a PCB with wide traces for a decent amount of current.

At any rate, I worked on the voltage sensor portion of the project. The breadboard contains a voltage divider: R1=20k, R2=10, and a 10k trim pot. That scales the voltage from the charger down to less than 5 volts. In software, the Arduino prints out the current voltage to the serial port. On my MacBook, I'm capturing the data using a retro application called SynchTERM. It gave me some 80x25 ANSI color, 2400 baud BBS flashbacks. I massage the data and imported to Numbers. The graph shows when I first connected the batter to the charger -- it waited for a bit to see about the condition of the battery. Then it pushed 2 amps at roughly 14.6 volts into the AGM VRLA battery. I'm not sure what criteria the BatteryMINDer uses to drop down to the lower voltage trickle charge. I would like to figure that out, so I can mimic the charging profile.