Trying to determine dc current - 12v lead acid battery charger

[tasmod]

I originally blindly built this unit before realising only the hex was available at the time. I've since changed computers a few times and the code was lost.

Now it's a project for me as I'm experimenting (playing ) with car batteries. I want to go on and design a versatile charger with data storage for downloading charge discharge/curves along with control of a desulphator unit. I've a couple of 24LC16b chips which I can I2C for storage, along with a Max232 for PC connection.

I've managed to recover one battery that had sulphated after being left for a month during Feb when temps were below freezing. Normally indoors and float charged necessity meant it was left out connected to a non used vehicle. The battery was only a year old and current replacement costs meant I wasn't going to let it die without a fight.