Hi,

Since the floating voltage is not higher you can use an instrumentation amp to amplify the signal then have some sort of integrator circuit. Have a sign indicator / inverter to tackle charge discharge. A good option is to use an AD625 programmable gain intrumentation amp package. Then do the AD as normal. I use this in my industrial battery charger design and cannot give you code and schematic as it is a commercial design.Good luck.


Regards

Sougata