Each of the 16 modules is split into 6 blocks where the 70+ cells within a block are all wired in parallel -- so they are going to have the same voltage. The blocks within a module are wired serially and the modules are also wired serially.

Each module has a battery monitoring chip:

http://www.ti.com/product/bq76pl536a

It has seven voltage measurement inputs (between each block and before/after the outer blocks) so it can tell the voltage of each block. It can also control a bleed resistor per block (for balancing). There are two temperature sensors per module.

Each module also has an 8051 (C8051F530A) that talks to the battery monitoring chip and to the data network connecting the modules to the "global" battery management system which has a Altera CPLD and (probably) an ARM CPU.

http://www.teslamotorsclub.com/showthread.php/34934-Pics-Inf...