yes, mantruck101, thanks so much for that video! It is very, very interesting and informative. I hope we can somehow keep it accessible through this site for a long, long time.
billyK, you've hit the nail on the head regarding the primary hurdles to altering/upgrading any battery in vehicles like this; "programming". I would expect a change to any Li battery to be quite complex, as their charge, discharge, heating, cell impedance, cell failure mode, voltage, life expectancy, storage, operating temperature, and packaging characteristics are much different than any existing NiMH or NiCd battery. An updated NiMH cell change could be made to existing NiMH packs relatively simply if not for the battery charge / discharge / idle program. No benefits could be realized from any other cell type without a control program specifically tuned to take best advantage of those specific cell characteristics.
If the vehicle were in effect controlled by an industrial PLC, I'd tear into the project right now, but auto makers chose from the onset of their use of microprocessor based controls to decentralize controls, and go as proprietary as possible with any and all components. I hate the proprietary bit at some levels, but can accept it if "manufacturers" options and upgrades are available. I'm an auto consumer created by automakers; I want options. I'd like to be able to choose my battery characteristic. I'm also unwilling to treat a car like the cell phone makers are forcing us to treat their products: if the battery's getting lame it's time for a whole new phone or car.
Why not offer different hybrid options? A hilly option, a hot weather option, a snowy climate option, a big city or taxicab option, a long-life option, a heavy mileage option, and of course the big-bucks PHEV option. I think that the market is mature enough to support it now, and I don't feel it was 5 years ago. I do feel that the battery pack form factor, package, system electrical characteristics, as well as ventilation requirements and connections on the 2008 Escape HEV battery are suitable for a variety of other Ford and non-Ford vehicles. I've got a feeling though that HEV batteries will be like cell phones though, and we'll all just shrug our shoulders and go along with it.