Hey Dave,
I think I can add some information about the HUGE capacitors you found inside the UPS... I have been involved in motor controllers for combat robot in the past years, and motor controllers and UPS usually look much very alike (Battery + H-Bridge + Inductive Load).
What happens is, when there is a power failure and the battery switches on, the load at which the unit is connected might need a huge power burst, and batteries are usually horrible for delivering high amounts of current in a short time (this is measured by the batteries C rate), and capacitors are very good at it...
...BUT the real problem in high power applications is the stray inductance of the connections, wire, PCBs etc.. since there is a H-Bridge switching the battery's voltage, the turn-on and turn-off time of the MOSFETs are really short, dealing with high ammounts of current at the same time... this will cause high voltage spikes in the battery that can really damage it AND completely destroy the MOSFETs. The capacitors are there to smooth and absorb the voltage spikes in the MOSFETs and in the battery, preventing a total destruction of the system due to the inductive load of the transformer.
(begginers, remeber, V = L di/dt, so high current being switched at low time will generate a really high voltage spike! And most MOSFETs in the market wont survive this spikes)
As to the battery charging patent, this is very much the same as vehicles use as "regenerative braking", where the vehicle uses its own movement, due to inertia or some external force, like descending a hill, to charge the batteries using the internal diodes of the MOSFETs (usually there are dedicated schottky diodes as well, since this MOSFET diodes have high voltage drops in the order of 1.5V and heat a lot the MOSFET).
After years learning in the EEVBlog, It feels great to be able to contribute a bit too