Same anon than >>5081
. On a second note I get it, it's actually better to have thread about real batteries, power sources and technical details of these, while this here is more of a speculative and broader discussion.
Your thinking is of the rails nevertheless, IMO. Two kilowatts for a onboard computer is absurd and I also don't see how to get to 500W usage at the same time for the mechanical parts.
Additional to the onboard computers, there will be external brains, wifi connected home servers. But they'll rater use max 500-700 Watts. How much more might depend on how much one is willing to spend.
Also if more advanced waifus need a lot of mechanical energy we'll need to use airmuscles and at least one onboard tank. Also, they don't need a huge range, from one room to another is sufficient for most people. They can plugin for some time while sitting and talking, and cuddling on the couch won't need much energy.
We might simple have different levels of development in mind. The most simple Robowaifus won't need a lot of energy, if you speculate about very active, smart and mobile ones, it might be more about future technologies. But then computers, batteries and motors might also be more efficient.
Direct ethanol fuel cell is my current idea of a source for a longer range.