When you connect 2 9000 mAh cells in series, the resulting battery has 2x the voltage but the same mAh capacity. In parallel, the battery has the same voltage but 2x the mAh.
> My expectation on timescale is that genuinely general-purpose robots will need at least as much compute as a self-driving car (possibly more, that's a minimum), and have at most 1/10th the available power to do that (because they're physically smaller).
This seems logically flawed:
1. A car travels hundreds of miles from home. Why would a robot walk more than a while from a transport or home base? At short distances, if you truly need that power, it probably makes more sense to stream data/video over a direct low-latency connection. Long distance networking has a latency comparable to camera frame time, but even a normal wifi router can keep a lower latency than human nerve delay.
2. Humanoid robots will never be running at 85 mph past a bunch of people. They probably don't need to have the same compute throughput as a car, and definitely don't need to have the same reaction time.