I just took delivery of my Prius last week and do not know if what I'm seeing is normal. Has anyone else seen this and is it normal? While at highway speed (60-75 mph) on level terrain - both with and without cruise control - I see the battery cycle between charge and discharge at a rate faster than 2 cycles per second. The display shows charging for a period of a few seconds and then enters a cycle of rapid charge/discharge for several seconds before settling back to several seconds in a charge state. When accelerating or going up/down hill this does not happen for the obvious reasons. I swear that I can feel the power fluctuations as well but that might be my imagination. I understand why the system would cycle, I'm just concerned that such a rapid frequency is a symptom of a problem.
I hope not.... I have noticed the same thing, though I can't remember feeling surges. I am a new Prius driver as well (<2 weeks). Avg 51 mpg so far.
Totally normal and exactly what the car should do. The Engine will run at a nearly constant RPM, that means sometimes it produces a little more energy than is being demanded and will show charge to the battery, when it needs a little more it take some from the battery...all part of maintaining maximum MPG. Those of us with instrumentation to watch know that those fluxes are very small, usually less than 6-12 amps either direction.
The video download from this webpage provides a sample of what we normally see... much like you described. .
Now, if you were seeing the number of bars on the state-of-charge display change by two bars per second, that would be bad.
