Relationship of Regenerative Braking Intensity VS. Efficiency - What is best?

Then his explanation about overcharging is pointless if it will never occur.

 

That is for a full charge cycle. Within the cycle, incremental efficiency varies, and gets lower as the battery approaches full. The Prius never ever uses that whole range, never gets close to truly topped off. Withing the portion of the capacity range actually used, charging efficiency should be better.

Of course, this is just for the battery. The motor/generators and inverter and mechanical drivetrain each take their own cut, twice (once in each direction), so the round trip compounded efficiency loss is high.