The 8 level bar graph is for 2004-2007 Prius.
The 2001-2003 Prius has only 4 level bar graph, and it's control range seems the same, 40-80%.

Ken@Japan

Toyota's battery-charging algorithm is probably very complicated in order to correctly maintain its state of charge (SoC) inside their chosen range without suffering from any memory effect. Their patents on this are very detailed, and discuss many ways of monitoring and controlling it. ken1784's very interesting link shows that (at least for the Prius, and undoubtedly also for the TCH) the SoC display is decidedly nonlinear, in that fully 57% of the usable SoC is represented by bars #6 and 7 alone! No wonder the SoC display seems to spend most of its time in this range. This is probably also deliberate, so as not to alarm drivers by seeing the SoC continually going up and down. (This is rather like what they have done with the temperature gauge, which sits at the same reading for water temperatures from 60 to at least 90 degrees C.)

Stan

There is a promising new technology that should make all batteries obsolete.

http://www.sciencentral.com/articles...e_id=218392803

OMG, they stole my idea about using capacitors made from nanotubes I mentioned in msg#15, whom do I sue???

I read something about a place in Austin, Texas that converts the Prius to a plug-in. I'm not sure of the cost but they open the battery charge up. I'm not sure just how much. They also swap out the battery pack to a larger one. Reports of up to 125 mpg. After all a 10 amp charge running all night would not use that much electricity.

Stan,

Thanks for that clarification.

IMHO, it is easier to monitor the SOC of Li-ion than NiMH's.
So, my bet is the Li-ion will be used 30-90% range. We'll see sometime in 2010.

Ken@Japan