[frenchie]

Does anyone know how much energy can the battery store in the new Prius, and if there is any improvement compared to the current model ?

 

[clett]

Not sure about energy density or total charge capacity for the 2004 Prius battery, but Toyota are keen to point out that the power density is much improved.

There's a graph here of how much it is improved over the first and second generation earlier Prius batteries - but no figures unfortunately!

8)

 

[john1701a]

http://john1701a.com/prius/prius-presentations04.htm

Page 33 of the 2004 Tech Presentation states the increase is 35%

Page 34 shows a graph of the 3 generations of battery-pack showing mass & power improvements.

 

[frenchie]

There's a 35% increase in *specific* power, that is in power per unit mass, not in power. The same presentation tells the power is the same (21 kW).

Actually it appears that there is less energy stored in the new battery, since the modules have the same energy storage capacity and their number is reduced from 38 to 28. That makes a 28% decrease, but we have also to take into account the state of charge range allowed by the hybrid system control (as you know not all the electricity stored can be used, for battery life purposes). Has anyone any idea about this ?

 

[clett]

I guess Toyota have learnt from customer feedback from the first generation Prius that hardly anyone complained about the 'turtle light' coming on too often. They probably therefore feel that Prius 1 was a little over-engineered in terms of outright battery capacity and are more confident that they can make the pack smaller (and hence cheaper) for the 2004 Prius.

If the battery is one third cheaper but provides as much functionality as required for the vast majority of owners - they could be well on the way to making the 2004 Prius profitable from the outset. :wink:

 

[frenchie]

Self-answer to my own question :

I 've just read on the 2004-prius yahoo group that someone has been able to discuss with Dave Hermance, Toyota chief engineer, about the 2004 Prius at Michelin Bibendum Challenge. He said that although the total amount of energy was lower in the 2004 battery, the available energy is about the same because Toyota engineers learned from the current generation that they could use a greater charge range (the cells used are a newer generation too). Therefore, with a smaller, lighter, less expensive battery but which stores (in practice) the same energy amount and delivers the same power, the new Prius achieves higher performance and efficiency levels due to many improvements (body shape, engine and motor efficiencies, electronic control...).
Cool... 8)