2011 Sienna Hybrid to get Lithium from Sanyo

[bwilson4web]

Originally Posted by clett

The answers you seek can be found by comparing figure 1 (NiMH) with figure 3 (LiIon) in this paper:

http://umanitoba.ca/outreach/confere...wed_Valoen.pdf

This is at very low rate (C/10), the losses would be much higher at higher rate, as used in the HEV scenario.

Nice paper including this:

. . .
There will be some voltage threshold for all battery chemistries beyond which this electrolyte decomposition starts to happen. However, there is a fundamental difference between NiCD/NiMH and Li-ion since this electrolyte decomposition is mostly reversible for the former, whereas for the latter electrolyte decomposition is irreversible (Besenhard, 1998).
. . .

I had read somewhere that Li-ion batteries tend to have a finite life and now I have a source. I know that loss of water from NiMH appears to be the aging mechanism for NiMH cells and this can be replenished. But it looks as if Li-ion definitely have a built-in failure mechanism.

Bob Wilson

[clett]

It depends on the chemistry. There is a huge variety of lithium-ion chemistries available today, many much more advanced than the cobalt-oxide based varieties people are familiar with in their laptops and cameras. The titanate batteries, for example, have exceptionally long calender life and cycle life, even under harsh conditions.

[bwilson4web]

Perhaps we need to study the charge-discharge efficiencies of each chemistry versus a blanket statement? Not trying to be difficult but having found that not all 'standard parts' are interchangable . . . <grins>

Bob Wilson

[ken1784]

Originally Posted by drees

Do you have up-to-date NiMH charging efficiency data?

I saw it once from Toyota's internal document, but it is not shown in public.

Originally Posted by clett

The answers you seek can be found by comparing figure 1 (NiMH) with figure 3 (LiIon) in this paper:

http://umanitoba.ca/outreach/confere...wed_Valoen.pdf

They use unnamed 19.2V 2.6Ah NiMH power tool pack for the experiment.
The specifications are completely different between power tool pack and vehicle applications.

Ken@Japan

[spwolf]

Originally Posted by Mike Dimmick

Panasonic EV Energy is 60% owned by Toyota, 40% by Matsushita, Panasonic's parent company. They're not going to starve their own child.

Toyota need a deal with the new owners of the NiMH patent, Samsung and Bosch's joint venture SB LiMotive, to allow larger NiMH batteries to be used in full EVs and plug-ins. My recollection is that some analysis has been done on how much capacity the battery needs in a charge-sustaining hybrid, which indicates that there are diminishing returns as you increase the capacity (hence size and weight) of the battery. Prius won't benefit much from a larger battery, unless converted to a charge-depleting, plug-in vehicle.

Li-Ion has an aging problem. The chemistry deteriorates with age, not just cycles. It also deteriorates more with higher discharge rates. Lithium-Cobalt chemistry, used in most laptops and mobile phones, has the high energy-density that's discussed, but it's not practical for EV use as it can't manage high power, which causes it to overheat. Lithium-Phosphate (e.g. A123's system) has lower energy density, though still greater than NiMH, but not by nearly as much.

The Prius HV battery only weighs about 40kg (Gen 1 and Gen 2). That's around 3% of the car's weight, and roughly what a child weighs. Savings from switching the battery to a lighter chemistry would be minimal.

More about Lithium Ion here.

Nobody mentioned that Panasonic is purchasing Sanyo yet? It is pending regulatory approval...

[djasonw]

I think everyone here is in agreement that the next gen prius will have Lithium Ion batteries. Just imagine what an improvement that will be. I'm wondering if the 40-80 sweet spot still holds true for those types of batteries.

[drees]

Originally Posted by djasonw

I think everyone here is in agreement that the next gen prius will have Lithium Ion batteries. Just imagine what an improvement that will be. I'm wondering if the 40-80 sweet spot still holds true for those types of batteries.

Depends on the chemistry of the battery, but in general - yes.

[patsparks]

Originally Posted by bwilson4web

Estima ... <grumble> <grumble> <grumble>

The last time I checked, it would cost us nearly $50,000 to import one. $35,000 for the vehicle, $10,000 for shipping and import duties and $5,000 for Japanese lessons. <grumble> <grumble> <grumble>

So one of my day-dreams:


+



The tricky part is rotating the differential 180 degrees so we can drive forward. The other thought is the early VW vans had geared rear wheels. This would also reverse rotation at the cost of more rolling drag.

Bob Wilson

That is the answer Bob.
Mount the Prius engine backwards in the engine bay of the VW van use the geared hubs to reverse the shaft direction and increase torque, both increasing rear wheel torque and allowing the rear facing engine which will fit the standard VW van engine bay better that way.