lith ion batteries for prius?

I wouldn't bank on any "forthcoming" technologies ever actually making it to market. We have seen others--gas turbine engine, Wankel engine (only one company actually bothered to work it out, and at what price?), fuel cells--come and go. For that matter, several makers have put electric vehicles on the road, then taken them back and crushed them. Lithium ion batteries work in low draw electronics, but they measure things in milliamperes and traction engines hundreds of amperes.

That's incorrect.

Lithium ion batteries work perfectly in high current applications (i.e. laptops), and there are several companies TODAY offering or demonstrating either conversion kits for current hybrids, or from-scratch automobiles with lithium based batteries.

Ike

"bob" ...

There is no need to replace the batteries. They have not been failing in any manner of significant numbers at all. Tomes

It's not because of failures... these are reliable battery packs.

NiMH can be replaced by Lithium-based batteries of the same weight to produce higher capacity and therefore longer drive times. Fewer cells are required, as each NiMH cell is 1.2V while each Li cell might be 3.7V (depending on chemistry), with similar current density (amps per unit weight).

One major issue is safety. With a laptop, temperatures are reasonably controllable. In a car, however, the temperature range can be extreme. Everyone working on hybrid and electric cars is focused on this, and it IS being solved.

I've been considering one of the lithium battery kits for my '04 Prius, but it runs so well that it doesn't make sense to experiment with it. Instead, I'll give it to one of my kids when the HOV lane sticker runs out and buy a lithium battery Prius (hopefully plug-in!) to replace it.

Since much of the grid energy derives from coal, hydro, and nuclear sources, plug-in is a great way to clip the petro umbilical and stop writing checks to people who hate us.

Ike

I'll believe in lithium ion batteries in cars when I see them there, in mass production. Until then, they are just pie in the sky.

Pie in the sky is pretty far from the truth--there are companies working hard at scaling them up to mass production. From a technical standpoint, lithium ion battery packs are well-suited for traction applications. The three biggest reasons why they are not used on a large scale are (1) cost, (2) safety (lithium ion compounds are highly reactive and unstable at high temperatures), and (3) cost. Yes, I listed cost twice because that's the main hurdle in the short term. Few people would be willing to pay the premium, especially when you consider that the NiMH-based hybrids are already more expensive than their conventional engine counterparts. You can also be sure that the folks who get the intellectual property on the solutions that enable scale-up will be in a position to make LOTS of money.

not to mention reduced greenhouse gases? :-) main reason i'm asking about the lithium ions is that i had a job interview a couple months ago with a company in S.C. who makes membranes for lithium ion batts and that said they were going to be in priuses in 2010 - 2011 - was curious if they were blowing smoke, which i believe they were......

bob

There is no way to know.

No. The battery chemistries are different as are their operational characteristics. You really need to have an integrated battery controller that knows job 1 is to protect the batteries.

Do the following experiment, replace some of your NiCD or NiMH battery powered equipment with LiON and tell us how well it works out. You can buy them at Radio Shack.

Use something that is easy to replace. For example, a flashlight.

Bob Wilson

So, give us a clue - what will happen?

By the by, I believe the Prius has a battery controller that does, indeed, put the health of the battery first. No doubt, however, that it won't work for LiON cells.

I also believe that plug-in to charge Prius after market 3rd party upgrades are available (at a huge cost and doubling the current space taken by the factory spec. battery) which give considerably greater range. OK if you don't need the trunk space, I guess........

Chas

Hymotion and Edrive currently offer kits that permit a Prius to be converted to lithium cells and plug-in charging. It's aftermarket, but the Prius Club reports many of them on the road - operating successfully.

Toyota's chairman has publicly announced lithium cells in the 2010 model, to be made available in about a year. Obviously, to make production by that time all the parts sources and procedures must already be properly lined up.

I expect 3-4 different lithium-powered cars with plug-in charging within three years.

Ike

. . .

The only exicting thing I've seen is a GM experiment that put the LiON batteries in an active, environmental housing. They created an actively management environment to keep the LiON cells in their 'safe' range but this of course taxes energy.

Agreed. Although LiON cells have higher energy density, the overhead is the cells have to be maintained in a benign environment and this takes active management.

I think there is a perception problem that hybrid performance comes directly from the batteries. From what I can tell, the batteries are keeping the ICE in energy efficient modes. This is a much smaller energy demand than most folks realize.

The Dept. of Energy ran a fleet study and the 6.5 Ahr batteries were down to 2.6 Ahr after 160,000 miles. Yet the hybrids were still delivering high mileage equal to what they had been doing for the duration of their service. If hybrid mileage were a function of battery energy capacity, it should have decreased over time and it didn't.

The data suggests that round-trip effeciency of the battery system is more important than anything else.

Bob Wilson

good post - i often wondered, how bout a regular 1.5L engine prius, no batts, but the same aerodynamics. i bet it'd be a 45mpg car with similar pickup!

bob

Worse mpg, and you'd be less satisfied with the low end performance.

The traction battery and motor system fills a very small but important gap. The battery capacity can diminish considerably over time (and it will) yet do the job perfectly.

An Otto-cycle engine (like that in the Echo) is reasonably fuel-efficient at cruise, and has reasonable low-end acceleration. The Prius' Miller-cycle engine (not Atkinson, not Otto) is extraordinarily fuel-efficient at cruise, but does a poor job of accelerating from zero at acceptable combinations of engine RPM and transmission ratios. An electric motor, on the other hand, has maximum torque at zero RPM. It's a nice marriage. That is the primary function of the electrical side of the power train - to make the car's initial acceleration acceptable. The "stealth" cruise under 43mph, etc. is a relatively unimportant bonus.

This means that to convert a Prius-style hybrid into an "electric car" requires a massive concept change: expansion of the electric energy storage system, and reconfiguration of the energy management and charging system. It's a transition from the original hybrid concept into an electric car with both plug-in charging and on-board ICE charger.

Nevertheless, I'm considering adding 50 miles of battery to my '04, since I can get lithium cells at no cost and only drive 800 miles a month.

How very succinctly put! Thanks for this - when others ask, I will refer them to this text.

Chas

We have a 2001 Echo and 2003 Prius and both vehicles have the same, 1500 cc engine block. The Echo is Otto cycle and the Prius Atkinson. Both seat 5 and have similar outside dimensions but the Echo trunk is a little larger. However the Echo is about 600 pounds lighter.

The automatic transmission Echo gets 32 MPG and the automatic transmission Prius gets 52 MPG.

Bob Wilson