Nickel-cad hybrid batteries -- soon to be obsolete?

[akirby]

Did not realize there were 2 different types of CVTs. Thanks for the info!

[AptosDriver]

Llolder: Thanks for all that good information! And especially for the link to the Toyota CVT planetary gear design. :beerchug:

Edited February 7, 2011 by AptosDriver

[Oman]

Hmmm, marketspeak. LiPo has better power to weight ratios than the others. The statement that they can better handle physical damage is complete bunk though... the reason Hyundai had to work so hard with them is to try to design a casing that reduced the chances of physical damage and an interconnect system with multiple break points to try to prevent catastrophic runaway. The risk (outside of the chemistry itself) is directly related to its energy density and rapid discharge ability. I've been working with LiPo packs for several years now and they can be extremely violent when mishandled. The thing you can say about the Ford NiCD system is that it is reliable, well understood, and safe.

 

I think everyone will be moving to LiPo systems in the future. Someone has to be first... just not me. I want a few years more improvement on the tech first in an automobile environment. The article also mentions laptops but forgets that iPods and such use tiny little LiPo packs.

 

When a LiPo pack is pierced the reaction is instant and violent. I don't have a GOOD link handy but I do have a link to a couple of, well, not too bright, folks who shot a small LiPo pack with a 357. The pack is INSIDE a metal tool box. Now imagine 200x this much material behind your back seat in an accident.

 

(ate my link - try again - http: //www.youtube.com/watch?v=9eqbTLwVynE - had to add a space after the HTTP)

 

 

Jon

 

 

The new lithium batteries in the Sonata and Kia hybrid sedans should not be confused with lithium-ion batteries. They're lithium-polymer batteries and as I've learned from this article, there's a difference:

 

The lithium polymer battery

 

The Hyundai Hybrid Blue Drive is the only system in the market that uses lithium polymer battery technology, which is far more advanced than the competition's nickel-metal hydride and lithium-ion applications.

 

What's unique and high-tech about lithium polymer is how it improved on the lithium-ion technology, which is used in laptops and cell phones. Hyundai upgraded this technology by adding robustness, power-density and package flexibility ....

 

Lithium Polymer vs. Nickel-Metal Hydride

 

Hyundai Sonata's lithium polymer battery improves the nickel-metal batteries. Although both batteries pack the same amount of power, the lithium polymer comes with 20-30 percent less weight, 40 percent less volume, and 10 per-cent greater efficiency, as well as 1,7 times more energy density.

 

This allowed Hyundai designers and engineers to devote less space and weight originally for the battery pack. The lithium polymer can better resist temperature change and can hold its charge 1.25 times longer.

 

Lithium Polymer vs. Lithium-ion

 

The traditional lithium-ion battery is reliable and easy to handle. However, they lack packaging efficiency and their small parts are complicated to manufacture. Lithium polymer batteries, on the other hand, have higher energy density yet lower manufacturing costs.

 

It can better withstand physical damage and begins to discharge only after a considerable number of charge-discharge cycles. Lithium polymer technology definitely has advantages in thermal robustness and safety.

 

The major advantage of lithium polymer is the efficient packaging of its anode, cathode, electrolyte, and encasement material.

 

Another positive difference is that lithium polymer uses a polymer gel as the electrolyte, rather than the traditional liquid electrolyte. This allows the use of a thinner and lighter encasement or pouch with aluminum walls.

 

New Hyundai technology

 

The lithium polymer battery is a product of hundreds of hours of testing and research by Hyundai and its battery supplier, LG Chem. This new technology has been proven to have better thermal and mechanical stability than other existing systems for better and safer driving.

 

It is also much cooler than the nickel-metal hydride and lithium-ion batteries, which means it can guarantee maintenance-free battery operation for a good 10 years or 150,000 miles in any weather conditions.

 

Then there's this from Popular Mechanics:

 

Compared to nickel-metal-hydride batteries of the same output, such as those used in the hybrid versions of the Toyota Camry and the Ford Fusion, the lithium-polymer batteries are 35 percent lighter and 40 percent smaller. Therefore, they can more easily be packaged without adding weight and taking up cargo space. They also have a lower self-discharge rate, which improves on the tendency to lose electricity when the vehicle is parked.

Compared to lithium-ion batteries, such as those used in electronic appliances, lithium-polymer batteries offer a similar energy density but with lower heat generation, which improves cycle life.

 

...The difference between lithium-ion and lithium-polymer is in the chemistry and packaging. Engineers seeking to take advantage of lithium-ion's superior power density have battled its tendency to overheat and degrade as charge cycles accumulate.

 

In other words, lithium-polymer batteries are longer-lasting and much less prone to catch fire than lithium-ion batteries. The Kia Optima hybrid uses the same battery technology and drive train as the Hyundai Sonata hybrid discussed here. GM uses lithium-ion batteries in its Chevy Volt. It will be interesting to see how those work out.

 

Edited February 7, 2011 by Oman

[AptosDriver]

Hmmm, marketspeak. LiPo has better power to weight ratios than the others. The statement that they can better handle physical damage is complete bunk though... the reason Hyundai had to work so hard with them is to try to design a casing that reduced the chances of physical damage and an interconnect system with multiple break points to try to prevent catastrophic runaway. The risk (outside of the chemistry itself) is directly related to its energy density and rapid discharge ability. I've been working with LiPo packs for several years now and they can be extremely violent when mishandled. The thing you can say about the Ford NiCD system is that it is reliable, well understood, and safe.

 

I think everyone will be moving to LiPo systems in the future. Someone has to be first... just not me. I want a few years more improvement on the tech first in an automobile environment. The article also mentions laptops but forgets that iPods and such use tiny little LiPo packs.

 

When a LiPo pack is pierced the reaction is instant and violent. I don't have a GOOD link handy but I do have a link to a couple of, well, not too bright, folks who shot a small LiPo pack with a 357. The pack is INSIDE a metal tool box. Now imagine 200x this much material behind your back seat in an accident.

 

http://www.youtube.c...h?v=9eqbTLwVynE

 

Jon, that video is truly sobering! Thanks.

Edited February 7, 2011 by AptosDriver