# Improved batteries for hybrid vehicles



## a_majoor (3 Feb 2006)

Most current hybrids use fairly advanced (and expensive) Nickle Metal Hydride or even more expensive Lithium Ion batteries for the electric portion of the powerpack. Nickle Cadmium (Ni Cad) batteries have too limited a life (and are toxic to boot), while Lead Acid batteries are heavy and have a very short service life.

This company may have found a way to repackage the traditional lead acid battery in a new way which reduces weight, extends service life and reduces cost. (Diesel electric submarines would also benefit....)

http://www.technologyreview.com/NanoTech/wtr_16278,303,p1.html



> Batteries that Don't Die
> 
> New technologies are transforming an old workhorse, promising all-electric lawnmowers and hybrid military vehicles.
> 
> ...



link to read the rest


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## Posthumane (8 Feb 2006)

Hmmm, according to the article, their battery doesn't use lead, but rather a graphite foam. That somewhat offsets the low cost and high availability of lead argument. Still, I'm curious to see how well these perform. If they can in fact match NiMH performance at Lead Acid costs, I think it would give the electric and hybrid-electric vehicle market a bit of a boost.


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## a_majoor (8 Feb 2006)

I was a bit puzzeled by that too, until I remembered the high school chemistry labs (back when handling toxic materials and saftey was guided by common sense rather than a huge rule book...). The reaction takes place with the exposed metal, and re reading the article the graphite simply provides a surface for a thin coat of lead to be applied. Contrast this to your usual "Motomaster" battery where the plates are mostly sheets of lead, and much of the metal never takes part in the reaction, being "buried" inside the plate.

This is probably worth following just for the weight saving alone, cutting weight in cars increases fuel economy (and there would be a small follow on effect, lighter batteries need lighter battery trays, which mean other parts don't have to be so strong, which means they can be lighter as well. This might only amount to a 2% saving, but every bit counts) and you can imagine the size and weight involved in large emergency battery packs for local power supplies (switchboards, cell phone towers etc.), not to mention Diesel electric submarines.


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## Wookilar (13 Mar 2006)

I was reading this as well. The only issue that I can see (and here I'm trying to remember Electrical section a decade ago  :-\) is this "thin coat of lead" on the plates. I can see these becoming ineffective in a short period of time due to a build up of..........bloody heck, what is it that it turns into?........... The same thing happens to deep cycle batteries and when they go dead, you have to put them on a pulse charger for x hours to get the plates de-........... before you try to charge them. Crap. Informative post I have going on here.

Somebody help an old mechanic out here, What's the chemical reaction of lead plates that eventually degrades to a state where it will not hold a charge anymore? I want to say calcium, but that's not sounding right. Essentially, the lead plates end up being "coated" and no more chemical reaction is able to take place (it's not really coated, but an actual change in the compostion from the reaction of the electrolyte and the lead).

Anyone?  ??? ???


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## Wookilar (14 Mar 2006)

SULFATE!!! The chemical reaction in a lead/acid battery can lead to sulfation of the plates. This essentially leads to the plates being plated in sulfates which stop the chemical reaction. To save deep cycle batteries, you must put them on a pulse charger for a long time (5 days is the number I remember) to de-sulfate the plates. Then, you can recharge.
The sulfation is caused by the continual charge/drain cycle that many heavy load (electrically speaking) appliances . Anyone had LSVW batteries go dead in a CP? They're not supposed to, but they do.
With just a "thin layer" of lead on these plates, I would really be concerned about the longevity of these systems. I have to wonder if this is more of a spring-board technology instead of a real solution. Very interesting application though, must keep my eye on it.


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## a_majoor (17 Mar 2006)

I wonder if the "sulphate" problem can be avoided by using a different electrolyte than sulphuric acid?


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## Wookilar (17 Mar 2006)

A different acid base? I don't know if that will work, but I do know a few young Chem Eng types. I'll see if I can pick their overly large brains about it. If I hear of anything, I'll post it up.


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