On wednesday I attended a conference named 'Car 2.0' organized by business students at UC Berkeley & Stanford Univ. It was an excellent conference and I'm still digesting everything that was said.
One of these was an observation that cell prices have fallen dramatically but does that mean the prices for finished batteries are falling?
There's a distinction some might not grok... In lead-acid batteries we're accustomed to buying a whole battery that comes in 12volt size, but with little awareness that the battery is made of 6 cells. That's because the lead-acid battery packages the cells into a neat box to make assembling a battery system easier. With lithium though we're getting individual cells. You could just get some cells, put them in a box, wire up connectors between them, and declare it a battery. But you're likely to lose a lot of expensive lithium cells to too-deep a discharge or overcharging. Hence a complete lithium based battery is packaging, BMS, perhaps cooling fans, perhaps a charger...
In the conference that was the question raised - whether battery prices are truly falling. The people on stage were from Coda, Aptera, and a guy who'd helped launch Tesla but had been pushed out.
To answer the question they discussed that difference between a collection of cells and a proper battery. And they pointed out that the car manufacturers are being very opaque about the costs of the components used to build the cars. Hence it's hard to tell whether GM's or Nissan's or Honda's (etc) price for battery systems is falling, or climbing, or what.
We can look at websites of the vendors catering to us hobbyists - and see that the prices we pay for cells is falling. But maybe that has more to do with Thundersky's business than anything about whether the overall lithium battery market is seeing a price decline. But it seems likely that if/since cell prices are falling, if the other costs remain constant that prices for battery systems would also be falling. But at that there's a dependency on how large the cell price is to the price of a battery system. For example if other costs like labor dominate the cost of the battery system, then cheaper cells won't make much difference to the final battery price.
I've always wondered about this. Why do large manufacturers still use these tiny cells (relative to overall battery size). E.g. the Chevy Volt has 288 cells per battery pack. That seems like an inordinate amount of:
It seems like it would be more efficient to create single-cell batteries, or at least use larger cells that don't require hundreds of them being put together. Not only would you save weight and volume, but less wiring means less resistance/heat as well. So is there some kind of advantage to having hundreds of individual cells over a handful of large cells?
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Well, Tesla has proved they can build a good car with tiny cells. And they are exporting this idea to Toyota. And Martin Eberhard is now working for VW Research, and pursuing tiny cells to make a large pack at VW.
They claim that - the tiny cells are under more rapid R&D because of the consumer electronics industry.
I'm with you though - each element in a system is subject to random failure and the more elements in the system the more likely that an individual element in the system will fail. Plus it makes assembly and everything more complex.
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just a wild guess here, I'll let the pros shoot it down if needed..... The smaller cells do offer one thing, more reactive contact area of the battery chemistry. Larger cells would still need an elaborate interior design to disperse the reactive chemicals amongst each other. A larger version of a small cell would have mass areas of inactive chemicals, simply because they werent close enough to other components to react. If the volume of the design is all that changes, it may not render the increased capacity that accumulated smaller cells provides. Just think of all the elaborate exterior monitoring and control hardware needed to maintain those packs, internalized, it might become more problematic to regulate these cells. Disclaimer: Honestly, I dont know a thing about building battery cells, so your idea is just as good, probably better than mine. :-)
Well, this is how I envision it based on my limited understanding of how batteries work:
It's basically just a giant prismatic li-ion battery. I didn't include the anode/cathode tabs, the insulators/gaskets or the PTC switch, but you get the idea. It shouldn't be that much more elaborate than the small-scale battery cells. But there may be nuances to the chemistry involved that just don't scale up and require a different approach, and that may be why the R&D for small-scale cells just don't apply to larger cells.
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I think the fundamental issue is the voltage that the particular chemical reaction of a battery type generates.
For NiMh it's 1.25V, for Lead-acid 2.1V, for Lithium around 2.5V etc .
Unless the battery pack is a serial-parallel pack or a parallel pack, increasing the cell size will not change how many cells are needed!
A light, super-efficient DC/DC converter would solve the problem: Use a massive single 2.5V cell (of, say 100000Ah capacity) and convert the voltage to whatever is needed - maybe 500V DC or thereabouts. Unfortunately, such a converter has not been invented, yet....
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Interesting... I sorta speculated that voltage limitations might be a factor. However, I figured that deep-stacking the electrode layers would solve that. And instead of connecting multiple smaller cells in parallel in order to increase current, you would just increase the electrode surface.
I suppose using a bunch of small individual cells in a serial-parallel pack gives you more freedom in terms of the overall shape of the battery (since they don't need to be arranged in a particular way to be wired in parallel or in series). But most EV/hybrid battery packs aren't that irregular in shape. You could probably still get whatever voltage and current you needed using a handful of large cells and still fit them in the battery pack.
I'm thinking it could possibly be a manufacturing quality problem like they have with LCDs. Manufacturing large sheets of electrodes without any defects may be difficult. And you lose much more product for each defect versus manufacturing smaller cells.
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The cost of testing a new cell format size would be huge.
As batteries store energy and the risks of internal failure can be severe the testing is thorough. Blah Blah
If a battery pack needs to be customised to fit in an EV then using smaller proven modules that WHEN fail are small packets of energy then the risk of run-away failure is reduced.
Automated manufacturing and the material handling involved is perfected to a lower cost per unit when the items are easily manipulated by automation. Rolled layers that make cylindrical cells are easier to handle than things like a deck of cards.
I used to repair automated equipment that made power factor correction capacitors.
Also the air space between cells is important for cooling if a failure occurs. I think thats why Sky-Energy and TS cells have ridged surfaces.
Has anyone got pricing from this company on either their Lithium Cobalt or Lithium Iron cells
www.internationalbattery.com/products.php
www.internationalbattery.com/technology
If your a manufacturer and supply a warranty then supply pouch cells may be tad difficult as a pouch cell might be fine as a single cell in the bottom of an Ipad or Netbook but when staked like books the heat can build up as the ratio of surface area to volume decreases.
I'd like to know the break down of a 100Ah cell into it's parts:
Anode metal,
Cathode metal,
Electrolyte
Seperator
Casing materials
Fusing, PTC
End-terminals
Plus Cell Circuit or BMS
As many have mentioned there isn't that much lithium in Lithium battery.
Have battery packs for Laptops decreased in price?
Who is keeping a track on the price?
2010 100Ah LiFePO4 $180 for one off so how much for 1M AHh -60%???
2000 ?????