Battery breakthroughs

[Roy_H]

It seems to me that a battery should work over the temperature range of the car without the need to keep it at room temperature with heaters or refrigeration. It is obviously possible to provide these measures but they are undesirable from cost, reliability, power consumption and bulk. A battery technology which requires external measures to prevent it from destroying itself is a distinctly sub-optimal solution.

Battery 'breakthroughs' are probably best ignored until a safe, intrinsically temperature-robust, inexpensive, energy-dense, fast charging, long-lasting product can actually be bought and used. I suspect we will have quite a wait!

I agree with all your points, just not your conclusion. Each breakthrough brings us closer to the ideal battery as you describe. And it is not reasonable to wait for the perfect solution if interim solutions are cost-effective.

 

[Martin Williams]

Fair enough. I guess we'll each have to respect the other's views and agree to disagree. I suspect the breakthroughs have hit a point of diminishing returns, but time will tell. I could quite possibly be quite wrong.

I guess I'll stick with the ICEs until the best solution emerges.

 

[Pushmi-Pullyu]

It seems to me that a battery should work over the temperature range of the car without the need to keep it at room temperature with heaters or refrigeration. It is obviously possible to provide these measures but they are undesirable from cost, reliability, power consumption and bulk.

Claiming it is "obviously possible" for a battery pack to ignore the need to run within a certain temperature range... is factually incorrect.

Batteries work by chemical reaction. Chemical reactions, by their very nature, operate faster when hot and slower when cold. That's just one of the laws of physics; the Laws of Nature which only science deniers choose to ignore. Sadly for them, denying reality does not actually affect reality.

As Dominick already noted, Martin, the same limitation applies to FCEVs, which also use a chemical reaction to generate power.

Gasmobiles lose energy efficiency at very low temperatures, too. I think I've read that gasmobiles typically lose 15% of their range in bitterly cold conditions. Also, drivers often waste gas by idling the engines for a few minutes to warm them up, which is yet another gasmobile efficiency loss. But people rarely talk about these limitations of gasmobiles; the limitations are so commonly recognized that it's rarely even considered in any discussion of EVs vs. gasmobiles.

It's possible that future batteries will have a wider operating range of temperatures, by using different chemistry. It's possible that they might be able to get along without needing a battery cooling system. However, designing or building batteries so that they don't need a battery heater seems far more problematic. I don't see any way around the physical limitation of sub-zero temperatures making chemical reactions happen significantly slower. Gasmobiles are not immune to this limitation; how can BEVs or PHEVs be immune to that same physical limit?

"You can't fool Mother Nature!" ...contrary to the claims of a certain margarine commercial.
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[Pushmi-Pullyu]

...the Mirai is claimed to reach full operating power in 70 seconds after 17 hours parked in sub-zero temperatures. Perhaps the small size makes the batteries easier to heat quickly? (Perhaps in 70 seconds??) They are used to make up power when demand exceeds the FC output I expect, so one could simply not allow them to be used - at the cost of initially possible sluggish performance - running on teh fuel cell alone until they are warmed up.

"Simply not allowing [the battery pack] to be used" until it's at least somewhat warmed up, appears to be an inescapable conclusion. 70 seconds clearly is not enough time to safely heat up a battery pack, not even a relatively small one. I know that it does take a bit of time for the power on a fuel cell stack to be turned up or down; if that was not so, then a FCEV wouldn't need to use a battery pack for a power buffer. Relying on the fuel cell stack alone for power, is most likely the reason for the 70 second delay in achieving full power for the car, when it's bitterly cold.

 

[Pushmi-Pullyu]

I think if you take a sheet of paper and write down all you want of a 'perfect' battery for an EV - high energy density, low cost, accurate indicator of energy it contains etc etc - a sort of informal requirement specifications - you will find you have listed all the features of a gas tank for an ICE! I have never been an advocate of ICE vehicle and would be delighted to see the end of them, but you have to admit the gas tank seen as a 'chemical battery' is an almost impossibly good act to better.

I've often said something quite similar about the ideal properties for a fuel to power a FCEV. As a fuel, gasoline is so perfectly ideal in nearly every respect; the only place it fails is with emissions from burning it, and from the environmental damage and pollution caused by drilling, pumping, and refining petroleum. If you could change the physical properties of hydrogen to what you'd actually want in a fuel, then it would closely resemble gasoline.

To repeat myself: The problem with fool cell cars isn't the fuel cell, it's the hydrogen fuel.
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[Martin Williams]

Well, I think the sooner they incorporate supercapacitors rather than batteries the better.

I really dislike the idea of anything that is only conditionally stable and requires external arrangements - electronics, heaters, coolers, and microprocessors monitoring the state of charge and so on - to keep them safe. Its fine as long as they are working, but everything has a fault/error rate, unfortunately.

Admittedly, I am probably a bit paranoid about lithium batteries - even for things like phones and laptops - and I always charge them where - if they do decide to go on fire - they will not burn the house down, and keep an eye on them whilst they are being charged! I have seen what even a small one is capable of if maltreated, and it's pretty dramatic.

 

[Martin Williams]

Well, probably the safest place to store it is firmly locked up in a molecule such as a hydrocarbon. But hydrogen has advantages as a fuel too.

It is abundant
It is easy to prepare from a variety of sources allowing a phased transition from petrochemicals.
It can be made from excess renewable power and stockpiled (A growing number of countries have to export excess power now or give it away)
Electrolysis equipment is scaleable, and even a domestic system working with solar panels is feasible
It can be made anywhere, so one is not dependent on other possibly unstable countries for supply of it
It requires no extension of grid power which would certainly be the case if battery cars became ubiquitous.
It allows motorists to adopt it without the need for any change in driving or refuelling habits
It is non-polluting
It allows drivers to enjoy all the benefits of electric vehicles without the disadvantages of batteries.

You will no doubt be able to compile a list of its disadvantages and I will leave you to this, but the most serious one in vehicle use to me is the bulk and weight of the tanks. They seem to be able to accommodate them in quite workable cars however. One might hope that the 'wonder material' - graphite - might be able to help here as it is often advertised as the strongest material known to man.

 

[Pushmi-Pullyu]

Well, I think the sooner they incorporate supercapacitors rather than batteries the better.

That was what got so many people (including myself) excited about EEStor's claims; the claims that they were gonna make supercapacitors with the energy density of li-ion batteries. On paper, supercapacitors are so much better than batteries for storing electrical power! They charge and discharge instantly, without significant heat loss; they don't use chemical reactions to store power, so are pretty immune to temperature changes; and they can be put thru charge/discharge cycles tens of thousands of times without significant loss of capacity.

Yeah, on paper they look great! Sadly, in practical terms, the energy density is hopelessly low, and they don't retain stored power for days, or even for many hours. EEStor's claims turned out to be utterly and completely false. We can realistically hope that with use of graphene or carbon nanotubes, the surface area might be increased to the point that the energy density of future supercapacitors will be competitive with li-ion batteries. But the "leakage" of the power, just from sitting on the shelf for a few hours... that might prove a far harder problem to solve.

 

[Pushmi-Pullyu]

One might hope that the 'wonder material' - graphite - might be able to help here as it is often advertised as the strongest material known to man.

Martin, clearly you have very little or no interest in learning anything about science and technical subjects, but you really ought to learn there is a decidedly non-trivial difference between graphite and graphene, despite the fact they are both forms of carbon. (But then, so is diamond.) Graphene is, at least in theory, the strongest material known to man, and its unique molecular and conductive properties make it potentially a revolutionary material for use in batteries and supercapacitors.

Graphite in powdered form is a useful lubricant, and is used for pencil leads, and has long been a component of commercial batteries, even used in pre-alkaline carbon-zinc batteries. But as an ultra-strong or revolutionary material... not so much.
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[Jim J Fox]

I've often said something quite similar about the ideal properties for a fuel to power a FCEV. As a fuel, gasoline is so perfectly ideal in nearly every respect; the only place it fails is with emissions from burning it, and from the environmental damage and pollution caused by drilling, pumping, and refining petroleum. If you could change the physical properties of hydrogen to what you'd actually want in a fuel, then it would closely resemble gasoline.

To repeat myself: The problem with fool cell cars isn't the fuel cell, it's the hydrogen fuel.
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"As a fuel, gasoline is so perfectly ideal in nearly every respect; the only place it fails is with emissions from burning it"
The OTHER place it fails is enabling terrorism; which may be thought a 'long stretch' but if you apply critical thinking, the inevitable conclusions are 1. Saudi Arabia has been the largest producer of both 2. Much oil happens to be located in Islamic countries 3. The immense wealth is without doubt the means of spreading Islamic doctrine globally.
Thousands of mosques have been financed by Islamic money. According to [Pew] surveys & FBI reports, as many as 80% of these 'places of worship' have been found promoting jihad, Islamic supremacy and world domination in replacing all religions with Islam & its political arm, sharia. Allah must be the one & only God & all must surrender every aspect of their lives to him.
The evidence is now all around us & growing.

Off-topic. But please allow my digression & give this apparent non- sequitur a little thought...

 

[Martin Williams]

But in a fuel cell car, supercaps don't need to store power for long - far less than a day or even an hour. They are required to be chargeable from the fuel cell when it is outputting more energy than the car requires and from regenerative braking, and to return it at high power levels for short intermittent demands such as starting or high acceleration. High energy levels are not required, as these demands are usually short. They are ideal for this.

https://itspubs.ucdavis.edu/wp-content/themes/ucdavis/pubs/download_pdf.php?id=1366

They are getting better too. New ones will tolerate 3v (the old ones would stand only 2.5) This seems a small increase but as the energy is proportional to the voltage squared it makes quite a difference. Hopefully we shall see further increases

I recall the EEStor scam. It was a clear no-no from day one for anyone capable of doing a few sums, but believers were unshaken by such considerations.

 

[Martin Williams]

Martin, clearly you have very little or no interest in learning anything about science and technical subjects, but you really ought to learn there is a decidedly non-trivial difference between graphite and graphene, despite the fact they are both forms of carbon. (But then, so is diamond.) Graphene is, at least in theory, the strongest material known to man, and its unique molecular and conductive properties make it potentially a revolutionary material for use in batteries and supercapacitors.

Graphite in powdered form is a useful lubricant, and is used for pencil leads, and has long been a component of commercial batteries, even used in pre-alkaline carbon-zinc batteries. But as an ultra-strong or revolutionary material... not so much.
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That is what is known as a 'typo'.

I was and am quite aware of the difference between the two, having done some work on an application of graphene in electronics.

But thank you for pointing out my error.

 

[Pushmi-Pullyu]

I recall the EEStor scam. It was a clear no-no from day one for anyone capable of doing a few sums, but believers were unshaken by such considerations.

Your claim for being capable of "doing a few sums" obviously doesn't extend to understanding that the volume and weight of the necessary bulk of ultracapacitors makes it a non-starter to replace the battery pack in a FCEV.

Some EVs do use a small pack of ultracapacitors as a buffer for regenerative braking, but even the comparatively small battery capacity needed to buffer the power from a fuel cell stack in a FCEV cannot, due to practical limits, be replaced with currently available ultracapacitors.
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[Martin Williams]

A simple sum:

To supply 100kW for 10 seconds involves storing a million Joules. Assuming 3v Supercaps, we require C Farads, where

(C/2)x9 = 1000000
C=222,000Farads

You can get 10,000 Farad Supercaps now, so you'd only need 22 of them. They are not TOO big about 2.5" in diameter and perhaps 9" long. The main obstacle is cost, but I suspect that is due to the fact that few are sold. In automotive use, I imagine they would drop dramatically!

I think this is a lot more power than a car would need. I include it only to demonstrate that it is perfectly feasible. It is supported by a number of researchers who have come to the same conclusion (one of which I quoted earlier)

 

[Pushmi-Pullyu]

To supply 100kW for 10 seconds...

...would be wholly inadequate. I think someone said that on startup, the Mirai needs 70 seconds to reach full power. (Fuel cell stacks cannot quickly be powered up and down, unlike either gas engines or electric motors.) So you should be aiming for something a lot closer to 70 seconds than to only 10 seconds! That is, unless you really advocate driving a car that goes into turtle mode every time you stop for a stop light or stop sign.
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[Roy_H]

I think this argument about 70 second start up is silly. First, I am sure the Mirai performs as advertised. Second batteries do not stop working when they are cold, simply are at reduced output. This means you cannot start your frozen BEV and immediately set a new drag racing record, BUT you can drive away.

 

[Pushmi-Pullyu]

I think this argument about 70 second start up is silly. First, I am sure the Mirai performs as advertised. Second batteries do not stop working when they are cold, simply are at reduced output. This means you cannot start your frozen BEV and immediately set a new drag racing record, BUT you can drive away.

Sorry, I didn't explain that fully. I meant the report that a Mirai with a sub-zero battery pack takes 70 seconds to reach full power, indicates that the fuel cell stack takes that long to go from zero to full power output. The Mirai (and other fool cell cars) use a battery pack to supplement power from the fuel cell stack, precisely so they will perform as advertised... at least in normal weather. And I'm not going to "ding" the Mirai for not performing as well in sub-zero weather, since BEVs don't operate at full capacity under those conditions, either. Nor do gasmobiles, but nobody seems to care about that.

BTW -- "Turtle mode" is a term used on EV forums to describe the reduced speed and power of a BEV running with an almost depleted battery pack. Many or most BEVs are designed and built to reduce power for a "limp home" mode when the battery pack is almost drained. The term "turtle mode" does not mean the car can't move!
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[Roy_H]

A cold battery and a depleted battery is not the same thing. You can charge up your car, park it overnight and it will be cold but it has not lost its charge. It just can't put out a lot of power until it warms up.

 

[Martin Williams]

...would be wholly inadequate. I think someone said that on startup, the Mirai needs 70 seconds to reach full power. (Fuel cell stacks cannot quickly be powered up and down, unlike either gas engines or electric motors.) So you should be aiming for something a lot closer to 70 seconds than to only 10 seconds! That is, unless you really advocate driving a car that goes into turtle mode every time you stop for a stop light or stop sign.
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I 'd hoped I'd made it clear that the 100KW for ten seconds was for intermittent demands during normal driving, not to cover the 70 second start up time. Evidently I failed to do so. The 70 second period was quoted for full power after being parked for 17 hours at -30C which implies that you would be able to drive much sooner but might find it a bit sluggish at first.

Driving habits may be different in the USA, but my inclination on starting off at -30C would be to do so pretty gently anyway.

http://blog.toyota.co.uk/nine-surprises-toyota-mirai

 

[Martin Williams]

Pushmi said

"Chemical reaction, by their very nature, work faster when hot and slower when cold. That's just one of the laws of physics..."

Forgive me, but I have to disagree again. Many reactions are exothermic and reversible in which case cooling it can speed up the reaction. Consider, for instance, this simple example:

3H2 +N2 = 2NH3 + heat

Removing heat (i.e. cooling it) from this will result in more ammonia being formed.

As you say, science is not for everyone. There at least we are in full agreement.