TheEEStory.com

Tec wrote:

I've lost count of the number of reports of various groups who announce batteries with improved energy densities, charging rates, or other desirable quantities, but then they seem to fade out of existence.

I think the trouble is that solving ONE of these problems is only solving part of the problem and in order to do it, some other desirable feature has to be sacrificed. Unfortunately these sacrifices are rarely mentioned in the announcement

I wonder if it would be possible to quantify our assessment of what is and what isn't a 'good' battery by making a rough individual assessment of each feature and adding the total. I suggest this be pretty coarse - say -2 to +2, eg:

-2 Lousy
-1 Worse than average
0 Average
+1 Better than average
+2 Excellent.

This could be applied to the following features:

                Lousy   Poor  Usable    Good    Fine
Energy density    100    175     225     300     500 (Wh/kg)
Cost             1000    700     500     300     100 ($/kWh)
Charge rate         0.05   0.2     1.0     3.0    20.0 (C, continuous)
Discharge rate      1      3       6      10      20 (C, instantaneous)
Temp. tolerance    10     30      50      70     100 (range, K)
Charge cycles     300   1000    3000    6000   10000 (to 80%)
Losses in cycle    50     10       3       2       1 (%)
Degradation         1      3       8      12      30 (years)
Safety        Explodes  Burns Sputters Outgasses Stable (?)

I've abandoned average as it moves.

An at spec EESU would be in the top category in all of these except the first, I think.

Last edited Mon, 04 Apr 2011, 5:41pm by WalksOnDirt

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Perhaps we should have an 'Existential status'
ranging from 'Myth' to 'Real' via 'Theoretical', 'Claimed', and 'Corroborated'. Otherwise what you've proposed seems a good start. What does (C, continuous) and (C, instantaneous) mean? And I think for temp. tolerance we need an operating range rather than a single temp.

I guess we would descend to a shouting match pretty quickly if we considered where to put the EESU, but I was really thinking of this for batteries, not capacitors, mainly because it seems not possible to meet them all well in their case, and there are so many announcements of 'breakthroughs' in one area which are negated by poor performance in the others.

Tec wrote:

What does (C, continuous) and (C, instantaneous) mean?

This is a common "unit" for batteries. For charging it tells the maximum charge current in respect to capacity. When the capacity is 50 Ah, a maximum charge current of 1C is 50A, 2C is 100A and so on. When the capacity is given in kWh and the battery has a capacity of 20 kWh, then C tells the maximum charge power, i.e. 1C means charging with 20 kW and 20C means a charge power of 400 kW. Or, in other words, 20C would allow you to charge an empty battery completely full within 3 minutes.

I would say that 10C would already be very excellent and would allow long range drives even with a rather small battery, if the infrastructure for charging would exist.

Discharge of 20C is ridiculous. Who would need 1000 kW power in a car with a 50 kWh battery? 5C would be more than sufficient in any case and even for fast sports cars.

Thanks for the clarification, chacha.

I suppose there might be external applications where a 20C discharge rate would be useful. I'm not suggesting a little arc-welding at the side of the road, but perhaps there is other equipment where it would be convenient to have plentiful power available, even if it meant draining the battery in minutes.

chacha wrote:

Discharge of 20C is ridiculous. Who would need 1000 kW power in a car with a 50 kWh battery? 5C would be more than sufficient in any case and even for fast sports cars.

What's good depends on the usage. If you have a 5 kW battery in a hybrid 20C might be useful. (Alright, I just thought that up. You are right.)

Tec wrote:

...I was really thinking of this for batteries, not capacitors...

This is a site about EEStor, so I think including an EESU is appropriate.

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...I think including an EESU is appropriate.

If you wish. I've no objection, but what are you going to say about it? There's been nothing new about it for well over a year now.

Tec wrote:

...I think including an EESU is appropriate.

If you wish. I've no objection, but what are you going to say about it? There's been nothing new about it for well over a year now.

So? I could also say: If leprechauns exist, and they have pots of gold, it would be nice to catch one.

Not really appropriate here, though.

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This all needs to be in context.

1 usable kWh/kg is what I find to be minimally acceptable (usable) in small to mid-sized vehicles. Good for most vehicles would be 4 usable kWh/kg.

In terms of cost to the end user: You need $60-65 per usable kWh to be minimally acceptable (usable). Good would be $15 per usable kWh.

These would be at the end of life under worst conditions. Adjust these for any changes in capacity at average charge rate of 10 MW (good, 3 MW is minimally acceptable) and any other capacity altering factors.

Last edited Tue, 05 Apr 2011, 4:28am by student

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I am aware that the EV industry believes the game will change vis a vis ICE vehicles when the batteries cost USD250 per kwhr or less.

So while Zenn tout $100, I believe that if the industry group is right, then ZMC could be wildly successful if the batteries cost 50% more.

kind regards
ei

WalksOnDirt wrote:

Tec wrote:

...I think including an EESU is appropriate.

If you wish. I've no objection, but what are you going to say about it? There's been nothing new about it for well over a year now.

So? I could also say: If leprechauns exist, and they have pots of gold, it would be nice to catch one.

Not really appropriate here, though.

We seem to be in complete agreement here then. Perhaps EESUs and leprachauns could be intoroduced when incontrovertible evidence that they exist is produced?

As for discussion about cost and energy density, the other parameters are equally important. A battery that has to be maintained within 5 degrees of room temperature at all times or it fails permanently would not be acceptable even if it were low priced and sufficiently energy dense.

student wrote:

This all needs to be in context.

1 usable kWh/kg is what I find to be minimally acceptable (usable) in small to mid-sized vehicles. Good for most vehicles would be 4 usable kWh/kg.

This is nothing less but stupid.

Nobody cares much about wether a battery in a car has an energy density of 0.2, 1.0 or 4.0 kWh/kg. With an energy density of 1.0 kWh/kg an EV would already weigh less than a ICE-driven car with the very same drive range. But 0.2 kWh/kg, which is available today, would be perfect for all uses in cars. Today the success of EVs does not depend on better energy density of batteries, but on lower cost!

Tec wrote:

As for discussion about cost and energy density, the other parameters are equally important. A battery that has to be maintained within 5 degrees of room temperature at all times or it fails permanently would not be acceptable even if it were low priced and sufficiently energy dense.

Since it is not technically difficult to keep a battery within 5 degrees of room temperature at all times, such a battery would certainly be acceptable. Even the ZEBRA battery would be acceptable, and this must be kept over 250°C at all times.

Well, you might accept them...

Tec wrote:

Well, you might accept them...

... and not only me, but Daimler and BMW too.

student wrote:

This all needs to be in context.

1 usable kWh/kg is what I find to be minimally acceptable (usable) in small to mid-sized vehicles. Good for most vehicles would be 4 usable kWh/kg.

In terms of cost to the end user: You need $60-65 per usable kWh to be minimally acceptable (usable). Good would be $15 per usable kWh.

These would be at the end of life under worst conditions. Adjust these for any changes in capacity at average charge rate of 10 MW (good, 3 MW is minimally acceptable) and any other capacity altering factors.

All this would approach outer reaches of making sense only if 1. people were building EVs by adding equipment to existing cars (and not removing anything), and 2. drivers would be forbidden by law to change their filling up habits to more convenient ones (charge at home).

Otherwise, it's pure lunacy:).

chacha wrote:

student wrote:

This all needs to be in context.

1 usable kWh/kg is what I find to be minimally acceptable (usable) in small to mid-sized vehicles. Good for most vehicles would be 4 usable kWh/kg.

...Nobody cares much about wether a battery in a car has an energy density of 0.2, 1.0 or 4.0 kWh/kg. With an energy density of 1.0 kWh/kg an EV would already weigh less than a ICE-driven car with the very same drive range. But 0.2 kWh/kg, which is available today, would be perfect for all uses in cars. Today the success of EVs does not depend on better energy density of batteries, but on lower cost!

I am a business person chacha, not a bleeding heart green as you are. I invite you to provide data to reinforce your fluffy claims. I suggest you only have more bogus fluff to offer.

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student wrote:

I invite you to provide data to reinforce your fluffy claims.

I know you think you need to get 500 mile range in the snow. I think you can do that with 500 Wh/kg batteries, but they would be large; nearly the size of the Tesla Roadster's. That has 135 Wh/kg batteries.

I would be happy with 250 miles in nice weather, which you can get with 200 Wh/kg batteries.

Last edited Tue, 05 Apr 2011, 9:51am by WalksOnDirt

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WalksOnDirt wrote:

I know you think you need to get 500 mile range in the snow. I think you can do that with 500 Wh/kg batteries, but they would be large; nearly the size of the Tesla Roadster's. That has 135 Wh/kg batteries.

I would be happy with 250 miles in nice weather, which you can get with 200 Wh/kg batteries.

I would put 500 Wh/kg in the poor column. 200 Wh/kg might qualify for the lousy column.

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student wrote:

chacha wrote:

student wrote:

This all needs to be in context.

1 usable kWh/kg is what I find to be minimally acceptable (usable) in small to mid-sized vehicles. Good for most vehicles would be 4 usable kWh/kg.

...Nobody cares much about wether a battery in a car has an energy density of 0.2, 1.0 or 4.0 kWh/kg. With an energy density of 1.0 kWh/kg an EV would already weigh less than a ICE-driven car with the very same drive range. But 0.2 kWh/kg, which is available today, would be perfect for all uses in cars. Today the success of EVs does not depend on better energy density of batteries, but on lower cost!

I am a business person chacha, not a bleeding heart green as you are. I invite you to provide data to reinforce your fluffy claims. I suggest you only have more bogus fluff to offer.

It's as simple as it is: most people and much more most business people don't care much about the weight of their car. If they would, they wouldn't happily buy SUVs with a weight of almost 3 tons.

Nobody cares much about 300 kg more weight, when this results in less energy consumption. For business people cost is the relevant parameter, for greens it's energy consumption. You are neither in business nor are you green.

TEC,
What happened to your original topic on this? Did you delete it?

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Bretspot wrote:

TEC,
What happened to your original topic on this? Did you delete it?

Coward :)

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Bretspot.

I'm as puzzled as you are. I certainly didn't delete it. Perhaps its some slack-jawed moderators idea of fun.

I would ordinarily ignore a deleted topic, but in this case I had already spent half an hour on my reply. Besides, I didn't see anything about this topic that was worse than many others. (I had been hoping Tec had deleted it himself, although it didn't really seem likely.)

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chacha wrote:

It's as simple as it is: most people and much more most business people don't care much about the weight of their car. If they would, they wouldn't happily buy SUVs with a weight of almost 3 tons.

Nobody cares much about 300 kg more weight, when this results in less energy consumption. For business people cost is the relevant parameter, for greens it's energy consumption. You are neither in business nor are you green.

More fluff. Nice chacha.

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student wrote:

WalksOnDirt wrote:

I know you think you need to get 500 mile range in the snow. I think you can do that with 500 Wh/kg batteries, but they would be large; nearly the size of the Tesla Roadster's. That has 135 Wh/kg batteries.

I would be happy with 250 miles in nice weather, which you can get with 200 Wh/kg batteries.

I would put 500 Wh/kg in the poor column. 200 Wh/kg might qualify for the lousy column.

Don't be a fool. 500 Wh/kg would give you 100kWh for the same weight as an ICE. If cost were acceptable and charging stations were widespread it would be game over for ICE cars at that energy density.

CpctT@0R wrote:

student wrote:

WalksOnDirt wrote:

I know you think you need to get 500 mile range in the snow. I think you can do that with 500 Wh/kg batteries, but they would be large; nearly the size of the Tesla Roadster's. That has 135 Wh/kg batteries.

I would be happy with 250 miles in nice weather, which you can get with 200 Wh/kg batteries.

I would put 500 Wh/kg in the poor column. 200 Wh/kg might qualify for the lousy column.

Don't be a fool. 500 Wh/kg would give you 100kWh for the same weight as an ICE. If cost were acceptable and charging stations were widespread it would be game over for ICE cars at that energy density.

We all have different parameters, don't we? 500 usable Wh/kg would hypothetically give the Leaf as much as ~ 150 kWh. This is 480 miles of 2011 EPA range. That's range-competitive with the Versa.

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Tec wrote:

Bretspot.

I'm as puzzled as you are. I certainly didn't delete it. Perhaps its some slack-jawed moderators idea of fun.

My apologies Tec. :)
Yeah I wonder where that topic went after all. I'll ask someone who has access to the change back-log.

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