Will Electric Vehicles Be Viable? When?

[Ferry]

I'm merely pointing out that in Australia and the USA this is very common use case for vehicles - we will happily drive 200kms and back for a weekend away.

Most if not all modern EVs can cover 200 km. It's a typical weekend trip here in Norway. Travel to the cabin in the mountains Friday afternoon, back on Sunday evening. My family's cabin is 150 km away. That's ok even on the worst winter day. We usually stop on the way to buy food and things for the weekend, and sometimes we charge a bit when the car is parked anyway. But rapid charging is generally quicker than shopping. We don't have electricity installed in that cabin, so we have to charge sometime during the weekend, either Friday night or Sunday on the way home. Most other trips we charge overnight when we visit our parents or friends.
I'll admit I sometimes wish the car had longer range. But I can easily buy that any day. There's only one detail that hinders me; the price.. So I try to think about the money I save by NOT buying that other car. If I divide that money by the time I charge, it's like $500/hour saved. Often the car needs just a tiny bit more charge to get us home. The last charge lasted 7m2s.

[joshuagore]

in a way the range reduction is built-in from day 1
(to make the battery warranty hold up the car is arranged normally to use only about 35% of its full capacity ie range)

presumably if there is now improved battery life this would appear (already ?) as some of .....
increased warranty life
increased range
range/life unincreased but battery cost/weight reduced

75%-85% is closer to what I've found. Anything I have tested is charged to 85% as new and increased to 100% over the life of the battery (your chemistry may vary) . Maybe less would be more fruitful but it would also limit the range when new to the point of effecting the products utility. In a car this may be easier to accomplish but on a bike it really does ad significant weight if i'm assuming packaging 50% more battery, especially considering the battery is swap-able. I have never heard of a battery being used at 35% state of charge, but I do know most oem's have very specific charging cycles which maximize both range and reliability against charging cycles.

Let me see if I got this right. You mean that when an EV is sold, the battery is used maybe from 35% to 85% wich provides the advertised range, but year by year that margin is increased, using the battery from 32 to 87% after some time of use, 30-90% some years later, and at some point battery is used from 0-100%, so battery capacity reduction due to age is compensated and the EV keep a similar range during all its lifespan?

That´s interesting

that sounds about right to me although I'm sure my battery guy would prefer a more technical explanation as I think the way different companies go about it is different. We use state of charge but I think other people use a battery management system to harness several discrete batteries to be used in parallel or series. I could imagine using high discharge batteries in concert with higher density storage to achieve more that I can with state of charge.

The reason I think others use different setups is because a Tesla prepares the battery to be in Ludacris mode... I don't know how this would be done with one monolithic battery, but I'm also not the expert on that stuff.

[Andres125sx]

that sounds about right to me although I'm sure my battery guy would prefer a more technical explanation as I think the way different companies go about it is different.

If you have the chance, please ask him. I´m curious as I would have never done that myself for the exposed reasons of accelerated degradation

I could imagine using high discharge batteries in concert with higher density storage to achieve more that I can with state of charge.

Last gen Formula E batteries are exactly that, they´ve achieved double energy density with that so now they don´t need a car swap

[Andres125sx]

getting 6 or 7 years warranty by (covertly) limiting the (working) range to the 35% capacity between 35% and 70 %
(not the 35% between 0% and 35%)
nothing bad about this of course

I´ve just realiced about something wich now looks obvious, but wich has not been commented. If current batteries are limited to 35% of capacity to improve longevity and provide a sensible warranty, then the problem of current batteries is not energy density, but longevity, as current batteries can provide x3 the range wich EVs achieve today. Ok then they would last one year as any other lithium battery and none would purchase an EV whose battery will need a replacement in one year, but the fact is current batteries energy density can provide triple of the advertised range, so its longevity what need to improve more than energy density

I was wondering about Nikola anouncement about their new batteries with double the range, maybe their achievement was to improve longevity even if it´s same technology so they can provide same warranty using more % of its real capacity

[joshuagore]

getting 6 or 7 years warranty by (covertly) limiting the (working) range to the 35% capacity between 35% and 70 %
(not the 35% between 0% and 35%)
nothing bad about this of course

I´ve just realiced about something wich now looks obvious, but wich has not been commented. If current batteries are limited to 35% of capacity to improve longevity and provide a sensible warranty, then the problem of current batteries is not energy density, but longevity, as current batteries can provide x3 the range wich EVs achieve today. Ok then they would last one year as any other lithium battery and none would purchase an EV whose battery will need a replacement in one year, but the fact is current batteries energy density can provide triple of the advertised range, so its longevity what need to improve more than energy density

I was wondering about Nikola anouncement about their new batteries with double the range, maybe their achievement was to improve longevity even if it´s same technology so they can provide same warranty using more % of its real capacity

I wouldn't say that most batteries could provide 3x the range. That seems like a gross overestimate. I would say most account for 15% degradation in charge voltage over 3-5 years. Some have failed with their charging cycles and offered far less performance.

Here is some ev battery data, not sure if it has been shared yet.
Tesla Battery Data user submitted:

Leaf Study..
https://www.nimblefins.co.uk/study-real ... erioration
http://www.wind-works.org/cms/index.php ... ad0bbfc94d

EV Car Comparison..

[Brake Horse Power]

Strange theory this limited working range because of warranty.

Let's say a standard battery degredates about 20% after 2000 cycles. There is no reason to limit the working range, it just degredates over time and that's also how the warranty is set up. The new electric volvo XC40 has a warranty of minimal 78%range after 160.000km or 8 years whichever comes sooner. But they expect the batteries to do 20% degredation after 250.000 to 300.000 km (1500 cycles).
Also range is the biggest selling point, it doesn't make sense to reduce the range..

[Big Tea]

read yesterday that the new Fiat 500 electric (FROM £29k ) will have a 'get you home' facility of a 5 min charge for 30 miles. Dont know how many of these high power chargers wil be available, though it sounds like a very useful idea.

[Andres125sx]

Strange theory this limited working range because of warranty.

Let's say a standard battery degredates about 20% after 2000 cycles. There is no reason to limit the working range, it just degredates over time and that's also how the warranty is set up. The new electric volvo XC40 has a warranty of minimal 78%range after 160.000km or 8 years whichever comes sooner. But they expect the batteries to do 20% degredation after 250.000 to 300.000 km (1500 cycles).
Also range is the biggest selling point, it doesn't make sense to reduce the range..

It does when you consider Deep Of Discharge (DOD) and State Of Charge (SOC) has a direct impact on the number of cycles the battery will provide. Battery degradation depend, heavily, on both parameters. With a 100% DOD and 100% SOC that 20% degradation would probably appear in 20.000km as much, while with a 70% DOD and SOC, a 20% degradation would need half million km (invented numbers) or even more.

Range is key in selling numbers, true, but, what do you think would be the selling numbers if a 20-30k$ car would need a battery replacement (half of car price) each 2 years? That´s what any lithium battery last, as much. Look at the batteries into your phone, laptop, screwdriver, toothbrush...

EVs use exactly same batteries (18650 lion, or 20700 wich is the same a bit bigger) and the only way to improve that short lifespan, is limiting both DOD and SOC.

So if numbers are what Tommy Cookers said (around 35% of real range used), that means any EV could provide triple the range than it actually provides. Then the battery will only last 1 year, but thats my point, problem of current batteries is NOT range, but longevity, range, wich is ok, is cutted down to reduce the real problem, very short cycle life


https://energymag.net/dod-depth-of-discharge/

[Brake Horse Power]

The AESC cells used in the latest Nissan leaf degredate 15% after 2000 cycles under a relatively low C-rate and 25 degrees celcius.

The leaf has a 60kWh pack, so ±300km range. If you multiply that by 2000 cycles.. Now the conditions are worse in real life temperature wise and maybe sometimes higher C rates but still. I don't see why it is would be a problem, and these are air cooled cells..

Now the difference is in the pack size. Small pack, lots of cycles, more degredation. I agree that it can be improved which is what Tesla claims (and probably will) do. As do others. But I miss the evidence which supports the claim that the batteries are tuned back. Off course there is the D.O.D. Thing, these Nissan cells can be discharged 90%, that is limited. I suppose they are all around that 85% - 90% ballpark. Lithium Iron Phosphate cells I sometimes see with 80% max D.O.D. They can do some 4000 cycles and are more used in heavy duty. Also rumors go Tesla uses them in the CATL packs for the Chinese model 3. So since these LFP packs just do in general twice the cycles as NMC it is not that groundbreaking. The issue with LFP is that they are in general more heavy and voluminous than NMC. Nano technology is going rapid now in battery land which is used to increase capacity. More capacity per cell means less cells needed and reduces weight. If you can maintain the cycle life than you have the new Tesla battery..

Another thing which could reduce the usable capacity of the battery if there is a significant voltage rise or drop when at 0% or 100%. At 0% is not a problem because of D.O.D. and if you are a smart car manufacturer you make sure the system can cope with the voltage rise. Otherwise you drag these batteries around for nothing.

Ps. So the graph you show is not representive for the actual situation, which is far better.

To support my story, see the data in this link
https://steinbuch.wordpress.com/2015/01 ... tion-data/

[Andres125sx]

That graph is first I found to ilustrate, I guess they´ve improved it so the curve must be higher now, but the relation DOD/cyclelife still applies wich was my point

Didn´t know Tesla batteries degradation curve is that low btw, thanks for the link

[Brake Horse Power]

I am going to test drive this car soon, in the beginning I tought it was plain ugly but I am starting to like it. Quite unique approach of BMW with a lot of sustainable materials used for production. Like Hemp, sustainable wood finish, recycled plastic etc. You can really see it in the car..
It weighs +-1250kg which is extremely light for a BEV. Effective range about 250km

[hollus]

Hemp???!!! What used to be used to make strings?
Other than the obvious joke... what for? Where?

[Big Tea]

Hemp???!!! What used to be used to make strings?
Other than the obvious joke... what for? Where?

The latest string theory

[3jawchuck]

Hemp???!!! What used to be used to make strings?
Other than the obvious joke... what for? Where?

Probably in plastics that are under minimal strain. It could also be part of the noise insulation. This is not new in the industry and is just good marketing by BMW to highlight something they already use.

[Just_a_fan]

Hemp???!!! What used to be used to make strings?
Other than the obvious joke... what for? Where?

Biocomposites. BMW have been using for some years now in the i3. Others are doing similar.