BEVs deals and information

JKenH

I have absolutely no experience or technical knowledge of Ev batteries but a quick google search revealed this paper
https://www.vehicular.isy.liu.se/Publications/MSc/16_EX_5015_OJ.pdf

A model for Li-Ion battery cells and packs of cells that takes degradation into account has been developed. The degradation is a function of usage and time, referred to as cycle ageing and calendar ageing respectively.

ABrass

JKenH wrote: »

I have absolutely no experience or technical knowledge of Ev batteries but a quick google search revealed this paper
https://www.vehicular.isy.liu.se/Publications/MSc/16_EX_5015_OJ.pdf

A model for Li-Ion battery cells and packs of cells that takes degradation into account has been developed. The degradation is a function of usage and time, referred to as cycle ageing and calendar ageing respectively.

Interesting read. I skimmed most of it and read through the relevant bits. One quote said that over longer periods the calendar effect decreases (you might lose 0.08% over the first year but less in year 2, etc.) whilst the charge effect increases. Or in other words it fails to support Joe's hypothesis. It emphatically does not show the rapid drop off he talks about, but Joe might have another source.

The e↵ects of cycling losses and calendar losses for
long periods of time can be summarized as cycling losses will increase during the
lifetime of a cell and calendar losses will decrease with time.

Martyn1981

joefizz wrote: »

Martyn, agree we are going round in circles.
Battery degradation is a function of time (amongst other things). Its a rapid drop off after a certain period and accelerates after a certain percentage useful. (becomes difficult to manage below a certain percentage).
You can do 200k in 2 years no problem but thats not an indication you can do 200k over 15 years.

We've said our bits so lets revisit in 5-8 years time and see what percentage of the current EVs are still on the road.

Tesla S's have been around for 5-8 years and aren't showing the degradation rates you are claiming even after 200k miles, so I don't think what you are saying, claiming is true. And the TM3 batts are performing better, as would be expected with progress.

Edit - and your time claim seems to be false too, since the recent TM3 data, and the older TMS data (I think Ben Sullins of Teslanomics compiled it) show the opposite, with a swift drop of a few percent near the start, before a reduction (slowing) in the amount of degradation over time/miles going forward (or in reverse ;-)).

almillar

joefizz:

Time will tell but its a gamble now to save money now and maybe pay for it later 6,7, 8 years down the line (or never).
Thats a normal business cost reduction exercise, everyone does it

It's perfectly normal? Why are you talking about it as if it's some kind of scandal then? And again, within the (generous, IMO) warranty period/mileage, that risk is one the manufacturer takes, not the consumer. You've also provided no sources for anything you say above.

So its not really like for like comparing delivered kwh with published cost per kwh produced and using that for price comparions. The cheaper batteries need more cooling and management and more of them to deliver the "same" or nominal power output. This isnt an issue and wont become one until someone tries to get stupid ranges out of a normal form factor car (unless theres a jump in battery technology)

.

How much weight does it add? How much further does a car go? Tell you what, if a car gets a reputation for not going as far as it's meant to, or for its batteries degrading quickly, consumers will know, because many of them are on forums, and can plug in OBD devices to find out!

Where that particular bit gets interesting is that its the SOC being used. Thats only one thing that will degrade with time,the charging capability also will as will the discharge and it will also take the bms longer to manage charge which may lead to issues with the ones that will end up overly relying on this for safety

So you're saying that when a car gets to 70% of SOC, it will not go 70% as far as when it was at 100% SOC, and will also take longer to charge?

Its the posts that expect fast charging for most charges and the car to last 8 years that go against the published data (and probably the warranty t+cs as well - depending on manufacturer)

This seems to be out of date. VW used to have 'no more than 3 rapid charges in a row' in their warranty - I beleieve that's now been removed. Ask yourself why? Either VW is happy to replace battery packs, or it just doesn't hurt as much as they thought, or people just don't do it often enough for it to be a problem.

Does anyone here know anyone that ONLY charges rapidly? My Zoe was almost exclusively charged at 22kW - that's pretty fast, and at 18k miles there's no significant degredation.

Does that make any more sense? Im not anti EV, its just, well, complicated..

Yes it does, thank you. I just don't agree that it needs to be as complicated as above for the consumer.... within the warranty period.

Where it would get dodgy is if close to warranty ages (in another couple of years) software updates misrepresent soc or have the soc value as floating per available

If they remove some buffer, that wasn't ever available as range, from the top (not the bottom) of capacity, that would be fine. But if, for example, Renault updated the Zoe's BMS to say that 20kWh was 100%, whereas previously it was 22kWh, that's just theft, consumers would know, and would reject it. They would NOT get away with it with the user forums. And there's been no evidence that anyone will try.

Battery degradation is a function of time (amongst other things). Its a rapid drop off after a certain period and accelerates after a certain percentage useful. (becomes difficult to manage below a certain percentage).

From anything I've heard, it dips at the start and levels out, like a 'dog tail' graph. Certainly not rapid. Are you confusing degredation with failure?

ABrass

22kw charge rate shouldn't be described as fast anymore. 50kw maybe but I'd hold out for 100kw as a minimum to be classed as 'fast'.

There are a few car services that charge almost exclusively with fast chargers. Tesloop for one. https://cleantechnica.com/2018/07/17/tesloop-shares-lessons-learned-in-400000-miles-in-a-tesla/

As a summary, there's a car service that thrashes the living daylights out of some model S and X's. The earlier models have needed batteries or drive units replaced but the more recent ones seem more reliable and it was all covered by warranty. The cooling system for the model S and X is decent but not in the same ballpark as the Model 3. I'm expecting it to be revamped as part of the work to support the plaid version next year.

joefizz

ABrass wrote: »

Source? The information I can find points almost entirely at use rather than any passive degredation. How much should we expect over time with minimal use? Without a source it sounds like FUD.

Battery lab, ORNL.

ABrass

joefizz wrote: »

Battery lab, ORNL.

Well it's a place. Do you have anything more than that or is this second hand conversation which can't be verified in any way?

JKenH

ABrass wrote: »

Well it's a place. Do you have anything more than that or is this second hand conversation which can't be verified in any way?

This argument seems to be less about calendar degradation and more that Joe has not provided proof in the required format. Hardly necessary I would suggest as anybody who has a look on google will find there is less doubt about calendar degradation than there is about the existence of AGW.

For those who can’t use google here is a link to a page listing numerous articles thrown up by a simple search for “ev battery calendar degradation”.

https://www.google.com/search?rlz=1C9BKJA_enGB711GB711&hl=en-GB&sxsrf=ACYBGNRmr268MVqIvqV45io8-T-a4wPR8g%3A1573499584132&ei=wLLJXb_WB7iX1fAPjcyiyAM&q=ev+battery+calendar+degradation&oq=ev+battery+calendar+degradation&gs_l=mobile-gws-wiz-serp.12..33i22i29i30l2.17959.31475..36011...0.0..0.240.3373.13j18j1......0....1.........30i10j33i10j33i10i21j33i21j33i10i160j33i160.wOvrxmdFUQc

ABrass

JKenH wrote: »

This argument seems to be less about calendar degradation and more that Joe has not provided proof in the required format. Hardly necessary I would suggest as anybody who has a look on google will find there is less doubt about calendar degradation than there is about the existence of AGW.

For those who can’t use google here is a link to a page listing numerous articles thrown up by a simple search for “ev battery calendar degradation”.

https://www.google.com/search?rlz=1C9BKJA_enGB711GB711&hl=en-GB&sxsrf=ACYBGNRmr268MVqIvqV45io8-T-a4wPR8g%3A1573499584132&ei=wLLJXb_WB7iX1fAPjcyiyAM&q=ev+battery+calendar+degradation&oq=ev+battery+calendar+degradation&gs_l=mobile-gws-wiz-serp.12..33i22i29i30l2.17959.31475..36011...0.0..0.240.3373.13j18j1......0....1.........30i10j33i10j33i10i21j33i21j33i10i160j33i160.wOvrxmdFUQc

Nope, my point is that Joe's wrong. He claimed that calendar aging increases dramatically over time when the reverse is true, it tapers off over time. You helpfully found a source that agreed with me, and your Google link take you to multiple other sources that support it.

Joe might have been aware of more sources that contradicted yours, but it seems he has word of mouth and that's it.

Now if you think Joe is right, your examples are wrong, and I've missed something then please chip in.

1961Nick

Just to add a bit of balance...

Many of the current crop of EU6 diesels will be lucky to see 100,000 miles. Blocked DPFs, gummed up EGRVs, ingested swirl flaps, oil dilution, broken cranks, worn turbo bearings ... the list goes on. The cost of fixing these problems at 100,000 miles can easily make the vehicle an economic write off.

The 100K mile EV is starting to look like the sensible choice!:eek: