BEVs deals and information

ABrass

It depends how the manufacturers use the extra capacity. If it's used as a sacrificial or 'grace' capacity that wears out and then the entire remaining storage is available then you'd expect to see zero or virtually zero drop initially and then increasing wear once that is used up as the user would be seeing and using more or all of the available charge.

If it's set up so that, at all times, you can only see and use part of the battery, eg the top 5% and bottom 5% are hidden from you, then that's different. Then the deterioration should be an initial drop at the start and a slower degredation over time but without any sharp drop off.

The latter seems a better approach to me as it's trying to ensure the maximum life of the battery rather than making it look good for the first X years (presumably the warranty period).

almillar

joefizz:

Yeah, its something Im looking into for the home batteries

OK, now we've agreed on SOC, how easily available it is to a home user (<£15 dongle, Android device, <£5 app), can we agree there's not some huge consipracy by the manufacturers to stick in cheap batteries, overclock them to get more performance out of them, and reduce their lifespan?!!

they struggled to get over 96% reported in September and charging from 96 to 99 (topped out) took ages.

What, recently? I'll bet it was in colder conditions than in September. I saw the SOC in Zoe go down in winter, then back up in summer. As you already know, temperature really matters! When using the above apps, they tell you cell temps. If the car (battery) is cold, you go for a wee (spirited) drive, to get them warm. Always test at 15-20 degrees centigrade, otherwise it'll be inaccurate.

JKenH:

The secret of longevity in the EV battery is oversizing and only operating in mid-range with plenty of “grace capacity”

It's not a secret, and yes, this is being taken account of. You get sold a, for example, 22kWh car, which actually has a 24kWh battery. Hard to complain about that really. My first SOH reading on my Zoe was 105%!

Apologies if I have misunderstood

Nope, you've got it.

joefizz

ABrass wrote: »

The latter seems a better approach to me as it's trying to ensure the maximum life of the battery rather than making it look good for the first X years (presumably the warranty period).

Exactly! Finally!

Its why you cant take no apparent degradation over the first say 2 years or x cycles as gospel because a lot of the BMS is doing this all in the background.
Saying car x defies physics because of reported soc is just nonsense when its just good battery management.
It also plays a little to our psyche (freakonomics type) in that the drop only becomes noticeable around the time most cars first change hands (2-3 years).

Its also why you cant use Nicks calculations to say what the installed capacity (vs rated) is and multiply this by x amount to get a battery cost.


The warranties are usually a good guide to the estimated lifecycle, you can get that from the already long published chemistry and battery specifications and work backwards to what you need to install (or see what you can maximally install, see how you need to manage it to reach a series of warranty levels and then pick one).
It will be a fair estimation that the majority of cars/home batteries will be slightly above the warranty at the rates specified, again depending on usage (which is why the warranties have caveats if you look down into them).


Further down the line it will depend on how effective the BMS is and if you can isolate individual cells rather than just modules. Once you get down to the 60-50% range the bms might be on permanently moving things around which again accelerates degradation, also you will have degradation of the cooling/heating medium which means thats less effective etc etc (might well be a service item in the future)

Martyn1981

ABrass wrote: »

It depends how the manufacturers use the extra capacity. If it's used as a sacrificial or 'grace' capacity that wears out and then the entire remaining storage is available then you'd expect to see zero or virtually zero drop initially and then increasing wear once that is used up as the user would be seeing and using more or all of the available charge.

If it's set up so that, at all times, you can only see and use part of the battery, eg the top 5% and bottom 5% are hidden from you, then that's different. Then the deterioration should be an initial drop at the start and a slower degredation over time but without any sharp drop off.

The latter seems a better approach to me as it's trying to ensure the maximum life of the battery rather than making it look good for the first X years (presumably the warranty period).

I suspect Tesla is the later camp, as they've done several over the air 'permissions' (?) to allow folk in areas with hurricanes, wild fires etc, to utilise the whole battery capacity. I assume they dial it back down afterwards.

They've also increased some ranges, and whilst the recent TM3 increase was due to a more efficient motor, I think (may be mis-remembering) that some have been due to them relaxing some of the restrictions on battery use as their data reveals that they are being too cautious.

Putting Tesla aside (hard not to mention them as they are at the cutting edge), it seems to me that all of the news on batteries is typically better than expected, even going as far back as the early Prius HEV's, with the 2nd gen batteries seeming to last forever v's expectations.

joefizz

almillar wrote: »

joefizz:
OK, now we've agreed on SOC, how easily available it is to a home user (<£15 dongle, Android device, <£5 app), can we agree there's not some huge consipracy by the manufacturers to stick in cheap batteries, overclock them to get more performance out of them, and reduce their lifespan?!!

I dont think I'll be able to explain this again but here goes.
Batteries come in a range of chemistries for the form factor, search for the panasonic specs for batteries in the form factors used in teslas for instance, they have about 4 or 5 different chemistries at different power levels, price points and longevity/temperature tolerance specifications.
The cheaper batteries in a range generally have that cost saving at clipping of other characteristics (longevity and being a bit more difficult to manage (the unsafe factor) than others).
If say you find that your bms is managing the batteries better than you expected for warranty then you can in say your next factory use a cheaper spec battery and still meet warranty (or just change warranty for that territory).

As for overclocking, well isnt a term for actions similar to what nissan did with the original leaf battery? Not overclocking as the generic populace would know it but not running it at its optimal on the data sheet to get it to fit other requirements.
Look up battery data. There are like five or 6 points on the star.
Its a bit more complicated than the quality, cost, speed triangle where you get to pick two characteristics, here you get to pick 2 or 3 from 5 or 6.

almillar wrote: »

What, recently? I'll bet it was in colder conditions than in September. I saw the SOC in Zoe go down in winter, then back up in summer. As you already know, temperature really matters! When using the above apps, they tell you cell temps. If the car (battery) is cold, you go for a wee (spirited) drive, to get them warm. Always test at 15-20 degrees centigrade, otherwise it'll be inaccurate.

Which is why I installed it in the spare room at close to optimal temperature and reasonably constant (as temperature swings go). I can also get the humidity down to almost optimal because optimal would mean real problems for humans but I can bump it up when visitors stay.
Its why I would be reluctant to charge it at night as some of the home battery manufacturers only have their 'unlimited' warranty apply to solar charging only and not double cycle per day.

I read the battery specs before purchase ;-)
I would still expect it to reach its warrantied 70% of rated value in 7 years but once it reaches about 60% or 50% then it would be time to start replacing cells as the bms would probably be constantly moving charge around deteriorated cells unless theres an update to the bms to isolate overly depleted cells. (I mentioned this a while ago in the battery thread about costing in cell replacement before the 10 year payback time was up).
It would be realitively easy to replace the cells, if the command line tool shows cell health use that, else take the cells out and put them on my battery meters to find out the current Ah and use the depleted ones for something else. Or if they are cheap enough or have been superceded by replaceable sodium ones by then, do that.

joefizz

GreatApe wrote: »

A 250 mile model 3 even if it lost 30% of its capacity eight years down the line is a very useable 175 mile range BEV

And in 10 years it might be down to 40-50% so still capable of doing 50-70 miles on a charge before the bms melts down and you have to charge again.


As you say (cant believe Im agreeing with GA ;-)) its all useable but to say with any battery powered car capable of 200,000 miles in 2 years (again Ive said, ideal taxi) you can just divide that by x miles per year average to get 200000/x years lifetime isnt correct as time, temperature, bumps in the road, charging patterns, supercharger use etc etc will all have contributed more to the degradation by then than just mileage/cycles alone.


I would hope that given a 5 year development cycle and 5 year application cycle that by the time that comes around we would be making cars will almost fully recyclable/service replaceable batteries (lithium or sodium or fuel cell). Thats of course if we intended to be fully green and not just in the business of selling new cars.....
...which is I think a point Ive probably laboured too much and with the election coming up and more stats to process for that probability I'll leave my part in the discussion on this thread.


Before I go I'll leave you all with 2 discussion points for you all to ponder over the next two months...


1. will EV sales fall in the UK in the next month or two due to labours possible announcement of the scottish ev scheme extended to the rest of the uk (33k interest free loan, removal of 40k luxury tax, 3k diesel scrappage).. (somebody please vote for them as I'd like to see the 25k model three for me (after vat and writing off against tax))
If labour get in will it see sales continue to fall until scheme announced.


2. China EV sales have fallen over a cliff. Down to model 3 pre-orders or a wider phenomenon....

ABrass

That last one doesn't need months of pondering. China BEV sales are rising despite a shrinking market and that their subsidies were halved. PHEV numbers have dropped off a cliff as the subsidies have ended for anything without a long range battery. In any market if the subsidies are cut the sales peak before and drop afterwards. It's not rocket science. That the sales rose despite halving the subsidies for longer range BEVs is pretty impressive.

https://cleantechnica.com/2019/09/29/china-ev-sales-report-baojun-e-series-new-1-in-receding-market/

The market should increase now Giga factory 3 has been given the license to start production. China is half the world's EV market, it is still supply limited for BEVs.

ABrass

Its why you cant take no apparent degradation over the first say 2 years or x cycles as gospel because a lot of the BMS is doing this all in the background.
Saying car x defies physics because of reported soc is just nonsense when its just good battery management.
It also plays a little to our psyche (freakonomics type) in that the drop only becomes noticeable around the time most cars first change hands (2-3 years).

Yes, and that night be the case for some makes, but it isn't for the market leader Tesla as the numbers you have seen show that's not what they do.

The lower volume makes like Audi, Jag and Porche haven't got enough cars on the road yet to prove anything, and Nissan has mixed history with batteries.

Martyn1981

I think we all knew/suspected this, but it's finally official.

Purely 'ponderment' but with ever lower CAPEX and OPEX as Tesla learns, plus (or is it minus?) no import tax (Brexit dependent) then might we see cheaper Teslas from 2021?

It’s Official — Tesla Gigafactory 4 Will Be In (Or Near) Berlin

Musk was in Germany to accept a Golden Steering Wheel award from Auto Bild, a German publication that covers the auto industry. “Berlin is great,” Musk said after the award ceremony. “I love Berlin.” In its latest earnings letter, Tesla said the European Gigafactory would likely be operational by 2021, predicting it would be similar to the Shanghai facility, since both will be manufacturing the Model 3 sedan and Model Y SUV/crossover.

JKenH

Old news but good news about the price of batteries. Almost too good to be true?

https://www.driving.co.uk/car-clinic/driving-green/driving-green-are-pure-electric-cars-suitable/

But last year Nissan quoted a replacement 24kWh battery pack for the Leaf at ‘only’ £4,300, less £1,000 for your old batteries, or as little as £2,000 if you buy a reconditioned one.


It was

https://www.autonews.com/sales/nissan-leaf-buyers-dealers-worry-about-replacing-worn-out-cells