bpg
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Post by bpg on Mar 30, 2024 23:51:36 GMT
>> That's like saying let's drain all the oil out of your petrol engine, run it with no oil, and see what happens when the manual tells you don't run it with the oil pressure light on. Not quite. Running it below 20% every now again should be okay otherwise the car should have a default safety level and not allow you to use it. If it is not possible without damage then don't allow it.Spoken like a software engineer. You can't do that, it is a car it has to move, you do not know the circumstances under which the person is operating the car. You're stuck on a railway crossing and computer says no is not an acceptable scenario. If the car can move it should regardless of the damage it may do to the internals. No oil in your car does not stop your from starting the engine and driving. Back to the question of why run it flat? The manufacturer quotes a max range which includes 0-100% battery. New it will be greater than pre-owned. So to show how they have degraded needs such a test surely? It's not as if they are doing to all the time. Just seeing how far it can really go, i.e. max range. The manufacturer also quotes a maximum speed and a 0-100kph or 0-60mph time, that also declines over the life of the vehicle and is an indicator of the wear and tear on the drive train irrespective of the fuel. Stressing the battery every time the vehicle is sold or tested is unnecessary. Every time the car is charged it gives an indication of how far it can go and that is pretty accurate because it knows how far it has travelled on the last charge and uses that to display how far it can go a bit like the distance to empty on a fossil fuel car. If you see an EV showing only say 75% or less of what you expect from reading the manufacturer data then you question it and if you do not like the answer walk away bearing in mind the season. Edit: On the other hand is there another vehicle that gets abused in the same way as a diesel at MOT time ? Holding cars at the rev limiter multiple times and if the cambelt or timing chain breaks tough luck. Maybe they should also hold petrol cars at the rev limiter in a similar way and fast discharge an EV battery then fast charge it multiple times. |
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Rob
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Post by Rob on Mar 31, 2024 0:49:49 GMT
This thread is now getting stupid. If an EV cannot use the last 20% except in emergencies. And it cannot use the top end 20% at all. Then the battery has only a useable capacity of 60%. So quote a range based on that. Problem solved. So quote a real world range say for a 77kW battery based on 56.2kW. Anything more is a lie then?
So for my car... it's about 62 litre capacity. How much of the liquid capacity is safe to use? Because people are comparing range. Should I limit myself to 37.2l because of the dangers of overfilling or running low?
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bpg
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Post by bpg on Mar 31, 2024 1:00:30 GMT
Most people refuel when the light goes on at the latest, no one uses 100% of the petrol or diesel tank capacity. When was the last time you stopped and put 62 litres of fuel in your car ? No one says you can't use the top 20% of battery capacity however repeated DC fast charging does degrade the performance of the battery. AC charging will not overheat the batteries in the same way so if you want to use that last 20% load them slowly and maintain the performance of the battery pack.
That top 20% of the battery pack is like red lining a fossil fuel vehicle from cold. If you have any mechanical sympathy or care for your wallet you warm the engine up, specifically the oil, before using the full available performance.
Edit: When you refuel do you always fill the tank ? With my diesel I run it down to around 100 miles to empty (the light comes on at about 80 miles) and I put 35 litres in, about half a tank, takes it back up to about 2/3rds full. Unless I have a long distance journey I do not fill the tank. My petrol on the other hand I fill because it has such a low range, about 250-300 miles on a full tank, that only represents about 75% usage though as I don't coast into the fuel station on vapours.
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Post by EspadaIII on Mar 31, 2024 6:31:51 GMT
Fast DC charging on my car, and I suspect many others, slows down significantly after it reaches 80%. Say it is charging at 120kW, at 80% it will slow down and by 90% it is pushing well under 30kW. The 10% is pretty much at AC speeds if not slower.
I have set my car to 80% on DC but maintain 100% on AC. I rarely get to 100% as I only charge at home for five hours (cheap rate) so if I plug in below 50% I cannot reach 100%.
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Rob
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Post by Rob on Mar 31, 2024 16:13:14 GMT
When I refuel I always fill to full. How low it has got depends on what I've been doing and the next journey. So like this week it was down to a quarter of a tank and I had to do over 330 miles to get to the destination. So I filled it. Then it needed filling to get home. So it was refilled. It is now down to just under 1/4 tank so it will be refilled to full again this week.
In the Skoda I did deliberately see how far it would go and drove it beyond when the filler light came on. I filled it until the pump clicked off. It did a great range on that tank but then when refilled it took 5 litres more than the tank holds so some is in the filler hose. And it had at least 4 litres still in it.
If i got a small electric car, it would have aa small battery capacity so I'd probably not bother with a 7kW charger even apart from thinking of the safety aspect. If on a slow charge it is safe to use the full 100% then I'd hope you could.
But can you be sure a second hand EV hasn't been used as say a company car. Clue might be in the high mileage on a young car. And therefore rapid charging and maybe to 100% often is a risk.
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Post by EspadaIII on Mar 31, 2024 18:48:24 GMT
As I have reported previously, E350 CDi did 722 miles on one tank and I chickened out as I was far from home. Assuming all EVs have some form of battery protection I wonder what the difference in battery condition is after say three years and 36,000 miles between two cars, one of which was mostly charged overnight at 7kW and the other that used mostly fast charging...
In November 2021 I met a guy at Abington Services (J13 M74), driving a Hyundai Kona electric. He drove long distances as a courier for some medical procedures (not blood but something that required fairly urgent deliveries). He charged at the maximum of 50kW and did several hundred miles each time he did a job and I think he said he did many tens of thousands of miles each year. The day I met him he had done Dundee to Glasgow, Glasgow to Liverpool and was on his way home. I reckon that is over 600 miles. I wonder how that car is now?
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Rob
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Post by Rob on Mar 31, 2024 20:48:20 GMT
I wonder how well or not EVs manage their batteries which consist of multiple 'packs' with many cells. The original Teslas had many thousands of the 18650 cells. I know larger cells has reduced the number of individual cells.
Rapid DC charging aside, with nominal battery sizes quoted as smaller than the actual, I'd assumed there was some sort of management of the cells used over time to increase overall life of the battery packs and reduce the impact of faulty cells.
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Rob
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Post by Rob on Mar 31, 2024 20:49:30 GMT
The clue to how the batteries fare over time is the warranty limits. An ICE of similar age would also have limits but the cost to sort out an ICE would be less than replacing a battery pack.
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Post by EspadaIII on Apr 1, 2024 10:12:34 GMT
Several years ago an Israaeli with the co-operation of Renault invented the Better Place company which was a fairly normal EV saloon but with swappable batteries, which you did at the equivalent of a petrol station and the whole process took five minutes.
The company was about five years ahead of its time and I think the idea is being revived; the main problem being that batteries are not a standard size or shape. Imagine if there was some way of making this work; battery packs could be checked each time it was swapped out for condition and percentage of maximum initial power and the price paid could reflect the reduction in performance of the pack since you loaded it on to your car.
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bpg
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Post by bpg on Apr 1, 2024 12:49:57 GMT
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Post by EspadaIII on Apr 1, 2024 15:35:35 GMT
It would solve range anxiety at a stroke. Repurpose filling stations, cheaper to build, can install in city centres where petrol stations are rare.
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WDB
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Post by WDB on Apr 1, 2024 18:00:16 GMT
I used to be an advocate of this but I’m no longer convinced. Standards — or the lack of them — are one problem, but I think the bigger one is that in the seven years or so since it seemed a clever idea, BEVs and their charging networks have become mainstream. Motorway rapid charging is now generally reliable — although expensive because of the need to recoup infrastructure investment.
Battery exchange would rely on the same grid but with a new layer of infrastructure to develop and pay for, plus a whole new set of vehicles seeking to make the established technology obsolete. The used EV market has already been disrupted by several rounds of regulatory hokey-cokey, to the detriment of adoption and the environmental improvement that depends on it. Better now to focus on fixing the imperfections in what we have than to keep butterflying after the next bright idea and never actually improving anything.
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Rob
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Post by Rob on Apr 3, 2024 17:59:05 GMT
Back to the Audi e-tron.... I said in this and other threads how cheap some EVs seem for what you get. The e-tron for example seems cheap but then you're taking a gamble with the batteries to a certain extent, with an educated guess on a fair bit of rapid DC charging to get that mileage too young.
But looking on Auto Trader, the cheapest 3.0l diesel Audi Q8 on a 20 plate is £36.5k at around say 76,000 miles. The cheapest Audi e-tron of similar age is £19k and 70,000 mils on a 70 plate. Nearly half price but the e-tron was more expensive when new.
There's actually one e-tron cheaper but higher mileage so I ignored and use the example at an Arnold Clark dealers. The mileage is flagged as being over 40k miles above average. And the range is less than 200 miles... the Q8 3.0 TDI will probably go 4 times further on a full tank.
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bpg
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Post by bpg on Apr 3, 2024 18:10:16 GMT
I used to be an advocate of this but I’m no longer convinced. Standards — or the lack of them — are one problem, but I think the bigger one is that in the seven years or so since it seemed a clever idea, BEVs and their charging networks have become mainstream. Motorway rapid charging is now generally reliable — although expensive because of the need to recoup infrastructure investment. Battery exchange would rely on the same grid but with a new layer of infrastructure to develop and pay for, plus a whole new set of vehicles seeking to make the established technology obsolete. The used EV market has already been disrupted by several rounds of regulatory hokey-cokey, to the detriment of adoption and the environmental improvement that depends on it. Better now to focus on fixing the imperfections in what we have than to keep butterflying after the next bright idea and never actually improving anything. I read about this in China, indeed standardisation is the issue as there are so many EVs the manufacturers do not see the need to do anything than please themselves and lock the consumer into 'their product'. Back to the Audi e-tron.... I said in this and other threads how cheap some EVs seem for what you get. The e-tron for example seems cheap but then you're taking a gamble with the batteries to a certain extent, with an educated guess on a fair bit of rapid DC charging to get that mileage too young. But looking on Auto Trader, the cheapest 3.0l diesel Audi Q8 on a 20 plate is £36.5k at around say 76,000 miles. The cheapest Audi e-tron of similar age is £19k and 70,000 mils on a 70 plate. Nearly half price but the e-tron was more expensive when new. There's actually one e-tron cheaper but higher mileage so I ignored and use the example at an Arnold Clark dealers. The e-tron will be cheaper for the business which purchased it as the full price can be written off against taxes. The diesel will not be the case and, to the business which funded it, be more expensive. Without knowing if it was a business or private purchase you can't say which was more expensive. What it does mean is these executive brands to the private buyer are an excellent used purchase at 2 years but horrible on the bank balance new. |
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Rob
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Post by Rob on Apr 3, 2024 18:33:35 GMT
But these good deals have me wondering... what am I missing. Also how was it okay for Audi to have a car as large as the e-tron only capable of up to say 200 miles.
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