That's quite a good way of looking at the issue of battery longevity. Imagine that your petrol tank shrank a bit every time you filled up.
But you never know how small any tank has got. So buyers won't risk money buying second hand cars. So sellers have no market, and can't raise any money to offset the cost of a new one.
Sam - second hand value seems to be a major problem with EVs, possibly bigger than range or original purchase price. Essentially buyers are buying a battery with unknown durability which at the moment seems to be unrepairable if it degrades quickly.
dearieme - I don't know why copper is used because it is always liable to be stolen. Aluminium would presumably work because it is used in power transmission lines, but I don't know if there is an issue with using it in EV cables.
Fine stranded copper cable is very flexible and stays so for a very long time. Witness all the flexible cable you have in your home. Also dampness does not corrode copper quickly. Possibly the only equal or better metal would be silver. If there was some material that would do the same job, carry heavy current, cheaply, safely, for a long time it would have been in use by now. Copper is very recyclable. A very large proportion of currently used copper has been used before - way back into history. Maybe in future efficient non contact energy transfer methods will be developed - em microwave or magnetic induction.
The Post Office Telephones tried that when world copper prices went through the roof during the Rhodesia crisis. Unfortunately, it was many years before the brittle nature (compared to copper) became apparent. A lineman opening a joint to make a repair knew that he would almost certainly create more faults by the time he'd finished and re-sealed the joint. The long term costs well exceeded the short term savings...
If I were given this as an undergraduate project I'd try to find something I could add to the copper that wouldn't stop it doing the job but would make it harder to recycle. How about some suitable radioactive metal? Such that a vanful of stolen cables would exceed the critical mass and you'd get a thermal runaway (preferably not an explosion).
@microdave: that's a good objection for what is intended to be permanent wiring. But for a recharging cable that would otherwise be stolen it seems a bit feeble. Even if an aluminium cable lasted only a year it would be dead easy to replace, wouldn't it?
Doonhamer - yes, an efficient non contact energy transfer method seems to be what is required. Leaving expensive cables around has always seemed risky.
Dave - interesting, so no alternative until further developments.
dearieme - maybe the cost of the cable wasn't seen as an issue with the cars being so expensive anyway.
Why is the cable attached to the charging station? Why not tell motorists to bring their own cables and just plug in each end, one to the car, one to the station? Solved!
As Doonhammer has pointed out, copper is very flexible - an important feature for EV charging cables which are being moved around frequently. While aluminium alloys were subsequently developed, which largely solved the "brittleness" problem, it still doesn't alter the fact that copper has a lower electrical resistance. For long telephone lines this means using a thicker conductor (so less pairs in a given duct space). For "Rapid" EV charging (with - potentially - 100's of kilowatts being transferred) it's a much more serious concern.
Personally, I think any system where completely untrained people are expected to deal with high voltage AC (let alone DC) plugs and leads, outside in the rain, is utterly bonkers. If you had suggested this to an electrical engineer 20 or 30 years ago they would be calling for you to be sectioned...
As for theft - aluminium is also eminently recyclable, and has a decent scrap value, so the criminals would still nick it!
Dave - "Personally, I think any system where completely untrained people are expected to deal with high voltage AC (let alone DC) plugs and leads, outside in the rain, is utterly bonkers."
I agree, some of the claims about super new batteries with huge power densities charging in 10 minutes are even worse. They would involve crazy currents and voltages but the blurb doesn't mention that.
13 comments:
That's quite a good way of looking at the issue of battery longevity. Imagine that your petrol tank shrank a bit every time you filled up.
But you never know how small any tank has got. So buyers won't risk money buying second hand cars. So sellers have no market, and can't raise any money to offset the cost of a new one.
This might not take too long...
Why copper? Couldn't they use some sort of carbon fibre instead? Is there any way of using aluminium?
Sam - second hand value seems to be a major problem with EVs, possibly bigger than range or original purchase price. Essentially buyers are buying a battery with unknown durability which at the moment seems to be unrepairable if it degrades quickly.
dearieme - I don't know why copper is used because it is always liable to be stolen. Aluminium would presumably work because it is used in power transmission lines, but I don't know if there is an issue with using it in EV cables.
Fine stranded copper cable is very flexible and stays so for a very long time. Witness all the flexible cable you have in your home. Also dampness does not corrode copper quickly. Possibly the only equal or better metal would be silver.
If there was some material that would do the same job, carry heavy current, cheaply, safely, for a long time it would have been in use by now.
Copper is very recyclable. A very large proportion of currently used copper has been used before - way back into history.
Maybe in future efficient non contact energy transfer methods will be developed - em microwave or magnetic induction.
"Is there any way of using aluminium?"
The Post Office Telephones tried that when world copper prices went through the roof during the Rhodesia crisis. Unfortunately, it was many years before the brittle nature (compared to copper) became apparent. A lineman opening a joint to make a repair knew that he would almost certainly create more faults by the time he'd finished and re-sealed the joint. The long term costs well exceeded the short term savings...
If I were given this as an undergraduate project I'd try to find something I could add to the copper that wouldn't stop it doing the job but would make it harder to recycle. How about some suitable radioactive metal? Such that a vanful of stolen cables would exceed the critical mass and you'd get a thermal runaway (preferably not an explosion).
@microdave: that's a good objection for what is intended to be permanent wiring. But for a recharging cable that would otherwise be stolen it seems a bit feeble. Even if an aluminium cable lasted only a year it would be dead easy to replace, wouldn't it?
Doonhamer - yes, an efficient non contact energy transfer method seems to be what is required. Leaving expensive cables around has always seemed risky.
Dave - interesting, so no alternative until further developments.
dearieme - maybe the cost of the cable wasn't seen as an issue with the cars being so expensive anyway.
Why is the cable attached to the charging station? Why not tell motorists to bring their own cables and just plug in each end, one to the car, one to the station? Solved!
dearieme - I'm not sure about this, but some seem to bring their own cables. Maybe it's a Tesla issue.
As Doonhammer has pointed out, copper is very flexible - an important feature for EV charging cables which are being moved around frequently. While aluminium alloys were subsequently developed, which largely solved the "brittleness" problem, it still doesn't alter the fact that copper has a lower electrical resistance. For long telephone lines this means using a thicker conductor (so less pairs in a given duct space). For "Rapid" EV charging (with - potentially - 100's of kilowatts being transferred) it's a much more serious concern.
Personally, I think any system where completely untrained people are expected to deal with high voltage AC (let alone DC) plugs and leads, outside in the rain, is utterly bonkers. If you had suggested this to an electrical engineer 20 or 30 years ago they would be calling for you to be sectioned...
As for theft - aluminium is also eminently recyclable, and has a decent scrap value, so the criminals would still nick it!
Dave - "Personally, I think any system where completely untrained people are expected to deal with high voltage AC (let alone DC) plugs and leads, outside in the rain, is utterly bonkers."
I agree, some of the claims about super new batteries with huge power densities charging in 10 minutes are even worse. They would involve crazy currents and voltages but the blurb doesn't mention that.
You write as if electrocuting the sort of poltroons who buy EVs is bad thing.
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