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happyfunball
282 posts

Ultimate Geek


  #1958111 14-Feb-2018 15:47
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Linuxluver:You'll take a bus when a thousand Ubers can't get you there within an hour of when you'd like to get there. 

Cars just do not scale. It's a physics thing. They take up a lot of space. 

 

 

Sure, but they take up less space because they can more closely follow the autonomous car ahead, meaning more cars fit.  You also have faster traffic flow, since there are less bad drivers and people hunting for parking, less excessive braking, less cutting in etc.  So more cars on the same road moving faster.  Now take away the parked cars on the side of the road, and you have another lane, and now share the bus lane, because the autonomous cars will move out of the way for a higher priority vehicle.  Maybe more people in the car means higher priority so you go faster. You can even charge for priority status, so pay more, get there faster.

 

So many paradigms will change, its probably impossible to predict.  But to think its will be the same as now, with mostly empty bus lanes and a crawling mass of single dudes driving SUV's packed in to the other lanes, seems like a stretch.

 

 


happyfunball
282 posts

Ultimate Geek


  #1958114 14-Feb-2018 16:00
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MikeAqua:

 

I understand that a generator is just motor in reverse, but how does extra draw from the generator make it require more force to turn?  Does it increase the strength of the magnetic field, making the rotor harder to turn?

 

 

Turning it faster requires more force, since you have to overcome the magnetic field more frequently as RPM goes up.  So the faster your wheels are spinning, the more electrical force will be generated, and the more the wheels will slow down.


 
 
 
 


MikeAqua
6058 posts

Uber Geek


  #1958115 14-Feb-2018 16:01
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Linuxluver:

 

happyfunball:

 

Buses are used by people because they are cheaper.  When it costs the same to take an autonomous Taxi, who would take a bus?

 

...

 



You'll take a bus when a thousand Ubers can't get you there within an hour of when you'd like to get there. 

 

As an example ...

 

A bus from WLG to town is $7.20.  A taxi to within a block of the same point is about $30. The taxi actually takes longer during peak times.

 

As a result I always take the bus when travelling alone if time allows.

 

No idea what using Uber would cost.  But Uber pays WLG a $3 pick up/drop off fee and charges this to the customer. 

 

https://www.uber.com/en-NZ/drive/wellington/airports/wellington-airport/





Mike


happyfunball
282 posts

Ultimate Geek


  #1958130 14-Feb-2018 16:29
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MikeAqua:

 

A bus from WLG to town is $7.20.  A taxi to within a block of the same point is about $30. The taxi actually takes longer during peak times.

 

As a result I always take the bus when travelling alone if time allows.

 

 

I was referring to the future when most/all cars/buses/vehicles/helicopters are self-driving and the transport situation is vastly different.  Certainly today the bus makes sense in many cases, as do bus lanes.  Thats why we have buses and bus lanes. This was true 20 years ago and 40 years ago too. Maybe not true 20 years from now.


wellygary
4999 posts

Uber Geek


  #1958139 14-Feb-2018 16:47
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happyfunball:

 

I was referring to the future when most/all cars/buses/vehicles/helicopters are self-driving and the transport situation is vastly different.  Certainly today the bus makes sense in many cases, as do bus lanes.  Thats why we have buses and bus lanes. This was true 20 years ago and 40 years ago too. Maybe not true 20 years from now.

 

To be honest, trying to predict what will happen in 20 years is a mugs game,

 

posit 20 years ago 1988, Google had one employee and still asked you if you wanted to run your search on AltaVista,  the V90 modem standard was agreed to, no one had dreamt of mass market internet connected mobile phones...

 

 


Aredwood
3885 posts

Uber Geek


  #1958194 14-Feb-2018 18:05
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MikeAqua:

Aredwood:


Short answer - yes.


As you know - electricity is needed to recharge a battery. And if you get that power from a generator (which can be an electric motor running in reverse). If you try to increase the amount of power that you draw from a generator, the amount of twisting force (torque) required to keep it spinning at the same speed increases ...


So in an electric car, regenerative braking is simply varying the electrical load on the generator (traction motor being used in reverse) based on how hard the driver is pressing the brake pedal. When the torque required to maintain the generator at a constant RPM, is higher than the contribution of gravity (due to the car going downhill). The generator starts to slow down (car goes slower).



But how does it become more difficult to turn a generator with increased current draw. I guess this question is the reverse of how does a motor draw more power under increased load.


Is it to do with a change in the EM field(s) or something like that?


 



@MikeAqua in a car alternator, it has a field coil which is spun by the engine. And stator coils which generate electricity and stay still. The voltage regulator circuit varies the amount of current flowing through the field coil, to vary the amount of power generated. Typically the voltage regulator just maintains a stable output voltage, even with varying engine speed and electrical load.

The alternator in my van only uses approx 4A of field current at max field drive, but it can generate over 100A.

If you are interested in the deep science of how generators work, have a look at the Wikipedia articles. Google brushless dc motor (type of motor used in almost all EVs) and Series wound DC motor (type of motor used in starter motors) As some good starting points. The science of electric motors and generators is very old and well understood. So Wikipedia will be fine for that research.





frednz
1434 posts

Uber Geek


  #1958315 14-Feb-2018 20:47
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https://www.tvnz.co.nz/one-news/new-zealand/genesis-energy-which-owns-huntly-coal-plant-go-free-2030

 

Chairwoman Jenny Shipley says that by 2025 Genesis has committed to not use any coal to generate electricity in normal market conditions and aims to phase it out completely by 2030.

 

The company had planned to wind up the coal-fired units at the Huntly power station by the end of 2018, but extended their life for another four years in 2016.

 

This is disappointing because, with the growing numbers of EVs, this will lead to greater electricity demand and possibly the use of more coal to generate this energy. Perhaps one way of stopping this is to ban the mining and sale of coal. But President Trump said recently that:

 

"We have ended the war on American energy — and we have ended the war on beautiful clean coal. We are now very proudly an exporter of energy to the world."


 
 
 
 


MikeAqua
6058 posts

Uber Geek


  #1958633 15-Feb-2018 14:50
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happyfunball:

 

I was referring to the future when most/all cars/buses/vehicles/helicopters are self-driving and the transport situation is vastly different.  Certainly today the bus makes sense in many cases, as do bus lanes.  Thats why we have buses and bus lanes. This was true 20 years ago and 40 years ago too. Maybe not true 20 years from now.

 

 

But why do you think that self drive will be cheaper?

 

The case for autonomous cars is not necessarily lower cost (compared to a driver operated EV).

 

Generally more tech = more $$$. 

 

Cars (as linuxlover pointed out) have low passengers per metre of road.  Autonomous EVs could be made smaller and drive closer together (maybe).  But it's hard to see them replacing mass transit. Even if you halved the size of cars and string them bumper to bumper in two columns, they still hold fewer people than a double deck bus of the same length.

 

Autonomous buses - I can see them working nicely.





Mike


MarkH67
401 posts

Ultimate Geek


  #1958653 15-Feb-2018 15:39
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MikeAqua:

 

But why do you think that self drive will be cheaper?

 

 

I would presume we are talking about a self-driving Uber (or similar).  Currently, with Uber, you are paying for the car & driver to take you where you want to go.  With an autonomous car you could pay for the car to take you where you want to go without having to pay a driver for their time, therefore it most definitely will be MUCH cheaper.  Taxi & Uber drivers will need to find new jobs though.


tripper1000
1248 posts

Uber Geek


  #1959004 16-Feb-2018 10:38
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MikeAqua:

 

But why do you think that self drive will be cheaper?

 

The case for autonomous cars is not necessarily lower cost (compared to a driver operated EV).

 

 

Short story: Autonomous cars, while more expensive, greatly improve the practicality of communal ownership (you book a car and it comes to you), dividing the cost of ownership over a group of people, making it cheaper.

 

Longer story: Aside from the autonomous technology making group ownership possible, peoples changing car buying habits overseas is creating the conditions and attitudes needed to make this work. Private citizens are increasing leasing cars in the UK and USA. Leases where you pay for Km's used, rather than the number of years you have the car, exist. Traditional 1 owner-1 driver cars have very low utilisation - 90% of cars are parked up 90% of the time, so companies leasing the cars can reduce costs (and making driving cheaper for customers) by using autonomous technology to share the cars around and increasing the utilisation ratio - ie have fewer cars than customers and get the car utilisation up to 20%, 30%, or 60%.

 

A whole lot of other attractive benefits fall out of this such as: You don't need to have a parking space at home for "your" car any more. You don't have to worry about paying for parking while you are working/shopping etc. You don't have to worry about recharging/refuelling "your" car - it always arrives with sufficient charge/fuel for your journey. Ride sharing becomes more practical - a computer takes care of that and you can 1/2 or 1/4 the cost of your commute (less cars on the road). In the future when the technology has matured, you won't need a driving license to use a car - licencing rates are already plummeting in NZ.

 

The rising popularity of Uber and it's booking system and relatively low cost, kind of reinforces the above concepts. It might be that Uber (so such companies) end up owning all the cars on the road - who knows.

 

Communal ownership/leasing is making the future of EV's look more certain because Lease companies will favour EV's due to the interval between servicing being much, much, longer.


happyfunball
282 posts

Ultimate Geek


  #1959401 16-Feb-2018 23:48
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MikeAqua:

 

But why do you think that self drive will be cheaper?

 

 

Because you don't have to own them.  You can just summon a super-cheap autonomous Uber anytime you need a car.   You can also share the Uber with other passengers, so its like an efficient bus.  Instead of standing at a generic bus stop, the Uber bus comes to your house and stops at your work.

 

 

 

 


Dinga96
101 posts

Master Geek


  #1959654 17-Feb-2018 17:58
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happyfunball:

 

MikeAqua:

 

But why do you think that self drive will be cheaper?

 

 

Because you don't have to own them.  You can just summon a super-cheap autonomous Uber anytime you need a car.You can also share the Uber with other passengers, so its like an efficient bus.Instead of standing at a generic bus stop, the Uber bus comes to your house and stops at your work.

 

 

 

 

 

 

I think the whole idea has potential to solve traffic congestion. It will take some time to solve all the problems of bringing in a new technology. I personally would not use it. It may solve some problems but is not the whole solution and indeed may eventually fade away. I see Uber did not make any money last financial year.Its not quiet time to break out the champagne yet fellas.


kiwirock
653 posts

Ultimate Geek


  #1959657 17-Feb-2018 18:11
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happyfunball:

 

MikeAqua:

 

But why do you think that self drive will be cheaper?

 

 

Because you don't have to own them.  You can just summon a super-cheap autonomous Uber anytime you need a car.   You can also share the Uber with other passengers, so its like an efficient bus.  Instead of standing at a generic bus stop, the Uber bus comes to your house and stops at your work.

 

 

 

 

And who keeps check on the hygiene of these vehicles you never own all day? No thanks! I'd rather take my car to buy food than a vehicle someone else has been sneezing in or has poor hygiene borrowing.


PhantomNVD
2621 posts

Uber Geek
Inactive user


  #1959728 17-Feb-2018 21:13
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Back to EV discussion please?

A while back we were discussing the possibility of a ‘range extender ‘ trailer... here’s an interesting option I just came across on YouTube... up to 50KW of battery and 1.2KW solar to charge it too !

https://youtu.be/34NwCEQtC1Y

PhantomNVD
2621 posts

Uber Geek
Inactive user


  #1959759 17-Feb-2018 23:57
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And Christchurch just launched their 100 EV carshare servive via yoogo:

https://www.driven.co.nz/news/news/southern-hemisphere-s-largest-ev-car-sharing-scheme-launched/

$15/h to drive a BMW i3? Yes please!

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