Electric Vehicle: Will you buy one

Forums › Transport (cars, bikes and boats) › Electric Vehicle: Will you buy one - if not why not?

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#1817686 10-Jul-2017 10:34

Geektastic:

When there is one that charges in 5 minutes, does 800km with 5 people and their luggage on board and has the size and ability of a Land Rover Discovery, I shall certainly consider it.

I hope you're still in your 20's because I suspect you won't be needing to consider such an EV anytime soon!

kryptonjohn

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#1817742 10-Jul-2017 11:40

I reckon according to the laws of thermodynamics that hybrids ought to be worse that the same car with the batteries and electric motors etc removed, as long as you are an economical driver that doesn't stomp on the brakes all the time.

All the energy in a hybrid has to come from petrol. Sure it can regenerate power from braking, but that kinetic energy came from petrol originally. But to get to be battery power it has to suffer all the efficiency losses in the chain. Plus hybrids are lugging around all that extra weight.

So basically hybrids can't help you if you are an efficient driver that anticipates/coasts instead of waiting till the last minute and using the brakes.

I now await getting shot down in flames...

MikeAqua

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#1817767 10-Jul-2017 12:11

kryptonjohn:

All the energy in a hybrid has to come from petrol. Sure it can regenerate power from braking, but that kinetic energy came from petrol originally.

Unless it's a plug in hybrid. You might use energy that came from the electricity grid to build up speed that you then recover with the brakes.

Mike

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#1817771 10-Jul-2017 12:16

kryptonjohn:

I reckon according to the laws of thermodynamics that hybrids ought to be worse that the same car with the batteries and electric motors etc removed, as long as you are an economical driver that doesn't stomp on the brakes all the time.

All the energy in a hybrid has to come from petrol. Sure it can regenerate power from braking, but that kinetic energy came from petrol originally. But to get to be battery power it has to suffer all the efficiency losses in the chain. Plus hybrids are lugging around all that extra weight.

So basically hybrids can't help you if you are an efficient driver that anticipates/coasts instead of waiting till the last minute and using the brakes.

I now await getting shot down in flames...

Prius C has only 20 modules (~1kg each) in it's HV Battery with enclosure and relays adding <30Kg.

4.1L/100KM is average actual per the last 4000 kms. Let's say the weight of the driver is ~58-68KG.

There are other drivers -> over 100KG

Some have nothing in their car, others are carrying power tools or musical gear which is heavy.

Some have habit of only having 20L in the tank, while others top up to full if it is 1/2

So weight differs, so it's impact.

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tripper1000

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#1818959 10-Jul-2017 16:15

kryptonjohn:

I reckon according to the laws of thermodynamics that hybrids ought to be worse that the same car with the batteries and electric motors etc removed, as long as you are an economical driver that doesn't stomp on the brakes all the time.

All the energy in a hybrid has to come from petrol. Sure it can regenerate power from braking, but that kinetic energy came from petrol originally. But to get to be battery power it has to suffer all the efficiency losses in the chain. Plus hybrids are lugging around all that extra weight.

So basically hybrids can't help you if you are an efficient driver that anticipates/coasts instead of waiting till the last minute and using the brakes.

I now await getting shot down in flames...

No flames, but 2 points to include in your mental calculations:

1) Petrol/ICE engines are not very efficient across a broad rev range - better economy can be achieved by loading them at an optimum RPM and torque loading - easy to achieve with a generator & battery energy storage arrangement but impossible to achieve with a conventional transmission. Technology such as Miller Cycle, to further improve fuel efficiency, lends it self better to hybrid drive than conventional transmissions.

2) A conventional gear based transmission & drive chain steals a lot of energy through friction, so reducing the number of moving parts & eliminating transmission oil pumps and transmission oil coolers can lead to improved efficiency.

kryptonjohn

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#1818970 10-Jul-2017 16:36

Agreed and that's why PEVs are better. But in the case of a hybrid to get battery power you are still stuck with the running petrol engine driving the car at non optimal settings and all the parasitic losses in the drive train components?

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MikeAqua

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#1818975 10-Jul-2017 16:40

How about a series hybrid - turbine powered generators, battery and electric motors.

Few working parts in a non-thrust turbine.

Plenty of heat ...

Mike

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#1818987 10-Jul-2017 17:11

Works great in nuclear subs!

You can get tiny gas turbines for larger r/c planes - maybe they could run the generator - interesting idea.

ubergeeknz

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#1819530 11-Jul-2017 12:42

MikeAqua:

How about a series hybrid - turbine powered generators, battery and electric motors.

Few working parts in a non-thrust turbine.

Plenty of heat ...

Already being done https://www.wired.com/2016/07/tesla-co-founder-making-electric-garbage-trucks-jet-tech-not/

kryptonjohn

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#1819542 11-Jul-2017 12:59

Making an inexpensive gas turbine will be the key. Garden variety turbines used in helicopters and small turboprop aircraft putting out 400-1000SHP are in the million dollar price range. Even if produced without expensive FAA certification they're really expensive.

kotuku4

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#1819554 11-Jul-2017 13:28

kryptonjohn:

Works great in nuclear subs!

You can get tiny gas turbines for larger r/c planes - maybe they could run the generator - interesting idea.

See Nissan Note E Power, a series Hybrid, electric motor drive and small 1.5 kWh battery, 1.2 litre 3 cylinder petrol generator only.

Similar to a BMW I3 with ranger extender.

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ubergeeknz

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#1819567 11-Jul-2017 13:47

kryptonjohn:

Making an inexpensive gas turbine will be the key. Garden variety turbines used in helicopters and small turboprop aircraft putting out 400-1000SHP are in the million dollar price range. Even if produced without expensive FAA certification they're really expensive.

They already sold a bunch, so I guess it's cost effective enough

KiwiME

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#1819950 11-Jul-2017 22:06

kryptonjohn:

I reckon according to the laws of thermodynamics that hybrids ought to be worse that the same car with the batteries and electric motors etc removed, as long as you are an economical driver that doesn't stomp on the brakes all the time. All the energy in a hybrid has to come from petrol. Sure it can regenerate power from braking, but that kinetic energy came from petrol originally. But to get to be battery power it has to suffer all the efficiency losses in the chain. Plus hybrids are lugging around all that extra weight. So basically hybrids can't help you if you are an efficient driver that anticipates/coasts instead of waiting till the last minute and using the brakes.

Hybrids, particularly the Toyota HSD, are very effective because the load-leveling capability of the battery-backed transmission keeps the engine strictly at its most efficient RPM for all the power levels demanded of road use, including zero and negative (meaning regen.) This also allows Atkinson cycles to be used which improve efficiency at the expense of torque spread (flexibility.)

15+ years of data proves this. Toyota are on their 6th+ generation of HSD design and they keep improving it.

Additionally, the HSD has lower transmission losses at highway speeds where unavoidable aerodynamic drag becomes significant. At around a continuous 100 kph the earlier generations of the Prius had very low losses as very little electric power conversion is required between the two motor/gens. Newer models have minimal losses at even higher speeds.

None of this of course has anything to do with the fundamental "laws of thermodynamics," it's just good engineering.

MarkH67

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#1821283 12-Jul-2017 14:27

6FIEND:2) CO2 emissions to produce an EV battery are extremely high. (equivalent to running a typical petrol/diesel car for over 8yrs in the case of a Tesla Model S) (source) Consider that the usable lifespan of such a battery may only be 5-10yrs.

There is a problem with your source - it is a climate change denier site and cannot be trusted.

MarkH67

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#1821297 12-Jul-2017 15:00

I currently ride a motorcycle and battery electric motorcycles are much more limited in range than BEV cars, if I could get a bike with Tesla-like range I'd be pretty keen. I don't have a car but if I were buying one today I'd definitely want to go with a BEV. If I won lotto then it would be one of my first purchases, with a very big win I'd get an Tesla Model S P100D with ludicrous mode.

For me I see it as unlikely that I'll ever purchase a car that runs on fossil fuels, if I buy a car it will definitely be electric.

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