EV mode - can anyone help please?

[Jocko]

I assume all modern cars with some form of electrical drive can direct regenerated power back to the battery.

As far as I am aware, that is the case.

[Expatman]

We are in the early stages of battery development for EV’s, currently batteries are heavy and can only be charged relatively slowly. There was an article recently describing a new battery technology that allows a battery to be charged in a few minutes, I would think that over the next few years the science will develop quickly and within ten years we could have EV’s offering 400 mile real range and, more importantly, recharging in a few minutes. Where all the electric supply is going to come from is another question altogether!
There are also hydrogen powered fuel cells which could be an answer as well.
The next ten years is going to be an exciting time for both the motor industry and for motorists.

[Downsizer]

I heard a lecture yesterday by a hydrogen expert who reckons fuel cells will be best suited to buses, trucks and trains on non-electrified lines, leaving lighter vehicles powered by rechargeable batteries.  It is more efficient to use electricity directly rather than using it to separate hydrogen for fuel cells, as there are always losses in conversion.

[John Ratsey]

currently batteries are heavy

Lithium batteries are lightweight compared to the lead and nickel batteries! However, the researchers are trying to further improve the charge capacity. What's more relevant is how much of the size and weight of a vehicle's battery pack is actually battery? The Tesla Powerwall domestic battery has 13.5kWh usuable capacity and weighs 125kg https://www.tesla.com/sites/default/files/pdfs/powerwall/Powerwall%202_AC_Datasheet_en_GB.pdf which equates to about 10kg/kWh capacity and includes a modest heating/cooling system appropriate to the 5kW rating. In vehicles the higher power rating results in a much greater cooling requirement as heat degrades the chemistry.

The Mk 4 Jazz would, overall, be slightly more efficient if there was more energy storage capacity although I wonder if a super-capacitor would be the best way to achieve this. First, however, Honda need to address the cold weather operation problem which has a much bigger impact on the real life fuel economy although it doesn't show up in the official testing due to failure to include a low temperature sequence in the test cycles.

I heard a lecture yesterday by a hydrogen expert who reckons fuel cells will be best suited to buses, trucks and trains on non-electrified lines, leaving lighter vehicles powered by rechargeable batteries.  It is more efficient to use electricity directly rather than using it to separate hydrogen for fuel cells, as there are always losses in conversion.

He's correct when considering the automotive power in isolation. However,  when combined with the problem of how to balance the variable supply of renewable energy with the more predictable demand then hydrogen appears to have a place in the mix. I also see a place for a small fuel cell working alongside a medium-sized battery. Size the fuel cell for constant output and let the battery handle the variation in power requirements (a logical progression of the current hybrid systems).

[Expatman]

You are right about the low temperature performance of the Jazz, however, it is difficult to see what they can do to radically improve fuel consumption. Assuming that passengers demand heat (I do) then that heat can either come from the ICE running or from a heat exchange unit - basically A/C running in reverse. Running the ICE inevitably consumes fuel but running a heat exchange unit would require significant electric power - and that can only come from running the ICE to charge the battery. I assume the same would happen in a hot climate in summer where the A/C would need to run constantly to cool the cabin but perhaps the power requirement to warm the cabin on a cold day exceeds the power requirement to cool the cabin on a hot day?
Anyone with any detailed knowledge of the technology of this?

[embee]

The wider topic of how to power personal transport (cars) is intricate and has numerous variables, as I'm sure has been discussed here. The two principal issues which are simplest to consider are the toxic emissions ("regulated pollutants" i.e. CO, HC, NOx, particulates) and the CO2 emissions (technically CO2 is not a "regulated" pollutant as far as cars are concerned).

For toxic emissions in cities, it's a no brainer. Use EV and keep the air less dangerous to breathe.

For CO2 it's a far more complex issue. If a country can produce a large percentage of its electricity from clean renewables it's a relatively simple assessment. If not, then it's not so easy. The UK generation balance sits around 300g CO2eq/kWh, more or less, https://www.carbonindependent.org/15.html
That means your typical EV giving 4mls/kWh range will be responsible for around 75g/mile or about 50g/km (to use round figures). That compares to somewhere round 120g/km real world for a similar petrol ICE vehicle. A lot less but by no means "zero".
There are however countries in the world where the generation is heavily carbon based and the generation figures are much nearer 600 or 700g CO2eq/kWh, and the real CO2 emissions are almost equal for ICE and EV. Places like Scandinavia of France (nuclear) mean much lower CO2eq values.

As far as I can see, one major issue with recharging EV very quickly isn't just the limitations of the batteries but of the charging power required. To put 40kWh into a car in 10mins means 240kW power delivery. Refuelling a car with petrol at a typical 30 lt/min is delivering chemical energy at around 15MW (22kg x 43MJ per min). Even allowing for an ICE efficiency in the 25-30% bracket, that's still 4 or 5MW of effective motive power delivery. Today's rapid chargers are around 50kW, so pouring petrol into a car is giving 100x the "range/minute" refuelling rate of even a fast charger.

I don't think EV recharging will get very close to petrol/diesel refuelling speeds simply because of the energy density of HC fuels, but that's not important. If it can get down to a "reasonable" time in a practically deliverable way then fine.

We are in interesting times.

[Expatman]

Sure are in interesting times! Basically what you are saying is that technically it will be almost impossible to fuel a car with electricity in the same time as petrol. That is the real world problem, imagine the queues at recharging stations on a busy holiday weekend on routes to the West Country even if recharging time was only 30 minutes.  Chaos with lines of stationary waiting cars on the motorway. The queues are bad enough now with cars waiting to fill with petrol!
There has to be a better solution.

[John Ratsey]

Sure are in interesting times! Basically what you are saying is that technically it will be almost impossible to fuel a car with electricity in the same time as petrol.

Didn't one of the manufacturers toy with replaceable batteries? That's where a battery-swapping robot would be ueful.

Alternatively, people will have to wind the clock back 50 years or so and take fewer holiday trips with no heading off to the second home each weekend.

Anyway, we're wandering off-topic. There's a long discussion about EVs elsewhere in this forum.

[Foksadure]

Didn't one of the manufacturers toy with replaceable batteries? That's where a battery-swapping robot would be ueful.

Tesla did a demo of such a process quite a while back.

And I think one stop shop quick battery swap is available for Nio (chinese EV carmaker) owners.

https://www.caranddriver.com/news/a33670482/nio-swappable-batteries-lease/

[JazzMusic]

Keep in mind that the Jazz is always moved by its electrical engine, albeit powered by the petrol engine

...except at high speed when direct engine drive takes over.

The clutch is activated >50 mph which actually isn't a very high speed.

The highway mpg is terrible in the Jazz, > 6 l/100 above 80 mph.

Plus the ZE2 Insight gets a better mileage during winter and highspeed. And it feels a lot more sporty to drive. I hate that the battery level is kept so low because I'd like the extra punch here and there.

[Downsizer]

The clutch is activated >50 mph which actually isn't a very high speed.

The highway mpg is terrible in the Jazz, > 6 l/100 above 80 mph.

50 mph was a high speed when I were a lad!  80 mph is illegal in UK, and if we’re serious about tackling climate change we should be imposing a limit of 60 mph.  It would save motorists a lot of money without much loss of time.

[John Ratsey]

50 mph was a high speed when I were a lad!  80 mph is illegal in UK, and if we’re serious about tackling climate change we should be imposing a limit of 60 mph.  It would save motorists a lot of money without much loss of time.

Bring back this for a start http://news.bbc.co.uk/onthisday/hi/dates/stories/december/15/newsid_2559000/2559807.stm .

The Insight is a much more aerodynamic vehicle and hence better for high speed cruising. The Jazz is designed to give good internal capacity for a relatively small road footprint and is consequently less aerodynamic.

[Downsizer]

Bring back this for a start http://news.bbc.co.uk/onthisday/hi/dates/stories/december/15/newsid_2559000/2559807.stm .

I’m drifting off topic, but when these speed limits were in force, the government was also considering petrol rationing.  As the personnel manager of a machine tool maker, I held the coupons allocated to the company, but fortunately I never had to decide who should get them!

[Jocko]

I remember my dad getting sent a book of petrol coupons but I thought it was early than 1974 (no, we're not talking about the war).
It must have been 1973-4. Previous to that was 1956 and we didn't have a car then.

[Expatman]

Don’t forget that although 50 MPH might have been considered a good speed that in the 50’s and 60’s cars rarely achieved much more than 35 MPG and the roads were dismal by todays standards. Modern cars are quite capable of 45-50 MPG at a steady 70 MPH on motorways and many of the new hybrids are capable of up to 60 MPG at motorway speeds. Reliability, tyres, roadholding, comfort and safety features are infinitely better than previous generation cars.
Old ‘uns like us tend to view motoring in our youth through rose tinted glasses and remember the good (open roads) while forgetting the bad - like it taking all day to get anywhere because all the roads went through towns rather than round them - the jams at Exeter in the summer are legendary!