No new diesel cars after 2030

[Raywood]

I would say the figures ae more noticeable on a 1,600 engine as against a 2,000 one simply because the power needed is higher in proportion to the engine size, so the percentage power drop for the larger engine is less and results in a lower percentage of fuel use.

 

[Jcloughie]

Its not the size of the engine, but the power it can produce.

I have seen varying reports of how much power AC needs, Some as low as 3kW and some as high as 10kW (12.5Hp). Let me be clear I'm only referring to the power input not its COP.

This amount of power will only be drawn when the A/C compressor is running, which as I pointed out above is not usually all the time

For example:- if you had a car with a 75kW engine (approx. 100bhp) with an AC of 7.5kW draw, you would only experience the drop in performance and reduction in fuel economy whilst the AC compressor is working. If the AC only operated for 50% of the time the average loss for performance will only be 3.75kW - If that caused a reduction in fuel economy of 10% for the whole journey there is some other variable not being taken into account.

Applying that logic to my car, gives a penalty of between 1.4% and 3.3%. I can live with that.

John

 

[Raywood]

I agree, I have never seen any difference in fuel consumption with it on or off.

 

[otherclive]

I agree, I have never seen any difference in fuel consumption with it on or off.

One way to check is at steady cruise on flat road just flip the cars econometer to instantaneous and turn the AC on. I’ve never done it as it’s nit something that bothers me.

 

[ProfJohnL]

I strongly suspect the biggest indicator that a driver would be aware of is the
apparent change in engine power when the AC cuts in, and how bigger change that is will vary depending on the vehicle.

Attempting to give a measurable difference outside of a lab will be difficult. In real life I'd be surprised if you could could detect a change in instantaneous MPG measurements, there are simply too many other real world variables.

I'm not about suggest you should attempt this on public roads, but if it were possible to run at max speed on a flat wind free surface then switching AC on, you would see the top speed drop.

It should be enough to know that as AC systems need power to operate that a car that power has to come from the fuel used in the car, and that means the fuel used to power the AC will detract form the vehicles range.

Due to the inherent inefficiencies of In ICE vehicles and the large fuel capacity the fuel used to power the AC the losses are less noticeable, but in an EV where the high efficency of the motor means any reduction in the battery charge available to drive the car will be more noticable.

 

[otherclive]

I strongly suspect the biggest indicator that a driver would be aware of is the
apparent change in engine power when the AC cuts in, and how bigger change that is will vary depending on the vehicle.

Attempting to give a measurable difference outside of a lab will be difficult. In real life I'd be surprised if you could could detect a change in instantaneous MPG measurements, there are simply too many other real world variables.

I'm not about suggest you should attempt this on public roads, but if it were possible to run at max speed on a flat wind free surface then switching AC on, you would see the top speed drop.

It should be enough to know that as AC systems need power to operate that a car that power has to come from the fuel used in the car, and that means the fuel used to power the AC will detract form the vehicles range.

Due to the inherent inefficiencies of In ICE vehicles and the large fuel capacity the fuel used to power the AC the losses are less noticeable, but in an EV where the high efficency of the motor means any reduction in the battery charge available to drive the car will be more noticable.

Darned if I’m winding it up to 137 mph and then switching anything on or off😂

 

[ProfJohnL]

Darned if I’m winding it up to 137 mph and then switching anything on or off😂

Spoil sport

 

[RogerL]

I strongly suspect the biggest indicator that a driver would be aware of is the
apparent change in engine power when the AC cuts in, and how bigger change that is will vary depending on the vehicle.

Attempting to give a measurable difference outside of a lab will be difficult. In real life I'd be surprised if you could could detect a change in instantaneous MPG measurements, there are simply too many other real world variables.

I'm not about suggest you should attempt this on public roads, but if it were possible to run at max speed on a flat wind free surface then switching AC on, you would see the top speed drop.

It should be enough to know that as AC systems need power to operate that a car that power has to come from the fuel used in the car, and that means the fuel used to power the AC will detract form the vehicles range.

Due to the inherent inefficiencies of In ICE vehicles and the large fuel capacity the fuel used to power the AC the losses are less noticeable, but in an EV where the high efficency of the motor means any reduction in the battery charge available to drive the car will be more noticable.

Max speed runs won't show the difference - most cars have a "wide open throttle" switch which will disengage the aircon compressor electrically, and on modern cars the alternator too

 

[Dustydog]

Silly question. So I’m towing charging my caravan battery and keeping the fridge cool on 12v. Does my EV have an alternator thing or does all the power to the caravan come from the EV battery?

 

[otherclive]

Silly question. So I’m towing charging my caravan battery and keeping the fridge cool on 12v. Does my EV have an alternator thing or does all the power to the caravan come from the EV battery?

From the battery of the car as running an alternator to supply the caravan would be inefficient as the alternator would have to be powered by the cars battery and there would be inherent losses. But the EV can regenerate from braking, going downhill, or easing off up to lights etc.


https://300mpg.org/projects/electro-metro/why-dont-electric-cars-have-alternators/

 

[ProfJohnL]

Silly question. So I’m towing charging my caravan battery and keeping the fridge cool on 12v. Does my EV have an alternator thing or does all the power to the caravan come from the EV battery?

Fundamentally all the power used in the car or caravan is derived from the EV battery.
However most EV batteries run at significantly more than 12V,s so there is probably a buck converter to keep the 12V systems running. A well designed buck converter will be at worst 80% efficient and depending on the amount of current it supplies can go as high as 95%.

Many EV's also have a 12V battery which will be charged from the main EV battery.

 

[JezzerB]

As stated most Evs have a 12v battery from whence you can is powered.

 

[Buckman]

If there is a connection to the rotation of the caravan wheels to generate the 12v would it be possible for that 12v to keep the fridge cool? This would eliminate the need for the vehicle to be cooling the fridge and also eliminate a battery bank in the caravan. Something along those lines anyway.

 

[otherclive]

If there is a connection to the rotation of the caravan wheels to generate the 12v would it be possible for that 12v to keep the fridge cool? This would eliminate the need for the vehicle to be cooling the fridge and also eliminate a battery bank in the caravan. Something along those lines anyway.

But the energy to rotate the caravan wheels comes from the car towing the caravan, and that cars battery and you have added the inefficiency of another rotating power source such as a “dynamo”. No such thing as eternal motion. A solar panel on the roof might be better as long as the extra weight doesn’t outweigh the solar energy gained.

 

[Raywood]

I have always wondered about a solar panel on the roof helping out. They are fairly light but not clear if they would be effective.

 

[ProfJohnL]

If there is a connection to the rotation of the caravan wheels to generate the 12v would it be possible for that 12v to keep the fridge cool? This would eliminate the need for the vehicle to be cooling the fridge and also eliminate a battery bank in the caravan. Something along those lines anyway.

Apart from the point that Otherclive makes about where the power ultimately comes from, your idea is not without merit. Considering we have had a number of posts that have told their fridge is not cooling when being towed, and it could be down to the car having a smart alternator that simple does not charge all the time. Connecting the fridge ( and caravan battery) by some means to use wheels motion to produce a power means it removes the need for cars to have separate charging circuits at the towing plugs as its all self contained in the caravan.

 

[Hutch]

Maybe a small RAT, Ram Air Turbine as used on some aircraft. To power a generator, only good when moving forward of course.
Just another Idea.

 

[otherclive]

Maybe a small RAT, Ram Air Turbine as used on some aircraft. To power a generator, only good when moving forward of course.
Just another Idea.

But even that takes power from the towing vehicle and the nett output would not be positive given its overall efficiency. So the cars battery would not benefit at all. At least a full roof low weight (flexible type) solar panel could be compensated for by taking few less bottles of wine, would not affect aerodynamics, and works whether the outfit is moving or not. And few tow at night.

 

[ProfJohnL]

Maybe a small RAT, Ram Air Turbine as used on some aircraft. To power a generator, only good when moving forward of course.
Just another Idea.

I think there may be some legal issues about the speed needed to get an air turbine working enough to generate 150W

 

[Hutch]

I think there may be some legal issues about the speed needed to get an air turbine working enough to generate 150W

I was a bit jokey about the RAT, but looking at the specs of this one for a boat, maybe the idea is not that far from the truth.

Rutland 914i Windcharger - Marlec

Rutland 914i is Marlec's most recent Windcharger boasting more output than its predecessor the Rutland 913. Battery charging windchargers.

www.marlec.co.uk

 

[Hutch]

Maybe a contained unit away from rotating parts could be possible, ducted away into a space. Terrible in traffic queues of course.

 

[otherclive]

Maybe a contained unit away from rotating parts could be possible, ducted away into a space. Terrible in traffic queues of course.

A Dyson in reverse perhaps?

 

[Guzzilazz]

I was a bit jokey about the RAT, but looking at the specs of this one for a boat, maybe the idea is not that far from the truth.

Rutland 914i Windcharger - Marlec

Rutland 914i is Marlec's most recent Windcharger boasting more output than its predecessor the Rutland 913. Battery charging windchargers.

www.marlec.co.uk

These cut out at over 35mph windspeed... Investigated one for the boat, glad I went to solar...

 

[Jcloughie]

I am informed that another problem with turbines for use on caravans, is the noise and vibration.

A neighbour attached an, admittedly larger, turbine to the side of his house. The building shook. It came down. It might go unnoticed on a boat, but caravans don’t float!

John

 

[Hutch]

View: https://youtu.be/v223HkqHJbo


Yes they do