The all things EV chat thread

[Tashyboy]

Falling outta love with the CX5 and Ave seen the Lexus UX 250h hybrid. I think the hybrid tern is very loosely described, however the mileage is very good. How I never came across that car when looking a year ago is beyond me. Maybe the Lexus badge made me think it was outta my price range.

 

[Bunkermagnet]

Possibly, but I've not heard of losing lots of range in an ICE when loaded up. Can Bunkermagnet confirm what happens with his diesel van?

A full tank of fuel only weighs about as much as one person, so that seems a minor factor compared to loading a van up with lots of stuff.

The thing that affects my van mileage is how hard I press the loud pedal.
How much load 8 have doesn't seem to make any difference.

 

[Bunkermagnet]

Do you think there is a stigma on t6 plus tradies having higher end tools?

I had a Kia ceed as a pool car back in 2012 and other than cheap seats for long mileage, the car was bullet proof.

I dont think there's any stigma to owning a VW T6. I would say the VW"s have progressively become less reliable as they've developed.
The biggest thing about the Transporters up until the latest Transit collaboration is their security. Aside from the glass, you wont see a Transporter with holes punched through the doors to disable the locks and alarm.

 

[RichA]

Can anyone explain the physics of why adding load impacts range so much more on an EV than an ICE? I just can't fathom why.

I didn't know this; I did a little AI research because I was interested...

Average electric van battery is about 80kwh.
Average diesel van has a 70 litre diesel tank. 70 litres of diesel produces the equivalent of about 700kwh, most of which isn't converted into mileage.

Electric is very efficient.
Diesel is massively less efficient but there is a huge buffer of wasted energy that can be used to shift a greater load without impacting so severely on consumption. Electric just doesn't have that buffer.

 

[jim8flog]

Possibly, but I've not heard of losing lots of range in an ICE when loaded up. Can Bunkermagnet confirm what happens with his diesel van?

A full tank of fuel only weighs about as much as one person, so that seems a minor factor compared to loading a van up with lots of stuff.

But that is the same as having four bags of say cement in a van.

Not range but performance- I have had cars that I noticed the difference with a passenger in the car.

I used to drive a 2.5 litre diesel Transit and used to notice the difference when it was loaded up when we went on holiday compared to me driving around on my own but too long ago to tell you what that difference was exactly.

 

[RichA]

But that is the same as having four bags of say cement in a van.

Not range but performance- I have had cars that I noticed the difference with a passenger in the car.

I used to drive a 2.5 litre diesel Transit and used to notice the difference when it was loaded up when we went on holiday compared to me driving around on my own but too long ago to tell you what that difference was exactly.

Anecdotal...

Most of the mileage in my BMW 520d is just me on my own without luggage. It averages 50.7 mpg.

In the summer I went away with a couple of pals so it was carrying an additional 2 adult males, 3 sets of clubs, 3 trolleys and luggage for 3 days away. It averaged 50.4 mpg.

 

[cliveb]

Electric is very efficient.
Diesel is massively less efficient but there is a huge buffer of wasted energy that can be used to shift a greater load without impacting so severely on consumption. Electric just doesn't have that buffer.

No argument that electric is way more efficient than ICE.

But the highlighted bit implies that a diesel engine gets more efficient when it's hauling a bigger load. That makes no sense; I'm not buying it.

 

[RichA]

No argument that electric is way more efficient than ICE.

But the highlighted bit implies that a diesel engine gets more efficient when it's hauling a bigger load. That makes no sense; I'm not buying it.

It doesn't. It's just largely drawing on some of the 90% of energy that is otherwise being wasted.
Whereas an electric motor has only a tiny amount of wasted energy so the extra energy needed for dragging the extra load is all coming out of the battery on top of the usual.

 

[Lord Tyrion]

Falling outta love with the CX5 and Ave seen the Lexus UX 250h hybrid. I think the hybrid tern is very loosely described, however the mileage is very good. How I never came across that car when looking a year ago is beyond me. Maybe the Lexus badge made me think it was outta my price range.

Please do get one and then review it. I'm not looking to change my car yet but when I do this is one of interest. You can give a golfers review

 

[cliveb]

It doesn't. It's just largely drawing on some of the 90% of energy that is otherwise being wasted.

If that is true, then it's precisely the definition of getting more efficient as the load goes up.

But I don't believe it's true. If a diesel engine is wasting lots more energy when it's not hauling a big load, where does that wasted energy go?

 

[larmen]

If that is true, then it's precisely the definition of getting more efficient as the load goes up.

But I don't believe it's true. If a diesel engine is wasting lots more energy when it's not hauling a big load, where does that wasted energy go?

Heat and noise.

The one where EVs lose range when they have to heat in winter, ICE cars heat all year around

 

[RichA]

If that is true, then it's precisely the definition of getting more efficient as the load goes up.

But I don't believe it's true. If a diesel engine is wasting lots more energy when it's not hauling a big load, where does that wasted energy go?

Fair enough. Based on the info I found online it maybe goes from wasting 90% of its potential energy to wasting 85% of it (guessing). I guess it's semantics as to when you consider something being better or less dreadful.

The other bit: large amounts of heat in the exhaust gas and engine and a bit of noise.

The battery provides the electric motor with pretty much exactly the amount of energy it is asked for. If the motor is required to do more work then it uses more energy accordingly.
The diesel engine is producing 5 to 10 times more energy than is being converted into movement so there is already a buffer zone of energy being wasted that it is tapping into to some extent.

 

[cliveb]

Heat and noise.

The one where EVs lose range when they have to heat in winter, ICE cars heat all year around

So you're saying a diesel engine creates a lot less heat when it's working hard, right? In other words, it's way more efficient when under load. That seems extremely unlikely to me. We all know that if you drive an ICE car hard, mpg seriously goes down. If you use more fuel to cover the same number of miles, that's an indication that it's LESS efficient.

NB. We can ignore noise: sound has very little energy. (And in any case, an ICE generates more noise when it's working hard).

 

[RichA]

So you're saying a diesel engine creates a lot less heat when it's working hard, right? In other words, it's way more efficient when under load. That seems extremely unlikely to me. We all know that if you drive an ICE car hard, mpg seriously goes down. If you use more fuel to cover the same number of miles, that's an indication that it's LESS efficient.

NB. We can ignore noise: sound has very little energy. (And in any case, an ICE generates more noise when it's working hard).

Of course it doesn't create less heat when it's working hard. Has anybody suggested that?

This AI explanation makes sense to me...

Question: How can the efficiency of a diesel engine in a van improve as the load being transported increases?

It might seem counterintuitive, but a diesel engine actually operates more thermodynamically efficiently when it is under a significant load (like carrying a full van) compared to when it is idling or carrying very little.
While a heavier van will always consume more total fuel to move, the engine itself becomes better at converting the energy in that fuel into actual movement rather than wasting it as heat or friction.
Here is how the efficiency improves as the load increases:
1. Reduction of "Pumping Losses"
Unlike gasoline engines, diesel engines do not have a throttle butterfly valve to restrict air. In a gas engine, when the load is low, the engine has to fight to "suck" air past a nearly closed throttle, which wastes energy (pumping losses).
* At High Load: The diesel engine's cylinders are filled with a full charge of air. The increased fuel injection matches this air more effectively, meaning the engine performs more useful work per stroke relative to the energy spent just moving air in and out.
2. Higher Mechanical Efficiency
Every engine has a certain amount of internal friction—the energy required just to keep the pistons moving, the oil pumping, and the gears turning.
* The "Fixed Cost": Think of friction as a "fixed tax." If your engine is barely working (low load), that friction "tax" might take up 40% of the energy produced.
* Scaling Up: When you increase the load, the total power output increases significantly, but the internal friction stays relatively constant. Therefore, the friction becomes a smaller percentage of the total energy produced, raising the overall mechanical efficiency.
3. Improved Thermal Efficiency
Diesel engines rely on compression ignition. For the fuel to burn completely and efficiently, the combustion chamber needs to be hot.
* Better Combustion: At higher loads, the combustion chamber temperatures rise. This heat helps the injected diesel fuel atomize and ignite more completely.
* Energy Conversion: As the load increases, the "Brake Thermal Efficiency" (the ratio of useful work to fuel energy) typically rises until it hits a "sweet spot" (usually around 70–80% of the engine's maximum load).
4. Turbocharger Optimization
Most modern van engines are turbocharged. Turbochargers are powered by exhaust gases.
* Low Load: At low loads, there isn't much exhaust pressure, so the turbo spins slowly and provides little "boost."
* High Load: As you load the engine, more exhaust is produced. This spins the turbo faster, forcing more dense air into the engine. This allows for a leaner, more efficient burn and better power delivery.
Summary Table: Low Load vs. High Load
| Feature | Low Load (Empty Van) | High Load (Full Van) |
|---|---|---|
| Fuel Burn | Less complete (cooler) | More complete (hotter) |
| Friction Loss | High % of total power | Low % of total power |
| Turbo Boost | Minimal | Optimized |
| Specific Efficiency | Lower (more fuel per unit of work) | Higher (less fuel per unit of work) |
> Note: While the engine is more efficient at high loads, you will still see a lower MPG (Miles Per Gallon) because the total amount of work required to move the extra weight is much higher.

 

[Oddsocks]

Anecdotal...

Most of the mileage in my BMW 520d is just me on my own without luggage. It averages 50.7 mpg.

In the summer I went away with a couple of pals so it was carrying an additional 2 adult males, 3 sets of clubs, 3 trolleys and luggage for 3 days away. It averaged 50.4 mpg.

It’s this that stopping me chopping the a4 in early. 55-60mpg as an average, that doesn’t matter if my heating or air con is on, lights etc etc.

 

[cliveb]

Of course it doesn't create less heat when it's working hard. Has anybody suggested that?

This AI explanation makes sense to me...

Question: How can the efficiency of a diesel engine in a van improve as the load being transported increases?

It might seem counterintuitive, but a diesel engine actually operates more thermodynamically efficiently when it is under a significant load (like carrying a full van) compared to when it is idling or carrying very little.
While a heavier van will always consume more total fuel to move, the engine itself becomes better at converting the energy in that fuel into actual movement rather than wasting it as heat or friction.
Here is how the efficiency improves as the load increases:
1. Reduction of "Pumping Losses"
Unlike gasoline engines, diesel engines do not have a throttle butterfly valve to restrict air. In a gas engine, when the load is low, the engine has to fight to "suck" air past a nearly closed throttle, which wastes energy (pumping losses).
* At High Load: The diesel engine's cylinders are filled with a full charge of air. The increased fuel injection matches this air more effectively, meaning the engine performs more useful work per stroke relative to the energy spent just moving air in and out.
2. Higher Mechanical Efficiency
Every engine has a certain amount of internal friction—the energy required just to keep the pistons moving, the oil pumping, and the gears turning.
* The "Fixed Cost": Think of friction as a "fixed tax." If your engine is barely working (low load), that friction "tax" might take up 40% of the energy produced.
* Scaling Up: When you increase the load, the total power output increases significantly, but the internal friction stays relatively constant. Therefore, the friction becomes a smaller percentage of the total energy produced, raising the overall mechanical efficiency.
3. Improved Thermal Efficiency
Diesel engines rely on compression ignition. For the fuel to burn completely and efficiently, the combustion chamber needs to be hot.
* Better Combustion: At higher loads, the combustion chamber temperatures rise. This heat helps the injected diesel fuel atomize and ignite more completely.
* Energy Conversion: As the load increases, the "Brake Thermal Efficiency" (the ratio of useful work to fuel energy) typically rises until it hits a "sweet spot" (usually around 70–80% of the engine's maximum load).
4. Turbocharger Optimization
Most modern van engines are turbocharged. Turbochargers are powered by exhaust gases.
* Low Load: At low loads, there isn't much exhaust pressure, so the turbo spins slowly and provides little "boost."
* High Load: As you load the engine, more exhaust is produced. This spins the turbo faster, forcing more dense air into the engine. This allows for a leaner, more efficient burn and better power delivery.
Summary Table: Low Load vs. High Load
| Feature | Low Load (Empty Van) | High Load (Full Van) |
|---|---|---|
| Fuel Burn | Less complete (cooler) | More complete (hotter) |
| Friction Loss | High % of total power | Low % of total power |
| Turbo Boost | Minimal | Optimized |
| Specific Efficiency | Lower (more fuel per unit of work) | Higher (less fuel per unit of work) |
> Note: While the engine is more efficient at high loads, you will still see a lower MPG (Miles Per Gallon) because the total amount of work required to move the extra weight is much higher.

All the above might make for a little bit of improved efficiency under load, but it would be minimal.

I've also been doing a bit more research and think I've found an explanation that makes much more sense:

More energy is required to haul heavier loads. Let's suppose 50% more energy is needed.

This means an EV will need to use about 50% more energy, because it's very efficient.

A diesel is far less efficient. It's wasting 80% of the fuel to heat. Of the fuel it uses, only 20% is converted to motive power. So to get 50% more motive power, it only needs to consume 50% more than the 20% of the fuel it had previously been using for motive power. In other words, 10% more fuel overall. This is the main reason for the enormous difference in range loss for EVs compared to diesels.

 

[RichA]

All the above might make for a little bit of improved efficiency under load, but it would be minimal.

I've also been doing a bit more research and think I've found an explanation that makes much more sense:

More energy is required to haul heavier loads. Let's suppose 50% more energy is needed.

This means an EV will need to use about 50% more energy, because it's very efficient.

A diesel is far less efficient. It's wasting 80% of the fuel to heat. Of the fuel it uses, only 20% is converted to motive power. So to get 50% more motive power, it only needs to consume 50% more than the 20% of the fuel it had previously been using for motive power. In other words, 10% more fuel overall. This is the main reason for the enormous difference in range loss for EVs compared to diesels.

Oh. So the diesel becomes more efficient under load then?

 

[Tashyboy]

Please do get one and then review it. I'm not looking to change my car yet but when I do this is one of interest. You can give a golfers review

Trust me, I am absolutely gutted that I never saw it when I was looking for a new car 15 months ago.Am sure the Lexus name put me off looking, but 50 mpg is better than the 36 am getting now. Just don’t have a clue how to mention it to Missis Tash.

 

[Bunkermagnet]

Falling outta love with the CX5 and Ave seen the Lexus UX 250h hybrid. I think the hybrid tern is very loosely described, however the mileage is very good. How I never came across that car when looking a year ago is beyond me. Maybe the Lexus badge made me think it was outta my price range.

Fpr why?
I love mine. Its a comfy ride, nice handling and driving position, boots a good size shat takes all the golf gear and more.....
As I say, I love mine

 

[cliveb]

Oh. So the diesel becomes more efficient under load then?

Now you're just fishing. But it's Christmas so I forgive you