Solar in winter months?

[wildebus]

View attachment 56052



You might not be touching the accelerator, but the engine control IS!

I think really a graph showing consumption/Hr rather than a consumption/mile is needed, especially if wanting to judge against a stationary engine, such as a generator.
That graph above could imply at first glance that an engine is using less fuel at higher speeds but that is not the case of course. (it does show that you get better efficiency driving at higher speeds (upto a point) though, which is interesting and might surprise Mr and Mrs Trilby)

 

[in h]

You might not be touching the accelerator, but the engine control IS!

The engine is idling. If I shift from N to D, it does not slow down noticeably, but the tiny pressure on the transmission makes the car very slowly build up speed.
Yes, there is some work being done by the engine, but no more than if it was idling with the HOLD on on the brakes.
It is still idling unless I press the accelerator pedal.
If you choose not to consider that to be idling, that's up to you. I have a different opinion.

 

[in h]

I think really a graph showing consumption/Hr rather than a consumption/mile is needed, especially if wanting to judge against a stationary engine, such as a generator.

You could extrapolate that by using the MPG and MPH to calculate GPH, but not down to 0 MPH

 

[in h]

Ignoring the Prius (which is really a red herring) that graph seems to show that there is a fixed amount of fuel being used at stationary, then a straight line graph up to about 40mph, after which presumably wind resistance starts to be significant.
By regressing the straight line back, you should be able to calculate the stationary consumption quite easily.

 

[St3v3]

It is still idling unless I press the accelerator pedal.

No. The amount of fuel going into the engine changes to match the load. Idle is only ever NO load. Not a little bit of load, NO load.

Engine RPM can remain at idle speed, but it's under load. Therefore, not idle.

Yes, there is some work being done by the engine, but no more than if it was idling with the HOLD on on the brakes.

And this is the point you are missing. You're swapping the extra power the engine is making from when it was in N from fighting the brakes (via the torque converter) to moving the car.

And it is making extra power, you just didn't notice because the RPM didn't change, the control system took care of that by adding more fuel.

 

[in h]

They all seem to show about 10mpg at 10mph, 20mpg at 20mph and (more roughly) 30mpg at 30mph
Which suggests that it is about 1 gph until wind resistance comes into play.
I assume that these are constant speed, steady state figures.
Bear in mind that these are petrol engines. Diesels idle much more efficiently.

 

[in h]

No. The amount of fuel going into the engine changes to match the load. Idle is only ever NO load. Not a little bit of load, NO load.

Ah, I see that you missed the difference between "no load" and "idle"
If I leave it in Park with the engine running, that is no more and no less load than in Drive.
Do you consider neither to be "idle"?

 

[St3v3]

Ignoring the Prius (which is really a red herring

Correct, it's running on electric at the lower end.

that graph seems to show that there is a fixed amount of fuel being used at stationary, then a straight line graph up to about 40mph, after which presumably wind resistance starts to be significant.
By regressing the straight line back, you should be able to calculate the stationary consumption quite easily.

No, because you can't divide by zero.

 

[in h]

No, because you can't divide by zero.

Maths clearly isn't your strong point.

 

[St3v3]

If I leave it in Park with the engine running, that is no more and no less load than in Drive.

It is less load, the gearbox isn't engaged, and fighting against the brakes. The extra energy is being turned to heat in the torque converter when in drive.

EDIT: to actually answer your question, P and N are idle, D is not.

Maths clearly isn't your strong point.

Ok, enlighten me. What's 100 divided by 0?

Speed becomes zero at the bottom of the chart. If you solve MPH and MPG for GPH, you'll have to divide by zero

 

[wildebus]

You could extrapolate that by using the MPG and MPH to calculate GPH, but not down to 0 MPH

I know you could to a point, but:
a) if you glance at that graph rather then analyzing it - or you try to look at the graph on your small screen instead of your 36" monitor - you can get the wrong impression;
b) at the lower speeds there is no data to inform.

 

[St3v3]

On another note, that dip in the civic graph is interesting. Are they all VVT? I wonder if it's something to do with that? Designed to make the most MPG at the tested 55mph, but be capable of flowing the air to make the high power figures they do per ltr maybe?

 

[in h]

I wondered about that, and why they are all so poor. I guess that it's probably because they are all petrol-engined and not specially long vehicles. The dip in the civic is probably to do with airflow past the body, causing extra turbulence at certain speeds. Well, that's my guess, anyway.

 

[in h]

EDIT: to actually answer your question, P and N are idle, D is not.

OK, a difference of opinion there.

Ok, enlighten me. What's 100 divided by 0?

In this instance, it is "irrelevant"
Think a bit more about how to work out a regression.

 

[in h]

a) if you glance at that graph rather then analyzing it - or you try to look at the graph on your small screen instead of your 36" monitor - you can.

I'm looking at it on a mere 24" monitor. The big one is 39" but it's a 4K display, so unless I scale it up, things are smaller on that than on this one!
It's pretty easy to see that the curves have a linear range, and you can see where that straight line would meet the Y axis if it regressed back down. From that it's not hard to work out the offset from zero.

 

[St3v3]

. The dip in the civic is probably to do with airflow past the body, causing extra turbulence at certain speeds. Well, that's my guess, anyway.

Possible, I don't know what model the graph refers. I think I remember they did a huge amount of work to make the newer type R produce positive downforce. It sticks in my head because my toy was the first/one of maybe? production car to do so back in the early '90s.

 

[St3v3]

OK, a difference of opinion there.

For me it's both the dictionary definition of idle meaning NO work, and the experience I have with car mechanics and their control systems, both electrical and mechanical. Idle there means under no load.

Coupled with the fact that engaging drive loads the engine, it's pretty clear. You can even hear the engine tone change, even though it's at the same rpm. Leave it like that too long and the TC will overheat.

Also the curves are not linear where you are suggesting extrapolating them. To make the curve straight on something that is clearly not in other areas is dubious at best, but where we do have data is just plain wrong.



See the black line? We're getting 5mpg at 0mph. Clearly wrong.

But, hey ho, I think we're in danger of going idly around in circles!

 

[Molly 3]

The battery is just an electricity bucket. You can probably charge it to 95% full, discharge to 50% full, so the effective capacity is 45% of 105Ah, which is around 47Ah.
In turn, that's about 564 watt hours, the equivalent of 40 grammes of LPG (costing about 5p). Sadly, gas won't run your TV!

My TV runs happily on gas using my gas powered Honda

 

[1 cup]

The Toyota is eletric upto 38mph I thought?

 

[Deleted member 132]

Om my Hymer S700 I had 240w of Solar and 3 x 110Ah Batteries. In Spain from just before Christmas to mid February I had to look as a way of topping up. We had lights and TV everything else was on gas.. I had B2B and a Gasparini 12v 20 amp generator, but found it easier to find a camper stop with EHU for a night one night per week This offered the chance to top up drinking water, get rid of waste and visit the shops. With the B2B we could charge where we were if needed, the same went for the generator, However we chose our stops for the solitude and quiet so we were not inclined to spoil this with the engines running. We were fine on solar and moving about for the rest of the year where ever we were.