How is EV time calculated?

[nielshm]

I've been wondering how EV time is calculated. It's not just the engine off and EV drive. And it's not just then electricity is flowing from Battery to the electric motor. 

Yesterday I made a very short drive to fill up with gas. Engine was cold. 0,5 mile drive and 0% EV time. Of course all is about heating up. On the drive back home, also 0,5 mile, a bit of Battery power starts to flow, but the engine never shuts off. EV time is calculated to 10%. 

[Timmon]

Did the engine drop to 1K revs, as it does, can't remember why? Partly to do with heating the water in winter, and also something to do with ensuring the brakes have power etc.

 I think if that happens and the engine is not actually driving the wheels, that is counted as EV time. Not sure if when the Battery is assisting the ICE, that also counts as EV time. I know the EV time always seems higher that you think, because you tend to think of full engine shut off as EV, and for me anyway, with little town driving, the ICE runs much of the time during my trips.

[bigblock]

This is an interesting subject which brings me on to mpg calculations. Lets say a hybrid does 60 mpg average on a full tank. Well actually it's doing a lot less than that in reality because some of the time the vehicle is using electric power meaning it's not burning fuel during the 60 mpg calculation. So on a full tank the 60 mpg average is wrong. Can anybody through a bit more light on my thinking if I am wrong.

[frizzbee30]

My vehicle certainly counts ev time in mpg, and PHEV figures quote the WLTP circuit figures in their mpg.

So, to all intense purposes,  it is accurate.

No, the egines alone don't get those figures,  or emissions, and can actually be much worse, especially PHEV, but ultimately it's running cost, which is miles on the fuel used.

[Jiff]

Bigblock

I tend to take thing to ludicrous extremes to work out what is true. From your thinking, if a car travelled 999 miles on electric power, plus 1 mile on the engine & used 1 gallon of fuel, you would say the car did 1 mile / gallon, I'd say it did 1000 miles per gallon. MPG isn't  about the engine, it's all about the vehicle. 

[bigblock]

5 minutes ago, frizzbee30 said:

My vehicle certainly counts ev time in mpg, and PHEV figures quote the WLTP circuit figures in their mpg.

So, to all intense purposes,  it is accurate.

No, the egines alone don't get those figures,  or emissions, and can actually be much worse, especially PHEV, but ultimately it's running cost, which is miles on the fuel used.

That's what I was trying to explain Ian.. The engine alone does not get those mpg figures it's a combined electric / fuel figure as opposed to a normal engined vehicle where mpg is much more straight forward to calculate. I get what you are saying though.

 

[bigblock]

3 minutes ago, Jiff said:

Bigblock

I tend to take thing to ludicrous extremes to work out what is true. From your thinking, if a car travelled 999 miles on electric power, plus 1 mile on the engine & used 1 gallon of fuel, you would say the car did 1 mile / gallon, I'd say it did 1000 miles per gallon. MPG isn't  about the engine, it's all about the vehicle. 

Thats very interesting stuff Jiff. I like it.

[frizzbee30]

Actually,  when I was looking for my next company car, some PHEV's were quoting 100, 150+ mpg, I think that was before the second WLTP, only issue was once discharged,  I saw reports of mpg around 20 to 30 ish for the same vehicle. 

So much PR, that's why I'm made up with the average 55, and up to 64 my 2.0 excel has done (pre winter), especially as I claim a fixed rate per mile for business journeys!!

[AndrueC]

3 hours ago, bigblock said:

This is an interesting subject which brings me on to mpg calculations. Lets say a hybrid does 60 mpg average on a full tank. Well actually it's doing a lot less than that in reality because some of the time the vehicle is using electric power meaning it's not burning fuel during the 60 mpg calculation. So on a full tank the 60 mpg average is wrong. Can anybody through a bit more light on my thinking if I am wrong.

You're overthinking it, or confusing 'the mpg from an engine' (which is meaningless) with 'the mpg from a vehicle' (which is very meaningful but says nothing about the source(s) of motive power used during the journey). If a car consumes 1 gallon driving 10 miles it's 10mpg. If it consumes 1 gallon driving 100 miles then it's 100 mpg. Mpg is simply 'the amount of petrol burnt in order to complete the journey'. Whether there is a Battery or an overcited budgerigar helping the engine out part of the time isn't relevant.

There is no practical difference as to what the engine was doing during that journey or for how much of it. It exists to answer the question 'If I want to drive 100 miles how much fuel do I need to buy? Whether the fuel is burnt at the beginning, end or throughout the journey simply doesn't matter.

Put yet another way: a vehicle with a 1,000,000,000hp engine that fires once when you first press the accelerator then relies on you coasting from several hundred mph to your destination can have exactly the same mpg as a vehicle with 10hp engine that runs continuously.

[bigblock]

30 minutes ago, AndrueC said:

You're overthinking it, or confusing 'the mpg from an engine' (which is meaningless) with 'the mpg from a vehicle' (which is very meaningful but says nothing about the source(s) of motive power used during the journey). If a car consumes 1 gallon driving 10 miles it's 10mpg. If it consumes 1 gallon driving 100 miles then it's 100 mpg. Mpg is simply 'the amount of petrol burnt in order to complete the journey'. Whether there is a battery or an overcited budgerigar helping the engine out part of the time isn't relevant.

There is no practical difference as to what the engine was doing during that journey or for how much of it. It exists to answer the question 'If I want to drive 100 miles how much fuel do I need to buy? Whether the fuel is burnt at the beginning, end or throughout the journey simply doesn't matter.

Put yet another way: a vehicle with a 1,000,000,000hp engine that fires once when you first press the accelerator then relies on you coasting from several hundred mph to your destination can have exactly the same mpg as a vehicle with 10hp engine that runs continuously.

That's what got me.The mpg from the engine rather than the vehicle. Great explaination Andrue. 

[TonyHSD]

Best to see how your engine is doing is to switch the dash to current consumption and watch your MPG while accelerating, cruising and while in ev mode , my one shows 99mpg which means no fuel been burned while on electric and with moderate acceleration numbers are around 26-36mpg, cruising between 40-64mpg, this can give you idea for the numbers you are interested. At the end this hybrid power train works most of the time in combination of both power sources, with some exceptions. 
Regards 

[Timmon]

I think you have to just think in terms of total vehicle mpg for a hybrid. If you start trying to break it back to actual mpg from the ice only, that becomes unfair on the ICE, because it has to lug a heavy Hybrid Battery around, a load a non Hybrid Corolla would not have. You could look to the USA for a comparison, where 1.8 and 2 ltr engines / powertrains are available as non Hybrid, , but then there is the USA gallon against the UK gallon etc. And how do you calculate the allowance for the Hybrid Battery, etc. Sounds too much hassle to be honest, but there are probably some mathematicians out there who would love to have a go!  The same issue in reverse, how far to a charge does the EV part of the Hybrid system take you, bearing in mind it has to lug an ICE around with it.

[Bernard Foy]

I can just imagine 5000 excited  budgerigars harnessed up to a Toyota Hybrid 🤣😂. Great analogy Andrue.👏👏

[AndrueC]

42 minutes ago, Bernard Foy said:

I can just imagine 5000 excited  budgerigars harnessed up to a Toyota Hybrid 🤣😂. Great analogy Andrue.👏👏

Heheh. I shared my house with a budgie for nearly ten years and when driving us back from my parent's house in North Wales when we got to Rhuallt hill I used to tell him to flap and help out. The lazy sod never did 🙂

I also used to tell him to look out of the window when we were crossing the River Dee and River Ceriog but I think he looked once and was scared to ever again 🙂

One of my favourite memories of him was him hanging from the roof of his cage while we were travelling at 70mph along a motorway, tweeting away to the music. They might have small brains but budgies know how to enjoy themselves. Just don't ever expect them to help get your car up a steep hill 😄

[Bernard Foy]

On 12/7/2020 at 8:07 PM, AndrueC said:

Heheh. I shared my house with a budgie for nearly ten years and when driving us back from my parent's house in North Wales when we got to Rhuallt hill I used to tell him to flap and help out. The lazy sod never did 🙂

I also used to tell him to look out of the window when we were crossing the River Dee and River Ceriog but I think he looked once and was scared to ever again 🙂

One of my favourite memories of him was him hanging from the roof of his cage while we were travelling at 70mph along a motorway, tweeting away to the music. They might have small brains but budgies know how to enjoy themselves. Just don't ever expect them to help get your car up a steep hill 😄

 Well you were lucky my old bird keeps telling me how to drive the car 🤣😂🚗