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Post by mick on Aug 18, 2024 8:53:40 GMT
I'm obviously missing something here. Can someone tell me where my stupidity is?
Take a petrol engine. Put 100 units of power into it (from the fuel) and get, say, 90 at the wheels because of the losses.
Take a battery. Put 100 of power in and get 95 at the wheels because of the losses.
Now combine them, Put 100 into the petrol engine and use it to charge the battery so the battery gets 90. Use that 90 to drive the car and get 85.5 at the wheels (.9*.95)
So why bother using the petrol engine to charge the battery?
Yes I know that's crazily simplistic but I'm trying to illustrate the point that using the engine to charge the battery introduces two lots of losses instead of one. BTW I 'get' regenerative charging - that's just recovering energy that would otherwise go to waste.
Clearly I have to be completely off the mark but I must have a blind spot and can't see my muddle headed thinking.
Help!!
Mick
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Post by peterob on Aug 18, 2024 9:51:12 GMT
I'm obviously missing something here. Can someone tell me where my stupidity is?
Take a petrol engine. Put 100 units of power into it (from the fuel) and get, say, 90 at the wheels because of the losses.
Take a battery. Put 100 of power in and get 95 at the wheels because of the losses.
Now combine them, Put 100 into the petrol engine and use it to charge the battery so the battery gets 90. Use that 90 to drive the car and get 85.5 at the wheels (.9*.95)
So why bother using the petrol engine to charge the battery?
Yes I know that's crazily simplistic but I'm trying to illustrate the point that using the engine to charge the battery introduces two lots of losses instead of one. BTW I 'get' regenerative charging - that's just recovering energy that would otherwise go to waste.
Clearly I have to be completely off the mark but I must have a blind spot and can't see my muddle headed thinking.
Help!!
Mick
The generator engine can run at constant speed and peak efficiency. It doesn't have to provide for a variable load. Edit: on a full hybrid that is. No efficiency gains on a mixed hybrid which is just an emissions work around for urban use. |
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Post by dreampolice on Aug 18, 2024 10:30:02 GMT
And a lot of the hybrids will only run on battery power at low speeds and for not many miles. As soon as you reach around 30 or accelerate quickly the engine is used. So for every other than tootling around town the engine is used but add to that the extra weight of the battery etc that it is then carrying around.
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Post by mick on Aug 18, 2024 10:45:36 GMT
And a lot of the hybrids will only run on battery power at low speeds and for not many miles. As soon as you reach around 30 or accelerate quickly the engine is used. So for every other than tootling around town the engine is used but add to that the extra weight of the battery etc that it is then carrying around. I don't tire of watching the display on mine. It shows where the power is coming from and where it's going.
Sometimes the wheels are being driven by just battery (at all sorts of speeds - even on M'way). Sometimes just engine and sometimes battery and engine together (steep hills for example). Then the battery gets charged by the engine. Sometimes that's all the engine is doing and sometimes the engine is driving the wheels and charging at the same time. The battery also gets charged during coasting downhill or in fact at pretty well any time my foot is off the accelerator.
It's fascinating to watch and amazing how quickly it changes from mode to mode. I need to watch that I don't get distracted.
Mick
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Post by spinno on Aug 18, 2024 10:52:46 GMT
And a lot of the hybrids will only run on battery power at low speeds and for not many miles. As soon as you reach around 30 or accelerate quickly the engine is used. So for every other than tootling around town the engine is used but add to that the extra weight of the battery etc that it is then carrying around. I don't tire of watching the display on mine. It shows where the power is coming from and where it's going.
Sometimes the wheels are being driven by just battery (at all sorts of speeds - even on M'way). Sometimes just engine and sometimes battery and engine together (steep hills for example). Then the battery gets charged by the engine. Sometimes that's all the engine is doing and sometimes the engine is driving the wheels and charging at the same time. The battery also gets charged during coasting downhill or in fact at pretty well any time my foot is off the accelerator.
It's fascinating to watch and amazing how quickly it changes from mode to mode. I need to watch that I don't get distracted.
Mick
But you already are... |
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Post by dreampolice on Aug 18, 2024 10:55:23 GMT
And a lot of the hybrids will only run on battery power at low speeds and for not many miles. As soon as you reach around 30 or accelerate quickly the engine is used. So for every other than tootling around town the engine is used but add to that the extra weight of the battery etc that it is then carrying around. I don't tire of watching the display on mine. It shows where the power is coming from and where it's going.
Sometimes the wheels are being driven by just battery (at all sorts of speeds - even on M'way). Sometimes just engine and sometimes battery and engine together (steep hills for example). Then the battery gets charged by the engine. Sometimes that's all the engine is doing and sometimes the engine is driving the wheels and charging at the same time. The battery also gets charged during coasting downhill or in fact at pretty well any time my foot is off the accelerator.
It's fascinating to watch and amazing how quickly it changes from mode to mode. I need to watch that I don't get distracted.
Mick
We drove a self charging one on a test drive before my wife got her car last year. It seemed really pointless as it seemed to be mainly the engine driving it. We decided to go for an ICE again. Certainly until until fully electric are the best option for us. |
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Post by andy on Aug 18, 2024 11:10:42 GMT
I'm obviously missing something here. Can someone tell me where my stupidity is?
Take a petrol engine. Put 100 units of power into it (from the fuel) and get, say, 90 at the wheels because of the losses.
Take a battery. Put 100 of power in and get 95 at the wheels because of the losses.
Now combine them, Put 100 into the petrol engine and use it to charge the battery so the battery gets 90. Use that 90 to drive the car and get 85.5 at the wheels (.9*.95)
So why bother using the petrol engine to charge the battery?
Yes I know that's crazily simplistic but I'm trying to illustrate the point that using the engine to charge the battery introduces two lots of losses instead of one. BTW I 'get' regenerative charging - that's just recovering energy that would otherwise go to waste.
Clearly I have to be completely off the mark but I must have a blind spot and can't see my muddle headed thinking.
Help!!
Mick
The generator engine can run at constant speed and peak efficiency. It doesn't have to provide for a variable load. Edit: on a full hybrid that is. No efficiency gains on a mixed hybrid which is just an emissions work around for urban use.And makes doubly sure that the car will likely be junk after ~10 years so manufacturers can sell more new cars. |
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Post by nimbus on Aug 18, 2024 11:36:22 GMT
Hybrids generally have regenerative features, the economy is clearly better than an ICE engine alone and does away with the range problems of EVs. The problem as with EVs lies with the storage battery, it's bulk, weight and potential replacement cost along with increased danger of fire. I regard any vehicle with more than a normal battery type as a ticking time bomb, in the true sense and in the point of potential failure, the battery gives hybrids and EVs an immediate finite life.
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Post by zx9 on Aug 18, 2024 11:36:53 GMT
When Lexus brought out the RX400h they marketed it as a V6 with V8 performance which was refreshingly honest, the marketing of hybrids seems a lot more green washed these days.
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Post by mick on Aug 18, 2024 11:39:42 GMT
I don't tire of watching the display on mine. It shows where the power is coming from and where it's going.
Sometimes the wheels are being driven by just battery (at all sorts of speeds - even on M'way). Sometimes just engine and sometimes battery and engine together (steep hills for example). Then the battery gets charged by the engine. Sometimes that's all the engine is doing and sometimes the engine is driving the wheels and charging at the same time. The battery also gets charged during coasting downhill or in fact at pretty well any time my foot is off the accelerator.
It's fascinating to watch and amazing how quickly it changes from mode to mode. I need to watch that I don't get distracted.
Mick
But you already are... I may seem that way when I talk about it but in practice I turn off that display for almost all the time.
Mick
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Post by peterob on Aug 18, 2024 12:27:24 GMT
Hybrids generally have regenerative features, the economy is clearly better than an ICE engine alone and does away with the range problems of EVs. The problem as with EVs lies with the storage battery, it's bulk, weight and potential replacement cost along with increased danger of fire. I regard any vehicle with more than a normal battery type as a ticking time bomb, in the true sense and in the point of potential failure, the battery gives hybrids and EVs an immediate finite life. I should think it fairer to say that the economy of a plug-in-hybrid used primarily for short runs in an urban environment is better than that of a car with an ICE alone. I tend to agree that the promotion of EVs is a cynical way to reduce the passenger vehicle fleet because the low price end of the used car market will eventually disappear completely. I expect servicing costs will ramp up with age. My current "new" car at 10 yrs and 100k miles is seeing occasional electronic components fail at high replacement cost and I suspect 50% of the normal service cost is the licence to OEM that the garage pays for diagnostics software. It's a different fire risk to gasoline fuelled cars. I wouldn't say necessarily greater. |
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Post by davem399 on Aug 18, 2024 12:38:45 GMT
I’m not sure if my memory is correct, but were there “official” fuel consumption figures for some hybrids of well in excess of 100mpg?
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Post by peterob on Aug 18, 2024 14:01:01 GMT
I’m not sure if my memory is correct, but were there “official” fuel consumption figures for some hybrids of well in excess of 100mpg? Scaled up from journeys of less than 10 miles in electric mode probably. |
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Post by kate on Aug 18, 2024 15:03:06 GMT
How about the power and resources used to make them? Efficiency of the end product must be cancelled out by the power and mess caused by making them.
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Post by zou on Aug 18, 2024 15:09:05 GMT
How about the power and resources used to make them? Efficiency of the end product must be cancelled out by the power and mess caused by making them. I recall that many years ago a Range Rover had lower lifetime (including manufacture and disposal) emissions than a Prius. Likely still the case. |
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