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Post by zanygame on Feb 13, 2024 17:43:06 GMT
Are you aware of how a heat pump works? You can slam it into reverse so it heats up the battery. So are we putting heat into the car to stop the occupants from freezing or putting heat into the battery to enable it to be recharged?. Why not fit 2 heat pumps? - they could be powered by the trailer carrying all the extra batteries... there's a plan.. Same pump. When you put it on charge the heat pump warms the battery (Assuming the car hasn't been used and the battery is cold) When you drive it switches to heating the occupants. New heat pumps put 3.5 times more energy out than you put in. 1 kwh in 3.5kwh out. My older ones about 2.5 times. |
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Post by Orac on Feb 13, 2024 18:04:38 GMT
Where does it draw the heat from?
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Post by Pacifico on Feb 13, 2024 18:33:46 GMT
So are we putting heat into the car to stop the occupants from freezing or putting heat into the battery to enable it to be recharged?. Why not fit 2 heat pumps? - they could be powered by the trailer carrying all the extra batteries... there's a plan.. Same pump. When you put it on charge the heat pump warms the battery (Assuming the car hasn't been used and the battery is cold) When you drive it switches to heating the occupants. New heat pumps put 3.5 times more energy out than you put in. 1 kwh in 3.5kwh out. My older ones about 2.5 times. Heating the battery to allow it to charge also automatically works when you are driving in cold weather and input a charging station as your destination. |
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Post by zanygame on Feb 13, 2024 19:23:08 GMT
Where does it draw the heat from? The air. It cools a fluid by decompressing it to minus 15 degress pases it through a radiator where is absorbs heat from the warmer air (anything warmer than minus 15) it then compresses the fluid which heats to plus 40 degrees and passes through a second radiator in the car/ house giving off its heat. It then decompresses again and repeats |
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Post by zanygame on Feb 13, 2024 19:25:17 GMT
Same pump. When you put it on charge the heat pump warms the battery (Assuming the car hasn't been used and the battery is cold) When you drive it switches to heating the occupants. New heat pumps put 3.5 times more energy out than you put in. 1 kwh in 3.5kwh out. My older ones about 2.5 times. Heating the battery to allow it to charge also automatically works when you are driving in cold weather and input a charging station as your destination. Not quite sure what you mean, but yes, when the battery is taking demand it gets warm. |
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Post by Orac on Feb 13, 2024 20:03:48 GMT
Where does it draw the heat from? The air. It cools a fluid by decompressing it to minus 15 degress pases it through a radiator where is absorbs heat from the warmer air (anything warmer than minus 15) it then compresses the fluid which heats to plus 40 degrees and passes through a second radiator in the car/ house giving off its heat. It then decompresses again and repeats Yes. I know how a refrigerator works. I was asking where specifically where the heat comes from -- 'the air' is a bit vague. The air outside the car, the air inside the car? The reason I ask is because we seemed to be presented with the notion that a heat pump would be used to pump heat from the battery to warm the car. |
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Post by zanygame on Feb 13, 2024 20:56:35 GMT
The air. It cools a fluid by decompressing it to minus 15 degress pases it through a radiator where is absorbs heat from the warmer air (anything warmer than minus 15) it then compresses the fluid which heats to plus 40 degrees and passes through a second radiator in the car/ house giving off its heat. It then decompresses again and repeats Yes. I know how a refrigerator works. I was asking where specifically where the heat comes from -- 'the air' is a bit vague. The air outside the car, the air inside the car? The reason I ask is because we seemed to be presented with the notion that a heat pump would be used to pump heat from the battery to warm the car. Sorry, my mistake. I thought it was a loaded question, but treated it as genuine. From the air outside, as I say minus 10 is warm to a heat pump. As far as I know pre heating the battery is only done when the car is connected to the mains. |
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Post by Dan Dare on Feb 13, 2024 21:54:47 GMT
Zany is of course absolutely correct. In an EV the heat pump extracts energy from the ambient air to pre-heat the battery and then once the vehicle is charged and in operation uses the surplus heat from the motor(s) and the battery to warm the interior and the occupants. If you program it do so and the vehicle is plugged in and is charging it will pre-heat the cabin while you are still having your Shredded Wheat or Coco-Pops.
You could of course derive the same benefit by starting your ICE vehicle and leaving it running on the driveway for half an hour or so.
There's no great mystery or sinister plot behind any of this.
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Post by Pacifico on Feb 13, 2024 22:21:52 GMT
Heating the battery to allow it to charge also automatically works when you are driving in cold weather and input a charging station as your destination. Not quite sure what you mean, but yes, when the battery is taking demand it gets warm. On a Tesla (and some other brands) if you input a supercharger in the satnav and the outside temperature is low then the car will automatically switch on the battery heater before you reach your destination. That way the battery is warm enough to charge when you get to your destination - of course the heaters draw power from the battery and thus reduce your range. |
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Post by zanygame on Feb 13, 2024 22:24:26 GMT
Not quite sure what you mean, but yes, when the battery is taking demand it gets warm. On a Tesla (and some other brands) if you input a supercharger in the satnav and the outside temperature is low then the car will automatically switch on the battery heater before you reach your destination. That way the battery is warm enough to charge when you get to your destination - of course the heaters draw power from the battery and thus reduce your range. Interesting. I guess if you have range then you can make the choice. |
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Post by Orac on Feb 14, 2024 0:19:50 GMT
Yes. I know how a refrigerator works. I was asking where specifically where the heat comes from -- 'the air' is a bit vague. The air outside the car, the air inside the car? The reason I ask is because we seemed to be presented with the notion that a heat pump would be used to pump heat from the battery to warm the car. Sorry, my mistake. I thought it was a loaded question, but treated it as genuine. From the air outside, as I say minus 10 is warm to a heat pump. As far as I know pre heating the battery is only done when the car is connected to the mains. It was genuine question because someone presented the notion of heat pump taking heat from the battery to heat the car. This is bonkers, but i couldn't exclude it entirely because it might just pass muster as a gimmick for an EV buyer. I think your predictions about minu 10 ect are optimistic - I doubt the kind of heat exchanger you could sensibly fit in a car could get much (any) advantage out of minus 10 |
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Post by Dan Dare on Feb 14, 2024 6:01:04 GMT
It was genuine question because someone presented the notion of heat pump taking heat from the battery to heat the car. This is bonkers, but i couldn't exclude it entirely because it might just pass muster as a gimmick for an EV buyer. Not bonkers at all, that's exactly what happens at least in a Tesla (I assume also with other BEVs that have heat pumps).
From the Model Y owner's handbook:
"...You can improve the efficiency of the cabin heating by reducing your selected acceleration mode (see Acceleration Modes on page 84). This allows the heat pump system to take more heat from the Battery to efficiently heat the cabin, instead of maintaining the Battery's ability to provide peak acceleration performance. This helps to maximize driving efficiency in colder weather."
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Post by jonksy on Feb 14, 2024 7:51:07 GMT
Car dealers slash EV prices by up to a QUARTER in frantic bid to stimulate sales...... With demand for electric vehicles stalling in Britain, car dealers across the country are being forced to slash prices in a desperate bid to shift their existing stock. The average discount on a new EV has increased by 204 per cent since last January, according to market analysis by What Car?, as dealerships are going to extraordinary lengths to stimulate sales.
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Post by Pacifico on Feb 14, 2024 8:09:26 GMT
It's going to be interesting - no EV manufacturer is making money on building and selling cars at the current premium prices we have seen. If they are now in a price war for market share I think we will see a fair few go under in the coming years.
The US already has restrictions on cheap Chinese cars and it looks like the EU is going to follow suit - which is not helping the Chinese economy which looks to now be trapped in a deflationary spiral..
..interesting times..
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Post by Orac on Feb 14, 2024 8:24:43 GMT
It was genuine question because someone presented the notion of heat pump taking heat from the battery to heat the car. This is bonkers, but i couldn't exclude it entirely because it might just pass muster as a gimmick for an EV buyer. Not bonkers at all, that's exactly what happens at least in a Tesla (I assume also with other BEVs that have heat pumps).
From the Model Y owner's handbook:
"...You can improve the efficiency of the cabin heating by reducing your selected acceleration mode (see Acceleration Modes on page 84). This allows the heat pump system to take more heat from the Battery to efficiently heat the cabin, instead of maintaining the Battery's ability to provide peak acceleration performance. This helps to maximize driving efficiency in colder weather."
There you go. |
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