WDB
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Post by WDB on Jun 21, 2023 12:54:35 GMT
We are told driving with the windows open is very inefficient with ICE, looks the opposite with EV. I don't think 'opposite' is the right word here. I suspect you'd see the same effect with an ICE at low speeds - lower than the speed where air resistance becomes the greatest opponent to motion and open windows become a real drag - if you could isolate it. It's just that the CC in an ICE car is a proportionally smaller drain, because its absolute energy consumption is about the same as in an EV, assuming two similar-sized cars. The EV is wasting so little energy at low speeds that the consumption of ancillaries is very noticeable. |
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bpg
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Post by bpg on Jun 21, 2023 13:10:15 GMT
I used the word opposite in the sense we are advised driving an ICE car with the windows open creates drag which increases cost.
Running aircon in an EV increases cost over driving around with the windows open so the advice would be to drive with widows open to keep cool and reduce cost indicating the opposite is true of an EV when comparing with an ICE.
Your point regarding the relative costs of running aircon in either vehicles being fairly constant remains true and the efficiency of the electric motor/generator simply amplifies the other costs in motoring which have been ignored to date.
Sweat absorbing, removable and washable, hemp seat covers and aircon delete anyone ?
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WDB
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Post by WDB on Jun 21, 2023 13:37:12 GMT
...the advice would be to drive with widows open to keep cool and reduce cost indicating the opposite is true of an EV when comparing with an ICE. If that is the advice for ICEs, then (like a lot of such advice  ) it's simplistic at best. In either type of car, you can generally afford to have the windows (and the widows  ) open up to about the speeds in your test. (I quite often do in either car, especially if it's full of hot air from standing in the sun.) But above that, you'll be creating unnecessary air resistance, which EVs and fossils suffer from equally, and you'll do better (and have a much quieter ride) if you keep the exterior smooth and cool the air artificially. A faster-moving car also benefits from the ram effect of incoming air, which gives the coolers less work to do, assuming most of what you're working against is solar gain through the glass rather than truly hot external air. I won't be deleting the CC from my next EV just yet! |
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Post by EspadaIII on Jun 21, 2023 14:43:59 GMT
Even with a heat pump, winter range in my car is about 70% of summer range. Don't think that AC has much effect on the range in the summer, or it's not very noticeable.
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Post by Humph on Jun 21, 2023 14:47:29 GMT
I mean, I can see that these electric things are getting better. I’ll maybe have a go at one once they’re y’know sorted.
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bpg
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Post by bpg on Jun 21, 2023 15:23:54 GMT
(I quite often do in either car, especially if it's full of hot air from standing in the sun.) But above that, you'll be creating unnecessary air resistance, which EVs and fossils suffer from equally, and you'll do better (and have a much quieter ride) if you keep the exterior smooth and cool the air artificially. A faster-moving car also benefits from the ram effect of incoming air, which gives the coolers less work to do, assuming most of what you're working against is solar gain through the glass rather than truly hot external air. I won't be deleting the CC from my next EV just yet! Opening the windows às you drive off or opening all the doors before you get in for a few minutes always helps the aircon out. Never heard of ram air being used for HVAC, probably too much faff requiring vents and shutters for winter, quite common on motorbikes with specific air intakes placed to maximise forced ambient air intake, hopefully with an additional cooling effect, without resorting to turbochargers and intercoolers. I suppose performance cars will have a similar setup but no one really shouts about it. |
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WDB
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Post by WDB on Jun 21, 2023 15:44:17 GMT
Even with a heat pump, winter range in my car is about 70% of summer range. Don't think that AC has much effect on the range in the summer, or it's not very noticeable. I can understand how it might in the case that bpg describes, at low speed with the motor doing very little and the AC being the biggest ancillary in use. Heat pumps do seem to be a bit of a mixed bag: the theoretical case in favour is clear but I'm not sure I can back it with anecdotal evidence from my own cars. Perhaps it matters what cabin temperature you select. I tend to be happy with 17ºC and keeping my jacket on, and perhaps I'd notice more benefit if I was asking for T-shirt temperature as I imagine some users do. A YouTube film I saw the other week pitted one plain i3 against another with a heat pump at 21ºC and did find an improvement, although still not a huge one. Winter range does seem to depend more on battery thermodynamics than cabin heating hardware - although even a 5 percent improvement in range could make the difference between getting home without a stop and not. |
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bpg
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Post by bpg on Jun 21, 2023 15:59:24 GMT
I've found with the EV set the temperature no more than 5°C below the ambient temperature after driving off with all windows open to dump the excess heat. It will achieve that temperature. SUV = greenhouse on wheels.
My petrol and diesel are both usually 21°C all year round. The EV is set to 23°C. That sounds high but it works.
Another recommendation I've read is not to have more than 10°C variance between aircon temp and ambient. Can cause medical issues going from say 17°C to 30-something degrees with the opening of a door.
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Post by EspadaIII on Jun 22, 2023 3:05:26 GMT
Every car with climate control I have owned has required a different nominal termperature. My Outback needed 23 on the display, the S-Max it was 21, the Mercedes it was 20 and in the I5 it is 20.5. 21 in the I5 is too warm an 20 is too cold.
I have never understood the need to have AC in the summer at 17 or 18. Way too cold. The real benefit is dehumidification which can be achieved at far higher temps.
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WDB
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Post by WDB on Jun 22, 2023 10:23:04 GMT
Yes, it’s not a scientific instrument so the calibration will vary, Even between examples of the same type. Different types also distribute the air differently — CLS even lets me choose Diffuse, Focused or, erm, something else (I like Diffuse) — which will also affect the apparent temperature.
17°C for me in the i3 is the winter cabin temperature. I’m happy to keep it at 21 in warmer weather.
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Post by dixinormus on Jun 29, 2023 1:05:41 GMT
There seems to be a global recall for the i-Pace kicking off? I wonder how efficient JLR will be in carrying it out.
Meanwhile owners are being advised “Until the recall has been completed, clients should park away from structures where possible and charge the vehicle outside”..!
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WDB
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Post by WDB on Jun 29, 2023 6:01:26 GMT
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bpg
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Post by bpg on Jul 14, 2023 6:46:51 GMT
Coming back from an early morning airport drop off I came up behind a brand new Nissan Qashqai e-somethingorother.
It was quite brisk (compared to my 12 year old diesel) for an SUV until aerodynamics took over, then it just got in everyone's way. I'd never seen one before so looked it up, boy have Nissan come up with Al's dream tech used car 5+ years down the line.
1. It's around 190hp electric motor only drive to the front wheels off a 2.1kWh battery.
2. It uses a 1.5 litre 3 cylinder turbocharged petrol engine with variable compression. That is not a typo, not variable valve timing, variable compression.
3. You can't plug it in, all electricity comes from burning petrol.
The reasons I said it's Al's dream tech car:
2.1kWh battery constantly charging and discharging especially the way the one I followed yesterday with the binary accelerator button use cannot be good for it. The BMS must bypass the battery with the petrol engine feeding the electric motor directly for such use.
The variable compression, something I don't think we've seen in a mass produced car before. I know SAAB tinkered with it for a good few years, don't think they got to market with it. The pistons are not connected to the crankshaft via the usual conrods but opt for a series of motors to vary TDC and BDC and stretch the capacity. Very clever engineering, wonder how sensitive it will be to missed services/oil changes.
Nissan claims it's a stepping stone to full EV and people don't plug hybrid cars in. Toyota said hybrid was all the car people need and they wouldn't build a BEV, enter the catchy titled bz4x. Not knocking anyone just showing how new all this is with the big players still finding their feet.
The inertia (or lack of) idea could well be the way to go.
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Deleted
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Post by Deleted on Jul 14, 2023 7:40:19 GMT
OK, you've completely lost me there! No idea why that's my dream tech car, but if it was good enough for SAAB then why not.
All I really want is an EV which will do a minimum 250 miles in all the weather conditions that the mainland (except the Scottish Highlands in extremis) UK can throw at it. Which (ideally, but not compulsorily) isn't Chinese or a Tesla.
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WDB
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Post by WDB on Jul 14, 2023 7:45:28 GMT
OK, you've completely lost me there! No idea why that's my dream tech car… Because it’ll be a maintenance nightmare in ten years’ time? A BMW i4 might fit those criteria, Vić. I can’t get in the back, but it’d be your car so I wouldn’t have to. 🤓 |
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) it's simplistic at best. In either type of car, you can generally afford to have the windows (and the widows 
) open up to about the speeds in your test. (I quite often do in either car, especially if it's full of hot air from standing in the sun.) But above that, you'll be creating unnecessary air resistance, which EVs and fossils suffer from equally, and you'll do better (and have a much quieter ride) if you keep the exterior smooth and cool the air artificially. A faster-moving car also benefits from the ram effect of incoming air, which gives the coolers less work to do, assuming most of what you're working against is solar gain through the glass rather than truly hot external air.
