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So… Highland is out…
- Thread starter boombap
- Start date
It is uncommon in the US to have privacy glass in a saloon as the boot is not exposed to outside. So Model 3 rocked up without it and Model Y had it. I don’t expect this to change with the highland model.
LiamPope
Member
I missed the video link between responses somehow, so will take a look - thanks. I certainly haven't heard any feedback, especially here in Norway where we have plenty of cold mornings and short trips to childcare/work, of a heat pump car being less efficient than an old resistive heater car for this usage. Interesting topic (or should that be off-topic!)
Zilla91
Active Member
But it's not in Europe or elsewhere outside of North America. Since these markets are supplied from Shanghai there's really no reason why it's not done other than pure laziness on Tesla's part.
Your previous thread has those discussions, so I do not want to repeat again including the laziness from Tesla.
Why does the Model 3 not have privacy glass?
It's one thing that really bugs me about my M3P, why does it not come with privacy glass like the Model Y does? Makes no sense to me and I've never found an explanation why
teslamotorsclub.com
Funnily enough today I saw a Model Y in Cambridge without privacy glass at the back..
So I’ve not watched this video but have seen Tesla Bjorn’s videos on this and it’s never pulled close to what you’re suggesting even when he’s in like -20C. Also Out of Spec have done something on this also.
My wife’s car can heat up or cool down in 2 - 3 minutes max from whatever temp the UK can throw at it. I just don’t believe when there’s so much evidence that they are vastly more efficient all over the Internet that it actually isn’t.
bay74
Member
Hi GlynG.
Keen to hear if I'm misunderstanding something. Cheers.
I think it is an air source heat pump. It's 'pumping' heat from the outside air into the cabin (or vice versa); heat which is transferred into (out of) the vehicle initially (finally) through the radiator. Yes it can also pump heat from other sources like the motors and battery, in an attempt to increase efficiency, but if they are cold then this won't happen.
The power draw of the heat pump depends on what is being asked of the system, not solely on the exterior temperature. While it may be able to draw up to 7.5kW, it certainly doesn't have to be doing so (like an old-school air conditioner). Presumably you meant "When you first start driving and the cabin's cold and you turn the heat up...".
There's a logic failure here. So what if the heater / AC can use 7.5kW - why does that mean we need a larger battery? The heat pump is more efficient than a resistive heater (in cabin heating mode) so you will use less energy in cold conditions than in the older cars, so you'd expect increased range even if the battery were the same size.
The heat pump can't be less efficient, that's basic physics; therefore I would suggest that the only way this could be true is if the cars with heat pumps were heating more than just the cabin - perhaps they're heating the battery as well as the cabin whereas the resistive heater cars were just driving around with a cold battery (I'm not sure under which conditions the pre-heat-pump cars try to heat the battery using the motors, other than when navigating to a Supercharger).
I disagree that the most significant source of heat is the motors. More likely, it's the external radiator - unless you're on a race track perhaps. One could argue that heat produced is indeed greatest in the motors - if you call converting electrical energy into heat "production", and hence disregard the transfer of heat from ambient air into the radiator. But that's an irrelevant technicality because (I attest) heat gathered for use by the heat pump will still be dominated by the radiator. What's the efficiency of the motors? 95%? Now at freeway speed we're using about 15kW (very roughly; 350km range from ~50kWh over ~3.5 hours). The electrical losses (and hence heat generated) is therefore about 750W. That's not nothing but certainly well below the potential output of the heat pump (and PTC heater), and likely below cabin heating requirements in cold weather.
Keen to hear if I'm misunderstanding something. Cheers.
LiamPope
Member
OK I watched the video! And a bunch more. I have to say - to anyone remotely interested in engineering, the whole long video is absolutely worth watching - fascinating! To address a couple of your points though...
First - it absolutely is an air sourced heat pump! The video goes into detail around 15:50 about how ambient air, drawn through the radiator, is one of the primary energy sources. So in that sense it really is very much like a domestic heat pump, which was my original comment on the topic ('surely it works like a normal heat pump?'). But of course it's so much more - it's a multiple source heat pump. And just how many sources was the fascinating part of the video - almost any heat generating process you can imagine in the car can be harvested by the system - amazing engineering!
Second - you say at 10C it is consuming 7.5 kW and is less efficient than the old resistive PTC system. I honestly don't know how you got that from the video! 10C is, according to the guy in the video, just the temperature below which they may start to use the 'lossy' resistive heat generation sources if needed to boost output from other sources. But if it actually uses any of these sources or not depends on the demand - he showed a demonstration of the car at standstill, plugged into a rapid charger, pre-heating the battery for rapid charging. But that's a very specific scenario where you don't care much about energy consumption and just want to heat the battery as fast as possible, so of course you'll throw everything at it, hence you see 6 kW resistive heat from the drive units being generated.
But just heating the cabin at a balmy 9.5C ambient won't need anything more than the ambient air source heat pump. In fact that won't be too far off the sweet spot for the air source heat pump (or any air source heat pump worth its salt) - Tesla claim up to 5.6 peak COP, which most probably includes maximum contribution from the other 'free' sources. Even on a cold start/short trip at 10C with no extra sources initially available, the air source heat pump will be something like COP 3-4, so way more efficient than PTC (always effectively COP=1).
So if it's way more efficient than PTC at 10C, even standing still or a short trip, the performance certainly doesn't fall off a cliff anything below 10C and somehow become less efficient than a PTC! Tesla Bjørn did some testing with PTC and heat pump Model 3s at 3C just standing still and maintaining cabin temp. The heat pump car consumed a bit over a third the energy of the PTC car, suggesting a COP almost 3 at 3C, which doesn't sound unreasonable at all.
You'd have to go down way below zero for the air source heat pump circuit COP to get down near 1. Even when it does, it has now reduced to the same efficiency as a PTC system. There is literally no possible situation when it is less efficient than PTC - that's not possible! Even if it's so cold the air source part is useless and it runs entirely on the lossy generation sources it is running at COP=1 and is equivalent to a PTC system.
So, quick summary - at 10C the heat pump is a good few times more efficient than PTC, even cold start/short trips, not consuming 7.5kW as you say. It's never less efficient than PTC! And that is all in line with all the tests and owner feedback I have seen. Amazingly engineered system - the functionality and integration/packaging is incredible - a genuine example of where Tesla really did embarrass the competition, no bs.
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I've not read the full thread, nor watched the video, but at the time it came out I was very much under the impression the whole point of the Octovalue thing was to have multiple options in harvesting/cooling and heating of multiple components. It may have an air source option, but it also has others, and taking heat from a hot motor may be a better option than cold air at times, it may be taking heat out of the battery when supercharging, or putting heat into the battery to precondition. It may be heating the cabin, or it may be cooling the cabin
I'm not sure its worth falling out over or side tracking a thread on the highland to talk about a component that is in all Teslas built today.
I'm not sure its worth falling out over or side tracking a thread on the highland to talk about a component that is in all Teslas built today.
LiamPope
Member
Absolutely correct.
Also correct!
Claims were made about the heat pump that were so out of whack with my understanding I had to question it and look deeper into it. Glad I got to the bottom of it, helped dispel some incorrect information, watched a very interesting bunch of videos, and now willing to steer back on path! 
Exactly… there’s no choice … you can’t have a Highland, or any other recent Tesla with a different heating/cooling system. At one time I speculated that the PTC heater might be a bit faster bringing the car to temperature but that was disproved too!
It has been seen in practice that the heat pump cars operate more efficiently. That’s really all we need to know.
Anyway, the system is clearly “state of the art” and well worth the accolades that come Teslas way whenever any serious engineer takes a look at it.
They must have replaced with clear glass as Model Y comes with privacy glass. I will look out for that Model Y.
In other news came across something that's a bit old but talk of a different motor for the Model 3 Performance. It won't be a Plaid sadly but it might get a Plaid rear carbon wrapped rotor. The issue is those motors are only made in the US so maybe they are building a line to make them in China but it's not ready yet.
I guess if just one rotor is wrapped it'll lose power at higher speeds from the front but the rear should be stay solid so it'll be an improvement. The Plaid motor though isn't a hairpin design so not quite as efficient. Also wonder if any battery change as the LG battery would be limiting.
So not a tri motor Plaid but still a noticible performance bump.
I guess if just one rotor is wrapped it'll lose power at higher speeds from the front but the rear should be stay solid so it'll be an improvement. The Plaid motor though isn't a hairpin design so not quite as efficient. Also wonder if any battery change as the LG battery would be limiting.
So not a tri motor Plaid but still a noticible performance bump.
I also read somewhere that they’re unlikely to use the plaid motors because of the packaging constraints. They couldn’t make a RHD MS with the motor as they couldn’t fit in the steering rack, and the M3 would have even less room. That said they fit in two at the back. Maybe it’s to do with weight distribution, but whatever, I dare say the usual Twitter suspects will produce a lot of speculation while we wait for the truth
bkp_duke
Well-Known Member
Has nothing to do with packing constraints in the S for RHD. There is plenty of room for the carbon wrapped motor, which is smaller than the old motor it replaced.
And yes, should they choose, they could put that motor in a 3.
Well thats at odds with pretty much everyone including a number of Tesla staff for thinking that. I kind of think people in the RHD markets may have followed the RHD story closer than someone who's not.
One guy even told me that they looked at introducing a MS+ rear wheel drive only version a bit like the the old P85+ but that was ruled out due to the small numbers.
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