Pre-Departure Climate Control

[garygid]

A feature that Aptera could possibly provide, probably with
just a little programming: a "Pre-Departure Climate Control"

One could specify that the climate control system should
turn on at a chosen time, with a set temperature target,
and possibly stay on for a user-specified length of time.
Basically, a programmed thermostatic control.

This would be very nice to get the Aptera comfortable to go at
some "expected" departure (like go-to-work, or go-to-school) time.
If the Climate Control runs in the morning while the Aptera is still
plugged into the charger, one could still leave with "topped-up"
batteries, and be nice and warm, or nicely cool.

If the climate control system is already controlled by
the car's computer, then it should be an easy feature
to provide with a software upgrade after production begins.

Do you like it?

[GCustom]

like the pre-conditioning of the previous generation of EVs?

[Chupacabra]

I thought thats what it already had, not regulated by time, but operating off the solar cells on the roof it would keep the cabin at whatever temperature you decide.

[garygid]

The solar cells will not work at night, in the garage, or in a
carport. Even when in sunlight, I suspect that they can generate
only enough power to run a "fresh-air" fan, not nearly enough
energy to run the whole climate control system, even a little bit.

For example, take a cold morning, just after the sun comes out,
and it is still 40 or 50 degrees outside. If the fresh-air system
starts ventilating blindly, it would make sure that the cabin is
"too cold".

[panamericans]

Great Idea Gary, but first things first… It would be nice to know what the specs are on the heat pump Aptara plans to install. Knowing this would answer a number of questions… One of which would be the feasibility of fixed windows…. i.e. what heat load can the pump carry using the solar cells on a hot day.

mpk #1456

[LQUAN]

Unfortunately, with such small solar pannel, the only type of heat dump system you can have is a couple of fans to draw hot air from inside the car to outside. It cannot possibly run a full blown AC system with compressor and condenser. As the air inside the car gets heat up, so will the upholstries, dashboard, interior moulding, etc. This is why after parking your car under the hot sun, you turn on the AC, after half an hour later the car is still hot as soon as you turn off your AC even when your car is no longer under the sun. That's because your interior upholstries, carpet, and mouldings are still giving off heat. Those things retain heat very well. Air can get cool down very quickly with the AC, but not the upholstries. This why without rolldown windows to disipate heat retained by the interior stuffs quickly for the AC to work efficiently, you will be cooking in your car for a while even with the AC running full blast.

[garygid]

Estimating ...
1. "average" Solar radiation to be about 1000 watts per square meter
2. Panel area of about 1 foot by 3 feet ... about 0.3 square meter
3. Solar-voltaic efficiency, about 20%

So, about 1000 x 0.3 x 0.2 => something around 60 watts.
However, I suspect that this is an overly optimistic estimation.

For comparison, the AZM 50W SOLAR PANEL (http://sector29.com/PRODUCT_PAGES/133/133-354-5ef6a6a90e97164c0cba245e8cfe3719.html) is only rated for
50 watts, and seems to be about 50% larger (roughly 17" x 40").
Also, its cells also cover the whole surface, rather than the (perhaps
80%) coverage of the circular solar cells seen on the Aptera prototype.

So, as another estimate, 2/3 of 80% of 50 watts ... about 26 watts.

I suspect that 25 watts is a better estimate for the Aptera's
solar panel, but I am really just guessing.

Now, perhaps wanting heating or cooling at at least a 600 watt rate,
would take about 200 watts of power consumption for an efficient heat
pump. A 1200 watt heat pump might require 400 watts to drive it.

And, if you are trying to cool, and the outside is already quite hot,
the heat pump efficiency will drop off.

So, it is not likely that the rooftop "25 watt" power source will be able
to run any "reasonable" capacity heat pump climate control system at all.
Presumably, it will only run a fan to "ventilate" the cabin.

[panamericans]

Gary,

You must have seen the video where Chris Anthony is expounding the virtues of the Aptera.

In particular, he mentions that when one parks the car in the hot sun the vehicle will be cooler then the outside ambient temperature. He specifically mentions cooling to 75 degrees when it is 120 degrees outside.

Now either he is 'blowing hot air', or Aptera just might have an interesting heat pump arrangement. I don't understand why Aptera Motors would want to exaggerate such a claim?

mpk #1456

PS: I am not doubting your numbers but just curious about this feature?

[LQUAN]

I am afraid Chris is just blowing hot air...

Think about it. If the outside air temperature is 120F, the car is drawing outside air and pumps out inside air. What temperature would the inside gets if there is not AC to cool down the outside air?

For crying out loud, my wife used to live in Palm Desert when we were still dating. Typical summers temperatures in Palm Desert is 112F to 120F. Her brandnew Lexus GS300 AC system couldn't even bring the interior temperature down to 75F running full blast. And she used to park inside a cool coverred garage everytime before we departed.

[hyo silver]

That's an interesting idea, Gary. With inside and outside temperature indicators, software could operate the vents and fans to achieve the desired temperature. Depending on the situation, cooler or warmer air could be drawn inside. A button on the remote could be activated before departure to 'preheat' or cool the cabin as necessary. Assuming the car was plugged in, there'd be enough power to cool below the usual 75F that can be achieved with vents alone. Also, some kind of photochromatic glass could make a significant difference to the solar heat gain.

[LQUAN]

There are many confusions about HEAT PUMP. Maybe someone can better define what is a HEAT PUMP. My understanding of a heat pump is just fans removing hot air or drawing hot air source from one place to another. Anyone?

Please don't confuse HEAT PUMP system with AIR CONDITION system. AC use Freon. Heat pump does NOT.

[garygid]

I suspect that Chris might have been confusing two issues:

1. Use of the cooling by the heat pump (which would be really
nice, and not impossible, but it would probably take battery
power to run ... and I think it should be an available feature).

2. Circulation of outside air through the vehicle.

If he was talking about #2, then he might have meant to say that
even when the outside air temp is 70, the closed, unventilated
cabin (in the sunshine) might heat up to a "baking" 130 degrees.
However, with the fresh-air system running, the cabin might stay
much closer to the ambient 70-degree outside air temperature.

However, if he was talking about #1, then it is a feature that has
not yet been very well described. What do they intend to do?

Who knows?

[garygid]

A heat pump is an air conditioning system, just like one that
you would put in the window of a house.
Yes, it does use a refrigerant, like freon or some other.

The one for automotive use is exactly the same, just scaled
down a little to use less electricity, take less room, and weigh less.

[LQUAN]

I think those who expect a heat pump that uses freon for cooling while parking, you will be disappointed.

What Gary said...

"If he was talking about #2, then he might have meant to say that
even when the outside air temp is 70, the closed, unventilated
cabin (in the sunshine) might heat up to a "baking" 130 degrees.
However, with the fresh-air system running, the cabin might stay
much closer to the ambient 70-degree outside air temperature."

makes sense. But if the outside temperature is baking at 120F, don't expect the inside temperature of an enclosed car is any less than 120F with the use of a refrigerantless air circulating system.

[gistmarrs]

A heat pump is basically a typical air conditioner that can be reversed to produce heat also. It still uses a refrigerant to create the phase change which produces the differential temperature. They can be made any size and I suspect one to cool an Aptera that would be running all of the time could be quite small. However, there looks to only be about 5 sq.ft. of panels on the roof and that will only produce about 60 watts or roughly 600 BTU/hr of cooling.

Let's say the surface area is about 150 sq.ft. for the Aptera and we want to keep a 20degF delta temperature in the car. If I'm not mistaken, the entire car will have to average an R-value of about 5. R=degF X sq.ft. / BTU/hr.

[davidrools]

I strongly suspect that this "Chris" is being misquoted or misunderstood and that the likely scenario is Gary's #2. A 120ºF ambient temperature is very rare and would only occur on an extremely sunny day, which, as it turns out would provide more power to the solar panel! If the solar panel were more practical than gimmick (which I hope and expect it to be), it was sized for the specific application of cooling to a comfortable temperature. Less sunlight, less heat, less power, but still enough to cool slightly. Bright sunlight, more heat, more power, more ability to cool sufficiently.

If not running a heat pump, thermoelectric cooling and resistance heating could be employed for a light weight, easily packaged, modular means of climate control, although the cooling side would be rather inefficient. Regardless, any means of cooling requires heat dissipation into an already hot outside body of air and you can only expect so much. But with full time circulation, the load drops considerably as opposed to what's required to cool a conventional car after baking in the sun.

[Hybrid762]

Whatever they design will be better than any current car has. Even if the car only cools 10 degrees less than outside is better than nothing. Too bad the solar panels couldn't be used to charge the Aptera no matter how little it supplied energy to the battery.

[Chupacabra]

However their solar panel works, it would be cool if while its plugged in and topped off it could use the juice from the plug to power the ambient temp system.

[garygid]

Yes, indeed, have the Climate Control work (when desired)
when plugged in, and also when NOT plugged in, and one is
willing to "spend" some of the battery on cooling because
one is anticipating returning to the vehicle in a "short" time.

[KarenRei]

Now, perhaps wanting heating or cooling at at least a 600 watt rate,
would take about 200 watts of power consumption for an efficient heat
pump. A 1200 watt heat pump might require 400 watts to drive it.


A COP of three?

He specifically mentions cooling to 75 degrees when it is 120 degrees outside.

I remember the quote as being something along the lines of, "So, when you get back to your car, it's 75 degrees inside instead of 120". I.e., it's ~70 outside, and if you hadn't been running air through your car, it'd be 120 inside due to the greenhouse effect.

[3-4-me]

A COP of only three? Surely it'll be better than that!



I remember the quote as being something along the lines of, "So, when you get back to your car, it's 75 degrees inside instead of 120". I.e., it's ~70 outside, and if you hadn't been running air through your car, it'd be 120 inside due to the greenhouse effect.

I just saw that video again, you're right Karen.

[panamericans]

I haven’t a clue what Aptera did with their heat pump arrangement and yes, I do wish I knew more. I do know that these units can be made small or set to different load settings. It is also true on a hot day, provided the car wasn’t subjected to the sun’s rays before hand, then the heat load is humongously reduced for any system to cope with… I do suspect that the system can turn under reduced power and still keep the car from turning into a vehicle from hell that can seat two. I do wonder?

Once a car attracts a heat buildup, air conditioning is ineffective for a substantial part of the journey. Actually it can make the situation worse…i.e. hot car tangibles and cold air drafts are not a comfortable mix.

mpk #1456

[n_dawg]

There seem to be a bunch of misconceptions about the Aptera solar climate control going around.

Firstly, the contention that the solar panel would be unable to power a heat pump to cool the Aptera. Let's examine this:

Assuming that the solar panel is 18 inches by 36 inches and 20% efficient, that would provide about 83 watts of power. Assuming a CoP of 4 (not unreasonable), that would be capable of 334 watts of cooling. Assuming the windshield is 5 feet by 3 feet, it would absorb 1400 watts of solar energy. It would seem to be game, set, and match for cooling.

However, we're forgetting infrared coatings. Almost 1/2rds of the solar spectrum (http://en.wikipedia.org/wiki/Image:Solar_Spectrum.png) is in the infrared. Low-E coatings reflect infrared radiations while allowing visible light. We've just cut our cooling needs in half, down to a more manageable 700 watts, only 360 watts away from what's available.

Sounds like less than "one or two degrees above ambient temperature"(source (http://www.gizmag.com/aptera-typ1-three-wheel-electric-vehicle/8392/3/)) to me.

Oh, and why do I think the solar power runs the heat pump? They say so!

"The solar assisted climate control … simply takes solar energy from the solar cells embedded into the roof to power the normal climate control system."(source (http://aptera.com/))

[garygid]

Assuming
1. your estimates are correct, and
2. the windshield is the only source of heating, and
3. that Aptera uses an IR reflective film on the windshield, and
4. the film is 50% reflective of the incoming energy ...

334 watts of cooling does not begin to keep up
with 700 watts of heating, right?

1. There will be heating through the body, and through the other
windows, both by incoming radiation, and conductive.
So, the heat coming in could easily be double 700 watts.

2, Seems to me that the heat pump Climate Control system
has to be capable of a lot more cooling than 334 watts.
If not, the cabin could become ... uncomfortably warm.

3. Right now, I cannot find an "official" written description
on the Aptera site of a "fresh-air ventilation system".
Is that just a misconception or a myth?
I thought it was mentioned in other places.

[KarenRei]

However, we're forgetting infrared coatings. Almost 1/2rds of the solar spectrum is in the infrared. Low-E coatings reflect infrared radiations while allowing visible light. We've just cut our cooling needs in half, down to a more manageable 700 watts, only 360 watts away from what's available.

Infrared coatings are used on greenhouses to make them *hotter*. While half of the energy of the sun is infrared, almost all of the energy radiating from the inside to the outside is infrared. Also, glass is already a pretty good IR absorber.

Perhaps coatings that specifically affect "near IR" (wavelengths close to visible light) but don't do anything to "mid IR" (what most thermal radiation on Earth is) would help. And if I remember right, glass mainly blocks mid IR, not near IR. So that would make sense.

[n_dawg]

Of course 700 > 340, but the goal here isn't to get the total heat transfer to 0. Aptera has said that it will keep the car less than 2 degrees above ambient, not that it won't heat up.

Yes there is conductive heating, but there's also radiant cooling (the interior isn't charcoal black, after all) So I think it's a wash.


To answer your question Karen, IR coatings are used in greenhouses. They can also be put on the other side of the glass to reject heat. It's one of those thin-film effects which depends on which way the radiation is going. If it wasn't, infrared wouldn't be able to get into the greenhouse!. http://en.wikipedia.org/wiki/Low-emissivity has an unsourced description.

[gistmarrs]

If the windshield were covered with one of those reflectors and the side windows were tinted, you might have a chance at keeping most of the radiant heat from entering the car and cool it below ambient. Low emissivity windows will also help quite a lot.

Thermal curtains are used in greenhouses to reflect longwave radiation at night back into a greenhouse to keep it warm, but infrared (low-e)coatings are typically not used and would do the opposite. Low-e coatings are only used for keeping the greenhouse cooler in the summer months in hot locations. FWIW, I worked for Monrovia Nursery designing their facilities all over the country for 14 years.

[KarenRei]

Thermal curtains are used in greenhouses to reflect longwave radiation at night back into a greenhouse to keep it warm, but infrared (low-e)coatings are typically not used and would do the opposite. Low-e coatings are only used for keeping the greenhouse cooler in the summer months in hot locations. FWIW, I worked for Monrovia Nursery designing their facilities all over the country for 14 years.

1) I used to be very active in the Gardenweb greenhouse forum and built several greenhouses.

2) Infrared coatings are plugged by a number of thin-film greenhouse manufacturers for retaining radiant heat; it's a common coating, along with ones for UV and humidity resistance. Not so much for polycarbonate and glass since they already absorb IR pretty well.

3) Longwave *is* IR. Long and mid IR are emitted in normal ambient temperatures (mainly long; I was thinking it was mainly mid, but I checked, and long is more common).

As I mentioned, a coating that blocks near-IR would make sense to keep things cool, but a general IR-blocking coating wouldn't. Example for you:

http://ag.arizona.edu/CEAC/research/archive/HortGlazing.pdf

Radiation heat losses are directly related to the physical properties of the cover material. These include the emissivity and the transmissivity (in the infrared and thermal wavebands) of the covering material. The emissivity is a material property which defines its ability to emit radiation energy that it has absorbed. Energy absorbed by the cover from inside the greenhouse and emitted to the outdoor environment as long wave radiation provides a heat loss from the greenhouse environment. The larger the emissivity, then the greater the rate of radiation heat loss. The transmissivity is a material property which determines its ability to transmit radiation energy. In this case, it is not the visible radiation which is of concern, but infrared and thermal radiation. This energy is directly transmitted by the cover from inside the greenhouse and it creates a heat loss from the greenhouse environment. The larger the transmissivity for infrared or thermal radiation, the greater the rate of radiation heat loss.

...

Additives incorporated into PE film reduce infrared radiation transmission. They absorb and re-emit infrared radiation from the greenhouse, thereby reducing heat transfer by radiation and improving the energy conserving capability of the film. A double-layer PE film tested at Rutgers University, later manufactured as "Cloud Nine" by the Monsanto Company (later CT Films, currently not in production), demonstrated a savings in nighttime supplemental heating of between 20% and 25% over the standard double-layer Monsanto 602 film for a single-bay, free-standing greenhouse (Roberts, et al, 1985). The energy savings was primarily a result of the IR absorbing film properties; however, it was also determined that an interaction with the hot air heating system contributed to this savings. The effect was a mean air temperature near the glazing (overhead) that was always significantly greater (1.7 OC, 3 0 F) for the non-IR film-covered greenhouse than for the greenhouse with the IR barrier film. This occurred because the heater required more frequent operation in the non-IR film covered greenhouse to maintain the same air temperature at the plant canopy. When the effect of the heating system was eliminated, a savings of 13% was directly attributable to the IR barrier feature alone (Simpkins, et al, 1984).

[gistmarrs]

Thin film is made with varying degrees of IR reradiation capabilities or"thermal values". But, we aren't talking about thin film are we?

[KarenRei]

The same physics applies.

Anyways, I think we can agree on one thing here: that blocking near-IR would be good, while blocking long wave IR would be bad. Right?

[gistmarrs]

Exactly right!

[garygid]

And one wants the "blocking" to be done by reflecting,
not by absorbing the IR coming from the outside.

However, I think that the Aptera is not likely to have
coatings on the outside of the windows, because of the
windshield wipers on the front window, and the "rolling"
up and down on the side windows.

But, the front window might have a coating on one of the inside
surfaces of the "sandwich" that forms the safety glass.

[chucchio@mac.com]

Yes, indeed, have the Climate Control work (when desired)
when plugged in, and also when NOT plugged in, and one is
willing to "spend" some of the battery on cooling because
one is anticipating returning to the vehicle in a "short" time.
I must admit, I love my remote function on my chevy.

Typ1 Options Chosen:
Electric/Hybrid: Electric
Production Slot: 2181

[n_dawg]

The same physics applies.

Anyways, I think we can agree on one thing here: that blocking near-IR would be good, while blocking long wave IR would be bad. Right?


Right. The sun is much hotter than the inside of the Aptera (one would hope), so that is correct. ;)

[n_dawg]

Looking for sources for the composites thread (http://apteraforum.com/showthread.php?t=755), I stumbled across this gem:


With the aid of solar power, the Aptera manages to keep its cool, even in the hottest situations. The unique climate control system is always on, which means no more unbearable start ups. Here is how the Aptera multi-zone comfort control system maximizes passenger comfort while minimizing energy consumption:


Zone 1: Dash and windshield area - Solar heat is removed from the windshield and dash before it reaches the passengers. In a typical vehicle most of the energy used by the air conditioner is wasted in removing solar heat, not cooling passengers.
Zone 2: Passenger area - Air-conditioned or heated air is circulated in the passenger seat area to ensure maximum comfort.
Zone 3: Sear area - Seats are heated or cooled. Passenger comfort has been shown to be dramatically improved by providing heating or cooling directly to the body, at a minimum of energy consumption.



Source: Aptera Journey (http://www.aptera.com/takejourney.html)

[Jonathan Sek]

Why couldn't owners use a windshield suncreen, with the side blocking the sun of Al foil or mylar material? Or, like my Hunter Douglas window shades, a honeycomb construction that has a sun blocking component in addition to a thermal, insulating benefit.

[Jonathan Sek]

Of course, I meant shades only to be used while parked. I remember the old bi-fold cardboard shades having a warning disclaimer not to be used while driving (LOL).

[garygid]

It is more difficult to use (or hang) these kinds of shades
in California, now that there is a law against "attaching"
(suction cups, etc.) anything to the front or side windows.

[n_dawg]

It is more difficult to use (or hang) these kinds of shades
in California, now that there is a law against "attaching"
(suction cups, etc.) anything to the front or side windows.

I believe this only applies to when the vehicle is in motion.

26708. (a) (1) No person shall drive any motor vehicle with any
object or material placed, displayed, installed, affixed, or applied
upon the windshield or side or rear windows.
(2) No person shall drive any motor vehicle with any object or
material placed, displayed, installed, affixed, or applied in or upon
the vehicle which obstructs or reduces the driver's clear view
through the windshield or side windows.

Also, even while in motion, "transparent material may be
installed, affixed, or applied to the topmost portion of the
windshield if the following conditions apply:…"

Read the entire section here (http://www.leginfo.ca.gov/cgi-bin/waisgate?WAISdocID=92897724108+0+0+0&WAISaction=retrieve).

[garygid]

Sorry, I did mean while in motion but forgot to specify.

I suppose that if one mounted a 50% reflecting "film" or screen, that
did not "obscure" a "clear view" then it would be OK while moving.

While parked, one can put up a lot of reflectors,
and they do make a big difference.

[chasmccl]

Gary

My assumption is that the ambient unit has the ability to adjust the aptera's internal temp to the outiside temp. This means - Oh well, you know what this means - Now, in Fresburg, the outside temp might very well be 115 F, in the sun. Wouldn't it be slick if there were a plug-in, timed capability, which would reduce the internal temperature of the car to 80 degrees when you got off work? this is quite feasible and would almost guarantee that Aptera would be the biggest seller from B'field to Sac'to, at least between May & October. Your comments are really stimulating!

Thanks

Charlie

[garygid]

I hope that the "Climate Control Timer" feature can be implemented
with just an update in the software, that does not have to be ready
for initial production roll-out. So, ...

1. I will do my best to get Aptera to make the software easy to update
at home (not requiring a "dealer" visit), perhaps with a USB "flash drive".
But, they might have different plans.

2. I will also try to get the hardware configuration (that is much harder
to change after the vehicle is manufactured) to be as flexible as possible
(with fewer hard-wired constraints), so that such future "Upgrades" can
include some very nice features.

I hope for nifty Future Features in:
1. Lighting Options
2. Charging Options
3. Climate Control Options
4. Instrumentation Options
5. User Individualization Options
6. RFID handling Options
7. Valet Mode Options
8. Guest-Drive Mode Options
9. Warning Options
10. Horn Options

But, first,they have to get it out the door!

[ApteraStorm]

Jonathan's post reminded me of a unique vehicle windshield configuration I saw a couple of weeks ago... only as it passed did it dawn on me that I'd never seen it before. The entire windshield was white, except for a few horizontal bands, and only through those bands could you see the driver (and I'd imagine, only through those bands, could the driver see out).. I can't imagine it was legal. I don't even remember where exactly we were... I think it was down in South Sacramento somewhere...

[mjtimber]

With all this discussion of setting up the climate control, I seem to be missing something. In the YouTube tour, the climate control is clearly manual. Is this only for the prototype? It would make more sense to have the climate control computerized, but I haven't heard that this will be the case. Thanks.

[garygid]

If it is not computer controlled, or at have a control that is aware
of the outside and inside temperatures, an always-on system can
end up cooling or heating when you want it to either do nothing
or do the opposite.

In the pictures of the controls, was there a control for "recirculation"
vs. "fresh air" mode of operation?

Example: Get out of a nicely cooled cabin on a hot day, turn "everything"
off, and go into a shop for a little while. Will the always-on system
bring outside hot air into the cabin, heating the cabin when you do not
want it to heat? Or, will it wait until the inside cabin temperature
is greater than the outside temperature before turning on?

Or, will leaving the Climate Control "ON" be necessary, even when
parked in the shade (so there is not much solar assist)?

Many unanswered questions here.
It will be nice to find out just what they are planning to deliver.

I hope for computer control.

[mjtimber]

My hope (and guess) is that they are working to simplify all the controls. It would be great to have the computer be "one stop shopping" for controlling almost all the functions, if it's reliable enough for that. I just wasn't sure if this forum was aware of news that I missed. It seems the solar panel might only run a fan, as the information released to date has been relatively vague on how it works (circulation fan? A/C?). If it is just a circulation fan, which I suspect, that would not require computer control and would be in line with the low power numbers (5-10 watts?).

[KarenRei]

The EV1 had something interesting, which was an AC that you could schedule on a timer, even while the vehicle was charging. The idea was that you could tell AC or heat to come fifteen minutes before you need to leave, and it'll run using power from the outlet, not the batteries during that time.

Not as important with the fresh air circulation, but it'd still be a neat feature. I wonder if patents would pose a problem.

[2258]

All this cold weather in California has me wondering about how much energy the heater in the Aptera will consume. Any guesses?

[evmavin]

You can't patent a timer, several EV's use this my Think had two timers for heat, AM & PM.

[KarenRei]

All this cold weather in California has me wondering about how much energy the heater in the Aptera will consume. Any guesses?

If nothing else is running, including the motor? Just about as much energy as you're getting out in heat ;) The real question will be whether the heat pump can draw heat from the motor and/or inverter. Shouldn't be much available from the battery pack.

[evmavin]

The inverter and motor produce so little heat it would not be worth capturing. To get decent heat in cold weather you need as much as 3kw. This is why in Europe many EV's had Kerosene heaters. The Aptera will require less but it will still be considerable.

[KarenRei]

Assuming an average 85% efficiency and 5kW drivetrain power consumption in operation, that's 750W of waste heat, about half the output of a large plug-in space heater. Doesn't sound insignificant to me. *shrug*

[evmavin]

I guess we will see if they use that energy, I doubt it. You can modify yours though and let me know how it goes:)

[garygid]

Depends upon where the "external" heat exchanger coils from
the heat-pump get their air flow.

For heating, they will want the warmest air available, usually that
would be the air exiting the cabin, if any!
With "max" heating (cabin air recirculates), the air from cooling
the motor and electronics would be next, and finally outside air
(which might be very cold and thus inefficient for the heat-pump to use).

For cooling, one wants to use the coolest air available.
Again, that might be the air leaving the cabin, if any.
On "max" cooling (when the cabin air recirculates) or when
the cabin is hotter than ambient, the outside air would be used instead.
However the outside air might be very hot, and again very inefficient to use.

[KarenRei]

In an ideal system, energy-wise, the heat pump's heat exchanger would be able to draw air from different locations depending on the situation. Whether that'll be deemed worth it, cost-wise and weight-wise, only Aptera knows :)

[NmGfan]

The inverter and motor produce so little heat it would not be worth capturing. To get decent heat in cold weather you need as much as 3kw. This is why in Europe many EV's had Kerosene heaters. The Aptera will require less but it will still be considerable.

My NmG heater and fan run about 3500W. It has two settings, toasty cockpit in two minutes and off. For AC it has electric full roll-down windows. :happy0005:

[KarenRei]

Lol.

Given that it doesn't have AC, I'm assuming it's not a heat pump, but just a simple resistive heater.

[NmGfan]

It sounds like a ConAir blow dryer switched to the crispy position, so I envision a simple coil and squirrel cage fan in some ducting. :happy0025:

[KarenRei]

Lol... that's about what I figured. ;) So, it basically has a COP of just under 1. With a heat pump, the COP will vary depending on how warm its input air end is -- probably 1 to 5, depending on conditions and how efficient of a heat pump they can manage to cram into an Aptera. ;) The more extreme the conditions you're trying to cool or heat, the lower the efficiency.

[evmavin]

Remember the phrase KISS? When building an EV this applies even more. PS- almost all small EV's use basic heater elements, they are self regulating as the resistance varies based on airflow, they can be used of pack voltage and have a broad operating range.

[KarenRei]

I'm pretty sure that the videos have stated that it uses a heat pump, and besides, to have AC, you need a heat pump, so you might as well install a reversible one.

[n_dawg]

Every source I've seen says Aptera will use a heat pump.