Skin cooling system info

[Joseph Cook]

If I wanted to customize the look of my Aptera with a vinyl wrap, of course avoiding the solar panels ????, would that impact the vehicles skin cooling system?

[Raj Giandeep]

I was under the impression that all the colors are wrapped. Custom or white, silver, black.

[Joseph Cook]

I hope not as, from what I’ve read, average durability of a vinyl wrap is only ~5 years. Well maintained paint should last decades.

[Bob Kirchner]

Paint requires a paint shop in the production facility, which is very expensive and has significant environmental problems, so Aptera is pursuing the path of least resistance, given their limited captal resources.

[GRAUSS Thierry]

What would be nice is having the pigments embedded inside the composite itself.

[Bob Kirchner]

I agree. In any case, if the wrap begins to look shabby (or in my case, really REALLY shabby) you can always either re-wrap it or paint it at that point. At least by that point, rust won’t have set in.

[GREG MIRICH]

The life span for a wrap depends on the quality of the vinyl and how it is taken care of. There are products on the market that prolong the life of wraps

[Bob Kirchner]

Also, I would imagine, on the environment in which it is used. Gravel roads and winter grit will take their toll, probably.

[John Malcom]

All of the colors offered by Aptera will be raps.

[Riley …]

I think the color of the wrap would affect the cooling much more. A black car in the sun is hotter to the touch than a white car.

[OZ (It’s OZ, Just OZ)]

The wraps however are confined to the lower portions of the vehicle for the most part. You will not be able to wrap or change the color of any area with solar. Except for the hood (If not solar optioned.) and small edge areas, the upper area that is mostly exposed to direct sun will either be solar array or glass.

[Riley …]

You can wrap the top of Aptera just need to cut out all the solar cells. I hope Aptera or a third party sell a kit for a full solar car to match any color you want.

[Henry Kitt]

This is actually my primary concern with Aptera, the wrap. Cost cutting on their end costs the consumer more down the line. The base without wrap is actually a gloss finish, so you can get the car without any wrap at all and it should look nice. It seems the reason for the wrap is that possibly the base composite shell might not be scratch resistant. To counter this, you can immediately take your new Aptera to have it clear coated, which would be less expensive at least, than getting a full on paint job, and less expensive down the line.

From Aptera: “The base of our Alpha vehicles has been black to start. However, we anticipate that the colors of the production versions of Noir, Luna and Sol will be Black, Silver, and White at their base, without a wrap.”

These pictures are what the Noir looks like without a wrap. It is admittedly cool to have the color contrast of matte black and gloss black though, a look that would be sacrificed if buying it unwrapped. Though the cost of having a professional remove a wrap and put on a new one will likely run you $2,500+ in this inflated economy. Clear coat should cost less in the long run but more up front unless there is a discount for buying the Aptera unwrapped.

[Gabriel Kemeny]

Yeah, that idea of a discounted unwrapped vehicle has merit.

[John Malcom]

If you choose custom color you may be able to negotiate what you want. I am satisfied with a wrap applied by Aptera during normal production. The efficiency features of the Aptera far out way any concern I would have about the finish. (Function over form)

[Llewellyn Evans]

Are radiative cooling films to be used on the solar panels for the purpose of getting more power from the panels? Radi-cool or similar? They are cheap, light weight and increase solar panel efficiency.

It may also be possible to use them for radiating heat from the smooth body of the car as a plastic wrap.

[Michael Trieu]

It probably wouldn’t be a great idea to place a radiative cooling film on top of a solar panel because it would block all the spectral frequencies that the solar panels use to convert sunlight to electricity. Your best bet is to wrap all the other areas not covered by solar panels with the radiative cooling film and low-E glass for all the window surfaces. That should cut down on the AC load. What’s great is that some radiative cooling films (especially ones based on BaSO4) can achieve sub-ambient temperatures, even in full daylight, and can be colored practically any hue or shade and still be tuned to reject the rest of the UV and visible light while still allowing LWIR to pass through. Maybe Aptera should get in touch with SkyCool Systems. I hear they’re willing to discuss automotive applications, although their main marketing focus seems to be building HVAC augmentation.

Edit: Actually, I was mistaken. The same guy who founded SkyCool Systems also figured out a way to reject heat from solar cells without interfering with their power-generating capacity!

https://www.researchgate.net/publication/281911166_Radiative_cooling_for_solar_cells

• This reply was modified 5 months, 2 weeks ago by  Michael Trieu. Reason: Added information about radiative cooling for solar cells

[Llewellyn Evans]

It is a 3M product designed specifically for putting on solar panels.

[Michael Trieu]

It is being manufactured by 3M, but it’s also a partnership with SkyCool Systems as part of an ARPA-E grant for a joint research project that ends this November. And it’s not entirely clear that the “solar panels” are going to be PV. They appear to be targeting the solar thermal market specifically.

http://www.arpa-e.energy.gov/technologies/projects/passive-radiative-cooling-film

[kerbe2705]

Remember that the alpha prototypes are made of fiberglass – the production vehicles will be made of other composites that may or may not share common color from panel to panel. Some composites are not paintable and others are molded with color integrated into their surface resin layer.

[kerbe2705]

Founder Steve explained in a recent video that the belly of the Aptera serves as the radiator – cooling channels do not run throughout the body. If you look closely at the belly rendering you’ll see that there’s a panel distinct from the rest of the body – note the connector-holes.

I believe it was CTO Nathan who said that the belly material has not yet been selected – that it might be aluminum.

[OZ (It’s OZ, Just OZ)]

IIRC the belly panel will also end up being the battery support tray. I’m not fully versed in how most EV’s are designed, but is the normal practice to enclose the batteries in a combustion resistant chamber? (If so I would imagine Aptera will follow suit.)

[Joseph Cook]

And also to resist impingement.

[Len Nowak]

In a video with Nathan, he said the composite, at least, is not combustible because inflammable ingredients are used in the composite recipe

[OZ (It’s OZ, Just OZ)]

@Leonard Nowak not combustible is good, but as Joseph mentions resisting impingement is probably more important, the composite can still melt.

[Len Nowak]

I must have missed that comment about an aluminum belly considering that area is used for cooling, dent resistant body and the fact that the strength comes from the composite four piece composite capsule. In there lean manufacture I thought avoiding tooling for pressing a metal belly made sense???

Crash testing ahead too… to also validate assembled decisions!

But Aluminum is used in some framework I was told

We shall see ¯\_(ツ)_/¯

Lots of “reality” fitting together in development!

[Richard Palmisano]

Doing a little digging, I found some data that suggests that laminar flow, which is amazing for aerodynamics, is not great for heat dissipation. When laminar flow is achieved, a boundary layer is created and that boundary layer is insulative.

This means that using the exterior panels as radiators might not be the most efficient means of dissipating or gaining heat. This is a huge deal for southern climates with high humidity.

Can we get a little more information related to the climate system?

[Peter Jorgensen]

https://www.google.com/search?q=skin+cooling+aircraft&rlz=1C1GCEB_enUS891US891&oq=skin+cooling+aircraft&aqs=chrome..69i57j0i22i30.2808j0j7&sourceid=chrome&ie=UTF-8

https://arc.aiaa.org/doi/abs/10.2514/2.6472?journalCode=jtht

https://www.osti.gov/biblio/423103-aircraft-skin-cooling-system-thermal-management-onboard-high-power-electronic-equipment

[Richard Palmisano]

Peter, at 30,000 feet the skin of the aircraft is subjected to -48 deg F (avg), I think that’s fantastic for aviation and you can reject as much heat as you literally want.

At sea level, with 80-90% humidity and 95 deg F surface temps, I am more curious how effective this will be.

[kerbe2705]

In your last line did you mean “cooling” or “climate”? I understand “climate” in reference to HVAC, not motor, battery and power electronics cooling…

[John Malcom]

I think the Aptera engineers are pretty astute at doing research and experimentation to determine the best solution for engineering the Aptera for a range of environmental conditions. They have a mix of engineering skills including automotive and aerospace and collaborate in a multidisciplinary fashion. Of course, the proof of any engineering solution is in operational testing. I believe they will do thorough testing and remediation if necessary so that my Aptera will function well in the Florida heat an humidity.

[Richard Palmisano]

Climate, cooling, etc.

If you look at other EVs, there is a multi-junction valve (Tesla octovalve for instance) that diverts cooling and heating respectively to batteries and climate system.

John, I’m not saying that they do not have a plan, have engineered a solution, but it’s a new technology in regards to being applied to the automotive space. As someone who want’s to be an initial adopter, with a low allocation number, I have questions about the systems of the vehicle.

This isn’t confrontational, it’s not saying the engineers are dolts, it’s not saying it won’t work.

I have seen most of the information presented and understand the approach using the skin as a radiator, but I have also researched the viability of laminar flow in relation to heat/cooling transfer and what’s good for aero is not necessarily good for heat/cooling transfer.

[Richard Palmisano]

John, I have no doubt that the engineers have researched this and have a solution. Can we get some information related to this though?

I am not saying it won’t work, I’m not saying they haven’t worked it out, nor am I saying they are dolts. I am saying laminar flow is not ideal for heat gain/dissipation. Turbulent flow is better at this.

I as an early adopter with a low reservation number have questions. I have watched all of the provided information from Aptera, and I like their presentations. It’s getting close to ‘nut’ time though. Rather than a ‘hey they got this’ response, is there someone with actual information related to the systems and how they will perform?

[John Malcom]

Richard, I did not take it as confrontational. Sounds like you might be a heat transfer person with legitimate concerns as you will get an early production model. There is a body makers segment coming up. Perhaps we can get some discussion on the cooling topic included. There was none in the makers presentation on batteries

[Joshua Rosen]

It would be a fascinating topic for a webinar. However that will have to wait until they’ve filed all of their patents and starting shipping the car. This is core IP for Aptera, they have to be careful to protect it.

[Richard Palmisano]

I agree. I do understand that this is IP territory, but it is a huge concern for my location in NE Florida. AC is king here…????

[Roshiyu]

Imagine, if this entire time, they ran simulations with it set to a default cruising altitude for airliners. How big of a D’OH moment would that be? XD

[Richard Palmisano]

LOL…I am not saying that this is the case at all!

[John Malcom]

A big OOOPS for sure with a lot of hand waving……..

[John Malcom]

Joshua, I am not sure you are in a position to make such a statement as there is no information available To us on what Aptera considers protectable IP and what if anything they would want to submit a patent for. It may not be patentable as “Knowledge of it (The concept) has been known to the public” one of the disqualifying factors for a patent. Or they may have applied already which would not make sense as they are in the early stages of prototype development.

At any rate it does not hurt to make an inquiry. This is for an early adopter with some knowledge of heat transfer mechanics with a legitimate concern.

If they have a reason Not to answer fine

[Joshua Rosen]

John

I’ve spent my career on the forefronts of technology, in my case high performance computing, and I have a number of patents. Most patents aren’t fundamental, companies get them to fill out their patent portfolios, and a very few are and those are the important ones. Cooling is outside of my area of expertise so I don’t know what’s patentable in this field and what’s not but as someone who’s been through the process Aptera’s skin cooling sure feels like it could be a fundamental invention. I have no doubt that they’ve already filed patents in this area but there may be follow on patents that haven’t been filed. In patent law you lose the right to patent something if it’s been publicly disclosed. You can show it to an outsider under an NDA, that’s not considered public, but if you make any public disclosures it goes into the public domain. That’s what I was getting at by saying that they have to have all of their IP ducks in a row before they can do a webinar. I also mentioned not doing it before they’ve shipped the vehicle. This is a practical consideration not a legal one. As soon as the car is available the Chinese are going to reverse engineer it. I’ve done business in China and it has not been a happy experience, I’ve also experienced attacks from China on my source control server. The patents will protect them in the West where patent laws are strong but in China, where IP rights are not respected, the best strategy is to keep information private until it’s no longer possible, i.e. until the product is available.

My undergraduate degree was in physics so I’d find a detailed explanation of their cooling technique fascinating and I look forward to a webinar on the subject. However I wouldn’t expect it until they’ve filed all of the patents that that they are going to file.

[John Malcom]

I am not sure why this post was directed at me, or what this has to do with answering Richards question. I am also not sure what our credential posturing achieves on the forum. But, here is mine.

My first two degrees were in physics and I did my post doc work at the IBM Thomas J. Watson Research Lab in Yorktown Heights and Cambridge MA, probably close to where you live. As you may know, researchers at the IBM Labs are not allowed to hold patents, IBM is the filer and owner. I left IBM as a Senior Vice President of R&D at the time when the Federal Systems Division was sold to Lockheed Martin and went on to be a Senior Vice President of Technology at Citi Bank. I lived and worked in China for seven years so am very familiar with their enterprise culture and in fact admire their model and wish we could match it. My wife is PRC and currently a professor of math at the University of Florida. She is PRC Chinese to the core and always a reminder of their culture.

I don’t think that Aptera management are neophytes with regard to China business. The original Aptera IP was sold to a Chinese company and Aptera Founders got it back. Also, the CFO has a Chinese background and, based on her credentials, quite an astute business person. I do not believe that China will be able to take unfair advantage of Aptera.

I certainly support your concern about protecting Aptera IP. But I trust Aptera management to balance protection with the transparency they have shown about sharing their technology, allying enthusiasts concerns, and answering questions.

So let’s trust Aptera management to manage their business and make the decisions on how to respond to questions. We have different backgrounds and our experience is not necessarily applicable to their business which in itself (Aside from the vehicle) is innovative and breaking ground.

Feichang ganxie nin

[Joshua Rosen]

John

My original comment on this tread wasn’t directed at you, I was just trying to explain to everyone else why they might not be able to do a webinar at this point. The last comment was a direct response to your statement that I wasn’t in a position to make such a statement. I was just clarifying why I thought that it might not be possible to share this information at this time. Of course it’s up to Aptera’s management to make that decision. I’m sure they have first class IP attorneys and if everything is already squared away I’d be fascinated to hear the details of what they are doing in this area. We seem to have gotten off on the wrong foot with each other, I hope we can get back to a less confrontational relationship.

[Richard Palmisano]

Joshua, your summation related to NDA and patents reminds me of Sandy Munro and his podcast. He has been asked many a question related to Aptera and other companies that he is working with and he quickly will say something to the effect, “ummm, yeah can’t talk about that one…NDA…lets move on”.

[Carl Knapp Knapp]

Your concern about the heat transfer skin effect is valid. I asked them 7 months ago during one open meeting and they responded they have addressed this in their design. I would hope so living in AZ where the temps hit 120F. But at least it is a dry heat.????

[Richard Palmisano]

Carl, dry, moist (love that word) heat, doesn’t matter. The fact also that we will be placing our vehicles in direct sunlight with solar thermal gain to gather miles adds to the question. Typically I search for a shaded spot here in NE Florida now to keep the radiant energy from making the cabin unbearable.

I’m very excited about the vehicle. I see it’s potential for my use case, daily commuter.

I think Joshua has a great idea. They should do a focused presentation on the tech they propose with some ‘potential real life use cases’ to address this question. I know I am not the only one.

[Keith Derbyshire]

What happens to the Aptera in the cold and rain or when driving through puddles etc? Because the underbody is effectively heated, are we going to see Apteras covered in rising clouds of water vapour as the in-body cooling pipes evaporate it. Obviously, when driving along this would stream out behind. Has anyone considered this, because it might not look too good, especially at traffic lights or other stationary moments?

[Riley …]

The cooling system for aptera will never get more than several degrees above ambient so you will not have a situation like that happen. It’s a common misconception that electric cars cooling systems are as extreme as internal combustion cars but the delicate electronics and batteries would fail if Temps were to exceed 120°f.

[John Malcom]

Ambient in the AZ and Mexico may well be around 125F. We have enthusiasts in those areas that are worried about battery cooling as well as others in warm humid climates. Aptera engineering is aware of this concern and will engineer and test accordingly.

[John Malcom]

Let me be clear, this is not a response from Aptera engineering but from someone with related experience

I don’t know about the tech for the Aptera approach to the battery cooling issue. They have an innovative, and I am sure proprietary cooling system. I know we will have more information about the specifics as development and testing moves along.

I have this experience working in EV development. It is generalized so as not to reveal manufacturer proprietary information. I am sure it may differ from other sources of this information, but will be in the range +/- some.

EV battery cooling systems are used for three primary things. Of course to make sure the batteries operate in the best range for performance and longevity, and to make sure temperature is evenly distributed across cells.

Temp range for the batteries should be kept between 60 – 95F and the temperature differential between cells between 37 – 39F.

Of course, the type of cell chemistry and geometry of the cells is a factor in battery temperature maintenance as well as the battery control electronics. I trust Aptera to do excellent engineering on batteries and the cooling systems as they have safety as a first principle and will do exhaustive testing to insure optimum operation and safety.

[kerbe2705]

Actually, clouds of steam (with appropriate lighting) could look pretty sensational! ????

[John Malcom]

Yes, I thought so too but was afraid to post it. In the software business we would call such a thing a “Feature”

[Joshua Rosen]

The problem in EVs is too little heat not too much. An internal combustion engine is only about 30% efficient, the rest is heat. An electric drivetrain is somewhere in the neighborhood of 90% efficient leaving only 10% to be lost as heat. An ICE also operates at 100s of degrees whereas batteries are comfortable in the same temperature range as people. In the winter ICEVs get their heat for free, all they have to do is route some of their waste heat though the heater core rather than the radiator. An EV drivetrain doesn’t generate enough heat to warm the cabin let alone dissipate any heat to the outside. Heating is extremely costly in an EV, I have a 2019 Model 3 which uses resistance heating, it consumes about 100Wh/mile which is equal to the energy required to run an Aptera. Aptera has said that they want to us a heat pump which will cut the heating costs substantially. In an EV the battery has to be heated in the winter, not just the cabin, so retaining heat is critically important. I would expect that very little heat is going to be sent to the skin in winter, the harder problem for Aptera to solve with skin cooling is keeping the batteries cool in Arizona in the summer.

[John Malcom]

Joshua, your statement is only half true. Both high and low battery temps affect battery performance and longevity significantly. Lets not mislead people on the forum. Heat is a very real problem with EV batteries for a number of reasons. Let’s not minimize it. Think for a minute. Why are there so many engineering articles published regarding EV battery cooling technology. Why is so much time spent trying to get battery cooling technology to work efficiently and effectively by Aptera and other EV companies. If heat is not an issue, why have a battery cooling system at all? Read about balancing temps between batter cells in your research to understand the challenges for battery cooling in a hot climate.

If you don’t think high battery high temps are an issue (Safety) review what GM has going on with the Bolt to the tune of $2B and a massive recall. It is not only battery chemistry. As you know, I drive a Model3 as well. In FL the issue is very definitely batter high temps for performance degradation. We have no winter here.????

[Joshua Rosen]

I was just making the point that much less heat has to be dealt with in an EV. The temperatures inside of the combustion chamber of an ICE is in the neighborhood of 260C, the flame temperature is 10X that. Nothing in an EV generates anything like those temperatures unless you have a battery fire. Whereas ICEs normally operate well above the boiling point of water the motors and batteries in an EV can’t and in case of the batteries they have to be held at around room temperature to operate correctly and not to degrade.

The Bolt fires are due to a pair of manufacturing defects in the LG batteries, not GM’s thermal management. Those batteries have been catching fire not only in Bolts but also in Hyundai’s and in at least one case a VW ID.3. I doubt any one of those companies messed up their thermal management but the chances that all three did is vanishingly small. GM knows a thing or two about EVs, they invented the modern EV with the EV1. I had a Volt for three years and it had zero battery degradation in that time, it’s possible that Chevy was able to hide it in the big buffers that they used, but it’s mostly due to the fact that they had very good thermal management. Nissan air cooled their batteries which led to dreadful battery degradation in hot climates but it also proves my point that there isn’t enough heat to boil water. If there was that sort of heat they never would have have attempted to air cool the batteries.

[John Malcom]

Joshua, I believe you are getting your Bolt battery information on the internet or from the general media. I had a consulting engagement with GM working on the warranty system and connection with engineering. I can assure you that there are a number of factors causing the fires in Bolt batteries to include the cooling system. You “Can’t always believe everything you read in the papers”. Don’t over simplify these kind of defects or rely on abstracted information from less than technical journalists as these are not single factor issues by any means.

I know you are a high performance computing expert so I am sure you are familiar with the the concept of weighted, complex factors and sub factors, that need to be considered and analyzed to determine the root cause of problems and the development of a systemic solutions for either computing system issues or complex engineering development and production issues. As a practicing Six Sigma MBB in engineering and production processes I have, in nearly 35 years of practice, never found a case where only a single factor caused a significant defect.

WRT to battery heat, I will refer you back to my post on battery operating temperatures. and suggest that you look at engineering design and testing data. My family (Son and daughter, both had Volts) Both had the often advertised failure of all of a sudden losing motive power. One was a software defect fixed by a software update. One was a battery defect fixed by replacing battery cells. They had between 60-70,000 miles on them at the time and were fixed under warranty. Of course they no longer own those vehicles. GM no longer makes or sells the Volt. as I am sure you are aware.

WRD to the Bolt. Most of the Bolt is made in Korea and assembled in the US by GM So GMs EV experience is only secondarily relavent. GM was not the first to develop or try to sell electric cars. Electric cars have been around since the late 1800s. Being the first does not predict you will have the best experience or technology to succeed long term in the market place. A computing example I am sure you are familiar with is Univac which really started the commercial computer business. How many Univac/Unisys computers are in the market today?

You and I often spar on this forum at great length taking up a lot of space. Let’s make a deal. We will to only post once for each topic and not counter post each other so others have a chance to express their opinions and we don’t take up a lot of space on the servers.

WRD to Leaf’s air cooling vs. GM liquid cooling, here is an article that discusses a couple of different points of view and generally not favorable to the Leaf (Air cooling) approach

[Ron Ledohowski]

I suspect some kind of existing adaptation of Hydronic Heating and Cooling (glycol based) through channels or tubes in the composite core. Look it up. The adaptation & application would be an interesting one, IMHO.

I’ve posted my take on this a while ago.

Anyway, It has also been used in higher-end camper trailers (& other applications)… as one example. Cabin ambient (radiant) temperatures would also be controllable as well as a result of this tech. Also be great for melting/keeping snow off the vehicle.

If I’m off on the tech, bet I’m close enough. It’s the idea (or general concept) I’m referring to.

P.S. I don’t work for Aptera so by default, I am speculating & deducting.

[John Malcom]

Also not an employee, but makes sense from an engineering perspective. We will have to wait and see.

[R Daniel Hood]

Phew, long thread. This is my most pressing question about the Aptera as it not only affects battery life and performance but personal comfort as well. It would suffice for me if Aptera would publish some test results.

[G Johns]

Sirs and Madams, I think they should wait until production starts before they openly show tech and solutions.

Remember how a crooked FORD engineer stole delayed wipers from an inventor.

[George Hughes]

I don’t think there are any limits in the size of the ‘radiator’ plumbing which is obviously installed in one or more layers of fabric and composite resins. The design, including size (really, it could be really large … we don’t know) and incorporation into those parts is proprietary. Anyway, the idea of cooling through the skin allows for a very large heat transfer area, mitigating the inefficiencies of the laminar flow. The electronics and battery, both of which are not normally taxed and generate excess heat because the Aptera is twice as efficient as other electric cars. Add the drive motors; a distinct source of significant heat in most EV designs and place them in the wheel where heat is easily mostly dumped distant from the body.

The point is, the amount of heat generated is predictably smaller in the Aptera than conventional wisdom would suggest based on other EV designs.

I can’t imagine the design being adopted without a thorough review of feasibility as they always could have adopted a more conventional solution.

[Joshua Rosen]

The car is supposed to use 100Wh/mile if we assume that it’s 90% efficient then they only have to dissipate 10Wh/mile, that’s not a lot, even if we double that to 20Wh per mile that shouldn’t be a problem.