MemberOctober 2, 2021 at 1:53 am
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?
MemberOctober 2, 2021 at 3:13 am
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.
MemberOctober 2, 2021 at 8:21 am
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.
MemberOctober 2, 2021 at 8:15 am
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.
MemberOctober 2, 2021 at 8:31 am
Actually, clouds of steam (with appropriate lighting) could look pretty sensational! 😃
MemberOctober 2, 2021 at 8:41 am
Yes, I thought so too but was afraid to post it. In the software business we would call such a thing a “Feature”
MemberOctober 2, 2021 at 8:43 am
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.
MemberOctober 2, 2021 at 9:05 am
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.😉
MemberOctober 3, 2021 at 6:59 am
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.
MemberOctober 3, 2021 at 12:45 pm
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
MemberOctober 2, 2021 at 3:49 pm
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.
MemberOctober 3, 2021 at 1:28 pm
Also not an employee, but makes sense from an engineering perspective. We will have to wait and see.