groundhog

The above represents temperature derived from ice cores collected in Russia (Vostok), Greenland and the Antartica (plus oceanic sediment) - discuss

The temperatures are derived from stable isotope studies of the core - remarkably, many thousands of data points show the same broad trends.

Homo sapiens evolved/branched from Homo Erectus some 350k to 400k BP. Of course its well known that Homo Erectus had a great fondness for ICE - hence the HEAGW trend at about 440k BP .

The major manufacturers e.g. those companies that know how to build mass market vehicles and distribute them around the world - best estimates for uptake of EVs is about 50% of total vehicles by around 2050. Plenty of time to wait for good quality EVs with the right infrastructure and where they make sense.

Lorenfb

Maybe take a basic electronics class.

acoste

Constructive critics are welcome. But your comment is just an insult.
Similar to doshc's comment who couldn't even come up with his/her own sentence and copied someone else's below. And the originator of that comment didn't understand the subject as well, couldn't respond with anything better.
"Observe the response or lack thereof when questions that require deeper critical engineering thinking is asked when blanket statements are made."

So not sure what is your last comment about. Battery is an energy storage device, its efficiency can be measured as "total energy delivered to the load" / "total available capacity". If you have a different definition, then that's fine, come up with it.

As for the basic electronics class you have no idea who you are talking to. Most likely you have at least one wireless device in your house or one module in your car that has RF chips designed by me. But no one is perfect, if you find errors, your comments are welcome.

hf1

+1
Less drama, accusations, and ad hominems -- more facts, arguments, and logic about the subjects discussed. Works with every forum discussion.

Lorenfb

If a BEV manufacturer's objective was to maximize the power efficiency of the vehicle's drive train beyond having tweaked the motor, using the fastest semiconductors with
the lowest Vsat in the motor controller, what other element would enhance power efficiency? Based on the internal resistance of the battery, significant power losses occur
there. If the manufacture designed and manufactured the BEV battery, tweaking the battery chemistry could result in a lower internal resistance, thereby increasing
the overall drive train efficiency. Using the example in the quotes above, reducing the internal battery resistance by 30% would reduce the power loss from the battery by
300 watts at the 100 amp motor load. Also, less heating of the battery would occur during charging, reducing the amount of cooling needed during charging, further increasing
the BEV's overall efficiency.

So is it possible that Tesla with the new 2170 battery has improved its efficiency over the 18650 with a chemistry change?

doshc

This is what he says: ""well why don't I automate all that max well again it's kind of a distrust I have automated things in the past and I either get halfway through the battery test or all the way through the battery test and I notice some anomalies in the graph and the data and when I go back and check there's always something in the Arduino code or the measurement using an ADC or the connections or something that I botched up".

He is far, far out of the loop on battery testing and equipment used by current production battery engineers. Not to mention the 'Arduino code'. He is decently knowledgable as far as someone who makes Youtube video goes but probably hasn't been employed in current industry for a decade or more.


No. This is elementary electronics and this isn't how the math works. Doubling the charge voltage means you either double the input voltage the battery pack can take (thus also dropping the rated amp-hour of the pack by half) or voltage down somewhere before it hits the battery.

Porsche is touting 350kw - twice or more what Tesla may deploy in in the future and amost 3x current Tesla SC. Taycan would need to have double or more the battery capacity to have an equivalent Tesla charge C rate. It doesn't matter what the charge voltage is, it doesn't change the C charge rate of the pack. What doubling the voltage does is limit I^2 losses and heat through the wire and connectors.

david

+997!

Just when one would begin to think that less isn't actually more, @hf1 proves that in fact, less is more, especially with words (& Porsches!). Nicely done...

PS very interesting thread, discussion & conversation, so (mostly) carry on & let the running data be massaged to prove all of this discussion (& some mental masturbation) one way or the other...or perhaps a way that has yet to be unearthed or identified...

doshc

Yes exactly. Battery efficiency is not some naive formula that @acoste wrote and it operates on multiple dimensions. IR AND how it changes over time AND how it changes through various levels of fast charging is extremely dependent on minor chemistry tweaks even within the same chemistry family. How the IR curve starts and then changes over time and usage pattern requires lots of careful testing. It's a fact of Lithium battery life for all players and also why Tesla will limit top end supercharging speeds dependent on cell age, user behavior and specific chemistry to the pack. There is much proprietary advantage in both chemistry AND battery management here for the experienced.

Lorenfb

Interesting Nissan Leaf Li-ion battery resistance data over time and temperature:

11/20 -13,700 miles, 76 mohms per LeafDD, 20 Deg, 73% SOC
11/27 -13,800 miles, 67 mohms per LeafDD, 25 deg, 63% SOC
11/30 - 13,900 miles, 56 mohms per LeafDD, 27 deg, 71% SOC
12/2 - 14.100 miles, 55 mohms per LeafDD, 28 deg, 67% SOC
12/16 - 14,500 miles, 89 mohms per LeafDD, 15 deg, 93% SOC
12/27/14 - 14,800 miles, 103 mohms per LeafDD, 11 deg, 24% SOC
3/10 - 17,400 miles, 60 mohms per LeafDD, 30 deg, 73% SOC
3/14 - 17, 550 miles, 56 mohms per LeafDD, 32 deg, 47% SOC
4/14 - 19,100 miles, 59 mohms per LeafDD, 25 deg. 38% SOC
5/4 - 19,989 miles, 64 mohms per LeafDD, 24 deg. 48% SOC
5/15 - 20,400 miles, 73 mohms per LeafDD, 20 deg. 41% SOC
5/22 - 20,700 miles, 58 mohms per LeafDD, 28 deg. 50% SOC
12/10/15 - 28,000 miles, 90 mohms per LeafDD, 19 deg. 92% SOC
4/5 - 32,000 miles, 74 mohms per LeafDD, 24 deg, 55% SOC
5/16 - 33,700 miles, 89 mohms per LeafDD, 22 deg, 47% SOC
5/16 - 33.700 miles, 58 mohms per LeafDD, 31 deg, 76% SOC
10/5 - 39,300 miles, 100 mohms per LeafDD, 22 deg, 50% SOC
10/6 - 39,400 miles, 61 mohms per LeafDD, 30 deg, 51% SOC
10/7 - 39,500 miles, 80 mohms per LeafDD, 25 deg, 56% SOC
10/15 - 40,000 miles, 71 mohms per LeafDD, 27 deg, 45% SOC
10/30 - 41,000 miles, 74 mohms per LeafDD, 23 deg, 66% SOC
12/26/16 - 43,000 miles, 110 mohms per LeafDD, 13 deg, 77% SOC
6/10/17 - 49,600 miles, 89 mohms per LeafDD, 19 deg, 70% SOC
7/1/17 - 51,000 miles, 62 mohms per LeafDD, 33 deg, 44% SOC
8/15/17 - 53,400 miles, 61 mohms per LeafDD, 35 deg, 57% SOC
4/2/18 - 62,100 miles, 110 mohms per LeafDD, 18 deg, 94% SOC
6/13/18 - 65,000 miles, 84 mohms per LeafDD, 26 deg, 52% SOC
8/13/18 - 67,000 miles, 80 mohms per LeafDD, 26 deg, 91% SOC
9/14/18 - 68,000 miles, 84 mohms per LeafDD, 27 deg, 57% SOC
10/30/18 - 70,000 miles, 93 mohms per LeafDD, 22 deg, 84% SOC
11/9/18 - 70,000 miles, 104 mohms per LeafDD, 22 deg, 89% SOC
11/30/18 - 70,400 miles, 88 mohms per LeafDD, 23 deg, 88% SOC
12/6/18 - 70,800 miles, 116 mohms per LeadDD, 13 deg, 33% SOC
1/30/18 - 72,300 miles, 86 mohms, per LeadDD, 23 deg, 45% SOC

The method used:
R (battery resistance) = (V(no-load) - V(max-load)) / I(max-load),
The app used is available for iOS & Android for the Leaf. A similar app is available for a Tesla called TM-Spy to determine battery resistance. It would be
interesting for those with a M3 to use that app to determine the internal resistance of the 2170 battery. The 18650 has a resistance of about 100 milli-ohms
at about 70F. As seen from the posted data, battery resistance is greatly affected by temp and to a lesser degree by age. The way the data are generated
is by basically "launching" the vehicle for a short distance taking about 5 seconds with the app in the measurement mode.

acoste

Fair points here, I made a mistake with my calculations.

Lorenfb

TM-Spy app shows an 'Insane" mode MS run at full power for about 4 seconds of around 375 kW at 1,300 Amps.
Note how the pack voltage sags around 100 volts under that load.

acoste

OTA updates...
literally:
Why Haven't Over-The-Air Updates Taken Over The Auto Industry?

daveo4porsche

old industry not adapting to the reality of the world - I would expect this from Acosta who seems to be more part of the problem than part of the solution - Tesla is pushing boundaries and the old guard doesn't like it.

acoste

I don't like it for safety reasons which I have already mentioned. Call me old, I don't care. But I think you appreciate this conservatism when we use it in our design. I have the impression that people don't have automotive experience at Tesla. This is not a cellphone app. For hardware developers there is a long list of action items we have to go through during the design process and there are strict documentation requirements as well. With this system in place there is no way Tesla's software would have had so many bugs and the car couldn't have been released with the braking problem. If they were rigorously validating their updates, I would be less critical as well.

Here in the US any junk car with failing brakes can get a license plate. In many Eu countries one can't even just put lowering springs on the car, everything has to be certified. Not impossible, but needs paperwork. That is a bit on the other extreme, but I do agree with some of it. Over there most safety functions are checked annually on older cars. It totally makes sense to me.

acoste

Found an article that explains the battery types well.

A little info prior.
Tesla uses NCA batteries. It has "Good capacity and power, but lower cycle life and issues with high temperature…’" This is what I mentioned, low thermal runaway temp.
Most other car makers picked the safer NMC batteries. NMC has more cobalt, which is the "ugly guy" (harmful and expensive) but it helps in chemical and structural stability.
I believe the reason Tesla picked the NCA is because they wanted to prove EVs are profitable so they needed the cheapest material with high energy density. Since cobalt is expensive and NCA has the least of it, plus is has the highest capacity (high nickel content), this seemed like the good choice and they didn't care about its safety.
I have to add, NMC 622 or NMC 535 is not a whole lot safer, but they are somewhat. You can see it on the graph in the article. I don't really hear about BEVs burning down other than Teslas. I know about one Jag and one Leaf. Some hybrid i3 burned down due to the fuel system issues, not the battery side. Unfortunately I don't know which NMC they are using. I have to add most other EVs rarely hit trees at high speeds.
The article below says NMC 811 is just as unsafe as NCA. Hope they solve this issue before releasing any product.

Lithium Cobalt Oxide (LCO or LiCoO) is used in the Tesla Roadster. This is why you hear Elon Musk saying that they reduced the cobalt content of the battery by 59% in the last 6 years. But this is not the result of a research. They just switched from the LiCoO to Panasonic's NCA.

What do we know about next-generation NMC 811 cathode?