EVs Are Great Around Town, But.......

[oil pan 4]

Like a nuclear submarine, not everything reacts well to [being shot].
(Red october)

[Isaac Zackary]

Originally Posted by Snax

YThis has me wondering about the long term practicality of that strategy however. I.e., as whole pack capacity declines, when one module goes bad, are the rest likely soon to follow?

In comparing to ICE cars I see a few things to take into consideration.

1. Longevity of ICEV components compared to longevity of EV components. If we're getting +200,000 miles out of our ICEV's, that would be nice to do with EV's. But of course in the beginning people didn't get 200,000 miles out of their Model T's and VW Beetles. After 50,000 miles you just rebuilt or replaced the engine and/or transmission. But with newer models that number grew to every 100,000 miles. Then every 150,000 miles. Now some are going past every 200,000 miles. Maybe something similar will happen with EV's and their batteries. But it's hard to "downgrade" to a car needing major repairs every 50,000 miles or so, unless #2 isn't so bad:
2. Cost and ease to repair. Rebuilding a gasoline engine used to be pretty cheap if you knew where or how to do it. My dad would rebuild engines all the time, namely Chevy V8's, and for pretty cheap too. My sister and I both got into the some engine rebuilding too on our own cars. It used to be a lot cheaper to do that than to buy another car. But newer cars seem harder to work on, and sadly it seems that EV batteries are designed not to be worked at all and are expensive to replace. I mean, who cares if you have to replace it every 50,000 miles if it only costs $1,000 to do so. But at prices of $8,000 and up, I don't think that's going to go over very well.
3. WarrantiesSo the other thing to do would be to just make car manufactures put long warranties on their batteries. But this may or may not be enough. With longer warranties, it looks like companies like Nissan just change the batteries more times instead of making batteries that last longer. So once the car reaches it's 8, 10 or 12 years of warranty, whoever's the owner at that point has to deal with the battery degradation and resulting depreciation. This could knock EV's off the list from ever being the old beaters that high school and college kids and stingy people (like me) look for.

[RedDevil]

Tesla batteries seem to hold up well... they stabilize after losing 5% of their range without degrading much further.
https://electrek.co/2016/11/01/tesla...y-degradation/
Seems they should easily outlast an ICE engine on average.

So much for modularity. Maybe it is better to focus on reusing the battery once the rest of the car is done for?

[Isaac Zackary]

Originally Posted by RedDevil

Maybe it is better to focus on reusing the battery once the rest of the car is done for?

For most cars, yes. So for the mass population you have a very, very valid point.

But then you have those that of us that have gotten over 700,000 miles out of the car. If taken car of, some people have gotten over 3 million miles. You also have those antique collectors that in 30 years will want an antique Tesla. For those the question will be "what does a Tesla Battery cost to rebuild or replace?" I guess the good thing is that if it's too expensive (car is disposable) then that will keep everyone up on the latest in safety technology because driving a decades old car won't be an option.

[Snax]

Well I think the issue of degradation is one of bulk statistic data. I.e., degradation is measured at pack or module level, not individual cells. And due to variances in materials and manufacturing, some cells just aren't as up to the task as others, but can impose a significant impact on the performance of neighboring cells they are grouped with. There's an entire web forum dedicated to DIY powerwall building, and recovering well used cells with good capacity is a significant part of making it cost effective.

Most packs they recover the good cells from have been hobbled by one or two cells that couldn't hold up.

So in that respect, I think modularity does make sense, but cell production quality also plays a huge factor. Tesla is obviously shooting for using the highest quality cells they can. Other manufacturers may not be as picky, so their results are subject to higher variances.

What I believe we will see developing is not just more compact and lighter weight cells coming to the market, but better consistency and higher reliability for the cells that are produced. I.e., improvements in tech will be a bit of a factor, but quality control of cells will ultimately make or break a break a vehicle platform.

[RedDevil]

I found 2 videos that answer about all we've been discussing about the Tesla batteries... Very instructive!

https://www.youtube.com/watch?v=TdUqQZC2dcE

- Tesla's 21700 type cells are mounted in parallel in 46 cell bricks. Each cells connector doubles as a fuse, so if it shorts it will blow that while the other 45 cells keep the pack alive at only slightly reduced capacity.
- Tesla battery packs seldom fail, and if they do they are almost always 2013 batteries or older, and fail earlier in their life rather than late. None of the failed packs was out of warranty.
- The battery heating and cooling system is very advanced, making effective use of residual heat of every heated or cooled system in the car.
It is managed by the 'super bottle' tank/pump system...

Part 1 is interesting too; it covers chemistry, abundance of elements etc.

https://www.youtube.com/watch?v=kGFiaWvD-KI

Then if you really have time to spare:
http://evtv.me/2018/05/tesla-model-3-gone-batt****/

Drop-off-the-chair stuff. The 4 battery modules weigh less than 800 pounds all together...! That's surprisingly light for a car with that range?

[Isaac Zackary]

Yes. Tesla is really ahead of the game. And I hope their batteries last and last.

But even then, the next question is when are the prices going to come down. Sure, the $35,000 Tesla is coming. But without tax incentives, that's very expensive for most of us. Sure, we need to factor in what would be saved by using electricity and not having oil changes and such. But there have been times that you could get a Mitsubishi Mirage for under $10,000 brand new from the dealer! It would be nice to see $20,000 and $15,000 EV's. Perhaps even $10,000 or even $5,000 long range Tesla motorcycles.

[Frank Lee]

The Duhmerican motorist laps up $60,000 SUVs and PUs like they are going out of style (sadly they aren't).

[oil pan 4]

Tesla batteries could last longer than the company.