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enjoyoutdoors t1_j2310j0 wrote

More often than not, they DO have a lot of smaller batteries that can be swapped out based on need.

It's just that, eh, the batteries are a safety hazard for rescue services when the cars are in accidents, and to make them less of a hazard they are combined into a large container that is comparably good at confining the hazard.

There are other reasons to, such as thermal control of the batteries and weight distribution concerns.

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PoLoMoTo t1_j24qijl wrote

To add on to this, yes some cells will die before others but in general when the battery pack is nearing the end of its life none of the cells are going to be very good anymore and you'd probably end up replacing all of them anyway. Additionally combining brand new cells with old worn cells is probably not a great idea for balancing.

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sold_snek t1_j24xoq9 wrote

I remember seeing a case where Tesla was charging wild money to replace a battery and the dude paid another company to look it over. While still expensive, it was a lot cheaper for the guy to go battery by battery and find the bad batch then replace it and car was good again.

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PoLoMoTo t1_j24z9ee wrote

I have no doubt that would work but I would be curious as to the longevity of that. Also if it was a high mileage battery or some fluke internal failure, and what percentage of the cells they actually replaced. I'll have to try to find the story sometime.

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greatvaluemeeseeks t1_j25e83m wrote

A few companies do this with Prius batteries and sell them as refurbished batteries. The cells aren't too hard to disassemble and a dead cell is pretty easy to isolate. A refurbished battery is much cheaper than a brand new one from Toyota, but the batteries don't last very long before another cell eventually dies since they probably have 150k+ miles on them and Toyota, in my opinion, provided inadequate cooling for them and should have told consumers the battery's cooling system required regular maintenance.

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Lyrle t1_j26gnwi wrote

Rich Rebuilds had an episode like this. The car featured there was not very old.

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ikingrpg t1_j261dqp wrote

Yeah, that was a rare case where the car wasn't that old, but one cell just went bad. You wouldn't want to do the same thing if all the cells were old.

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Bensemus t1_j2co8yg wrote

This is just the difference between dealership repairs and independent garage repairs. Tesla isn’t interested in diving super deep and doing a one off fix. They do high level repairs which cost more.

It also shows that Teslas aren’t locked to Tesla like so many claim. You can bring it to other people to get it fixed.

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sold_snek t1_j2csqgs wrote

> You can bring it to other people to get it fixed.

You need literal electrical engineers to do it and Tesla won't touch your vehicle afterward. It's a pretty big cost to do anything outside of Tesla.

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rickymilby t1_j25y914 wrote

This is correct, you can't mix new batteries and old batteries as it is impossible to balance.

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WiryCatchphrase t1_j24v28y wrote

There's some confusion here. Batteries by definition is a collective noun and are comprised of cells. EVs are comprised of many cells controlled by computer processors to manage usage heat and life cycle. Generally you don't want a cell to get about 80% or. Below 30% capacity, nor do you want to wear out a handful of cells charging and recharging constantly becuase they're closer to the inlet/outlet.

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ShwAlex t1_j26rjhj wrote

Microvast has fire proof batteries now!

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BazilBup t1_j25911t wrote

Also Tesla have built int rhe battery into the core chassi so they save on weight. And yes you can upgrade individual cells which can be done on old bicycle batteries.

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Commercial-Army2431 t1_j23439h wrote

Maybe loss of efficiency with added resistance between multiple batteries and systems? Idk???

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DoomGoober t1_j23sdmh wrote

As I understand it, car batteries are arranged in packs of serial or parallel configurations to intentionally harness the resistance of serial or parallel to achieve desired voltage.

Thus using multiple batteries (and the resistance introduced by serialization or parallelization) gives the designer some control over the voltage.

Whether this is a side effect of needing multiple batteries for other reasons or a specific desired feature, I don't know, but it reduces the need for resistors.

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VrebPasser t1_j24m8z3 wrote

Not quite true as you put it, but the general principle applies. It's about voltage stacking and the same current being drawn from multiple sources.

Think of it as a slide going from the top of a building to the road below. You have a number of people that want to slide down (that would be the load). If you have one huge slide, the people will be hurting each other as they descend. Therefore, you add more paralel slides (batteries) so they can redistribute themselves and be less cramped (less overloaded system). By adding more batteries in series, you make the slope more steep so the people get down faster (more force to "push" them).

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Commercial-Army2431 t1_j242rbp wrote

Weird I’m being downvoted. I thought I was asking a legit question. Oof

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OhNoItsThatOne t1_j243z7d wrote

That was not a question, it was a speculation. And too many question marks. (I didn't downvote)

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corsicanguppy t1_j247xg8 wrote

And the last question was asking us whether he didn't know. That's something we can't really answer without telepathy.

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veloace t1_j244l94 wrote

It's the question marks.

Usually people use multiple question marks like that when they aren't asking a real question but asking a rhetorical question to make the OP sound like an idiot. Usually in the context of trying to point out "obvious" information.

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Commercial-Army2431 t1_j2451f6 wrote

I can see how that would read like a snarky belittling response. It was not my intention.

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veloace t1_j24ex8t wrote

I know it wasn't your intention, just trying to give you some insight on the downvotes. People here will read punctuation before they read the words.

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