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CT scans of batteries

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Re: CT scans of batteries

#51

Post by pontifier »

sam1r wrote: post #5

>> Create an account and continue browsing on a computer to experience the demo assets. Super cool, but requires account to check out a scan-which won’t work on mobile regardless, fyi.

The viewer is really worth checking out. The full model seems to be there, though some settings look disabled.

I can imagine making changes to a battery production line, scanning a few samples, and using the scans to tweak angles, speeds, stops etc.

I'm sure these scanners are expensive. Very cool though.

Re: CT scans of batteries

#52

Post by ajnin »

caycep wrote: post #49

How are they getting color? My impression is CT scan is mostly measuring density and x-ray absorption. Are they doing false color based on some sort of data (vs photoshop?)

The article mentions in passing that "The negative electrode is copper; its yellow color in our visualization means it’s denser than the other materials in the battery." So presumably the blue to yellow scale corresponds to material density.

Re: CT scans of batteries

#53

Post by tppiotrowski »

throwayyy479087 wrote: post #24

Those tabs on the final item are what caused the Bolt fires. The manufacturing was incorrect, and they had to replace every cell.

You led me down this rabbit hole [1] Curious choice my GM as I thought the LiPo packs were more prone to distortion/swelling which can cause the membranes break and the battery to short.

[1] https://cleantechnica.com/2018/07/08/tesla-model-3-chevy-bol...

Re: CT scans of batteries

#54

Post by ggm »

anon946 wrote: post #44
vitruvius wrote: post #2

The LG lithium ion cell that's second on this page is the one inside the Tesla Model Y battery pack.

That's interesting and somewhat surprising. I'm not knowledgeable about battery design by any means, but I would have thought that there would be a better way to make a battery pack for a car than connecting thousands of small batteries together.

if I remember my basic chemistry, batteries don't deliver voltages at the level of 10/20/100v directly often, its more commonly 1/2v or 0.5v class voltages. You have to have a much more 'aggressive' chemical reaction to deliver higher voltages. And, the same with current: a single surface between two reacting things delivers less current. Its a function of surface area. Same with capacitance: you sometimes need 'more' surface to big up the effect.

Therefore all you have is stacking it up. parallel or serial, thats what there is to get higher voltages, more current draw, longer life per-cell.

Inside a lead acid battery its multiple surfaces, sub-cells. It's normal. inside almost any domestic battery I suspect its sub-cells, sub-cells all the way down.

A giant roll of surface, to increase the area in contact might be one way of getting "more" in terms of current draw or lifetime. I bet that its voltage remains close to the constant in this, hence Tesla "stacking" up the rolled cells, to boost voltage.

Re: CT scans of batteries

#55

Post by elihu »

caf wrote: post #46
real-dino wrote: post #36

I have some LiFePO4 batteries powering my laptop, and onboard electronics on my boat. They are very heavy, but have a super long life. Often forgotten, they are used a lot in automotive applications!

LFP cells are what the Tesla Model 3 and Y RWD from GF Shanghai use. They'd be ideal for home batteries you'd think - I wonder when they'll switch the Powerwall.

From a technical standpoint that makes a lot of sense. I think the main obstacle there is that Tesla doesn't (as far as I know) actually make LFP batteries. The ones they use in their cars come from CATL. Tesla could just buy batteries from CATL and package them in a Powerwall product, but they might not be interested in doing that since there's a big risk that CATL or some other manufacturer could make an identical product without the Tesla brand and sell it at a much lower price.

There's a theory that Powerwall was just a way for Tesla to not waste their excess battery manufacturing capacity when car production wasn't keeping up. I don't know how true that is, but if so there isn't much of a need for them to figure out how to sell CATL's excess battery supply.

Re: CT scans of batteries

#56

Post by MobiusHorizons »

anon946 wrote: post #44
vitruvius wrote: post #2

The LG lithium ion cell that's second on this page is the one inside the Tesla Model Y battery pack.

That's interesting and somewhat surprising. I'm not knowledgeable about battery design by any means, but I would have thought that there would be a better way to make a battery pack for a car than connecting thousands of small batteries together.

This strategy is one of the remarked upon things when I first heard of Tesla (something like “this California startup is powering their electric car with laptop batteries”) ironically laptops have almost all transitioned to lithium polymer (pouch cells) instead of the 18650s they used back then. Not all car manufacturers use teslas standardized cell technique, as it does have some downsides. I guess time will tell, but I doubt Tesla will abandon this technique any time soon.

Re: CT scans of batteries

#57

Post by CarVac »

anon946 wrote: post #44
vitruvius wrote: post #2

The LG lithium ion cell that's second on this page is the one inside the Tesla Model Y battery pack.

That's interesting and somewhat surprising. I'm not knowledgeable about battery design by any means, but I would have thought that there would be a better way to make a battery pack for a car than connecting thousands of small batteries together.

Smaller cells are safer due to better containment of thermal runaway, letting them use a better-performing but somewhat riskier cell chemistry.

Re: CT scans of batteries

#58

Post by richk449 »

dsalzman wrote: post #6

The company behind these scans is https://www.lumafield.com/ - a really cool way to do marketing for your product. Love it!

Anyone know what energy the x-ray source is in their system? Seems really well designed, but if it doesn't have energy energy to penetrate the devices we need to scan, none of that will matter.

Re: CT scans of batteries

#60

Post by rbanffy »

ggm wrote: post #54
anon946 wrote: post #44

Earlier quoted context omitted.

That's interesting and somewhat surprising. I'm not knowledgeable about battery design by any means, but I would have thought that there would be a better way to make a battery pack for a car than connecting thousands of small batteries together.

if I remember my basic chemistry, batteries don't deliver voltages at the level of 10/20/100v directly often, its more commonly 1/2v or 0.5v class voltages. You have to have a much more 'aggressive' chemical reaction to deliver higher voltages. And, the same with current: a single surface between two reacting things delivers less current. Its a function of surface area. Same with capacitance: you sometimes need 'more…

> Inside a lead acid battery its multiple surfaces, sub-cells.

IIRC, “battery” used to be the technical term for “a bunch of connected power cells”.

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