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Comment by peterwwillis | Hacker News Reader

FYI: Tesla batteries are literally laptop batteries with cell balancing. No secret battery magic going on.

You could in theory crack open the pack and replace inefficient cells to get your capacity back. But, I'm assuming this is too huge a PITA for most people.

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I thought laptop batteries are also a bunch of phone batteries stuck together. Is that assumption incorrect?

Edit: apparently so.... I would appreciate a reply if anyone has time. I have a difficult time figuring out what about my question could have caused disagreement.

Not an expert and I didn't downvote but from my examination of laptop batteries, they appear to be composed of LIon cells of a standard size, something like 3V cells. Phone batteries OTOH seem to be pretty custom designs to fit a specific phone or range of phones. For e.g. https://electronics.stackexchange.com/questions/156928/repla...

Edit: added link.

Phone batteries are more commonly lithium polymer, and laptop batteries are more commonly lithium ion (using 18650 cells).

> No secret battery magic going on.

They have a complex cooling system. Your laptop battery definitely doesn't have that. If it did, it wouldn't need to be replaced every few years.

Most people need to replace their technology about as often as their batteries, so there is no incentive to cool them.

But the reasons they need to be replaced often is more about 1. Not keeping them at/above 40% charge, and 2. Laptop batteries don't balance the cells. Most laptop batteries can get 80% capacity back just by replacing one or two crap cells.

The "technology" involved here is #1 understating the raw capacity of the battery and #2 managing the charge/discharge levels and rates to maintain that capacity. This gives a good user experience and perception of longevity. Apple does the same thing with the iPhone and it makes the iPhone user experience noticeably better than comparable Android handsets where the charge controller just charges the battery as high and as fast as it can.

Essentially, this is good UX, but for battery charge indicators.

> Apple does the same thing with the iPhone and it makes the iPhone user experience noticeably better than comparable Android handsets where the charge controller just charges the battery as high and as fast as it can.

iPhone battery life and lifespan has been a much-hyped thing in certain circles for a while, so back when I got my first iPhone 5S, imagine my dismay to discover it was actually not noticeably different than my old HTC. Same with the 6.

What exact models are we comparing? HTC's current phones weigh more than the iPhone 6 and much more than the iPhone 5s. Note also that since Android follows the Windows/PC model, there exists hardware that does this correctly, and there exists hardware that does it incorrectly.

Sharing a form factor does not mean those two things are the same. The only similarity between laptop batteries and tesla batteries is the can they come in, which is... not important.

Please don't open a Tesla battery, the bus is at 600 volts and will kill you stone dead, then start a fire

The cells inside a Tesla S are off-the-shelf Panasonic catalog parts and are identical to parts found in some laptops (and flashlights, and so forth). Tesla's contributions are entirely in the controlling electronics, integration, cooling, etc.

That hasn't been true for a very long time. Tesla uses their own chemistry[1] and has put in extensive work improving it. One of the higher-profile changes was that they use 1-2% silicon (Musk mentioned this in a stockholder call), which panasonic still hasn't rolled out to the rest of their batteries.

[1]: https://electrek.co/2017/05/04/tesla-battery-researcher-chem...

I don't think those have ever been used in the model S.

Tesla has used a customized chemistry since just after the launch of the model S. Tesla literally has their name on the talk from that link. Do you think they're just doing research for fun?

I think people get confused because it's widely (and correctly) reported that Tesla uses 18650 cells. The confusion is that people think that's a model number, but it's actually just a size and shape. It's literally 18x65mm and the 0 means it's round. It tells you nothing at all about what's inside the cylinder.

NCR18650B is a specific series of parts from Panasonic(/Sanyo). If you want literally the exact battery that Tesla uses in the S, call Panasonic and tell them you want a shipment of ten million NCR18650BF (the new one with the silicon anode. The identity of these parts has been confirmed multiple times by people tearing down the battery packs (where they get this kind of disposable income, we don't know) and comparing the size/weight/discharge characteristics of single cells.

The "advanced chemistry" that Tesla moved to after a year of S production was a SiO-doped anode, exactly the difference between the B and BF part numbers from Panasonic-Sanyo. The cells weigh a gram less. This makes the charge density appear higher when the denominator is in terms of mass.

Tesla has done a wonderful job of selling their brand and convincing people that their batteries are other than off-the-shelf technology. In reality the same chemistry is available to anyone who calls up Panasonic and orders a hundred million batteries.

Do you have links? All I'm turning up with search terms like "NCR18650BF tesla teardown" are people using that as the closest point of comparison or speculating.

It's a PITA and also kind of dangerous.

Elon would personally come to your house and hit you with a stick.

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