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Comment by ip26 | Hacker News Reader

Same reason batteries in your phone or laptop are each a different shape and non-removable. They are an integral part of the design, a significant part of the weight & volume, with significant thermal concerns, etc... many electric cars today even use the battery as a "stressed member", aka the battery provides rigidity to the frame. How exactly will that be hotswappable in two minutes by John Doe?

Basically, the point is a standardized, easily removable, hotswappable widget makes a lot of sense when it's a minor item. But when it's half the weight, value, volume, and engineering challenge, you have to sacrifice all of those attributes to use the hotswap widget.

This originally made me think, if only we could pump fluid electrolyte in & out of the car, and let the battery take whatever form it likes. Then I realized that's called a flow battery, and then I realized that a hydrogen fuel cell is a type of flow battery.

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Most laptop batteries are standard lithium ion cells in a specially molded case.

While the 18650 Lithium Ion cell is a standardized shape, the chemistry between Lithium Ion implementations is different from company to company.

A big reason for Tesla's design was that Panasonic's Cells (a partner of Tesla) was superior on power-density / weight.

I expect that power-density / weight will continue to be an important factor in electric cars, especially when you need thousands of these cells to power an electric vehicle. As such, I don't expect lithium ion cells (even "standard" 18650 ones) to become a commodity.

How are they not literally already a commodity?

I get that you said that they each have their own chemistry, but are the owners of all of the chemistries choosing their customers?

Lets put it this way: how many battery packs actually reach 300-miles in practice?

Spoiler alert: Chevy Bolt is over 230 miles. Nissan Leaf is 150 miles. If you want 300 mile electric range, your only option is Panasonic (and by transitivity, Tesla, who is their only customer at the moment).

That feat alone means that Panasonic cells give you a real technological advantage. A Panasonic Li-Ion cell is worth far more than a typical Li-Ion cell. It is NOT a commodity, but a fundamental business advantage these days. If the other LiIon cell manufacturers manage to get real improvements to Power Density / weight, then maybe we can talk about Commodifying LiIon cells.

But for now, its Panasonic only.

My understanding is that there's very little demand for Tesla's chemistry (low cobalt NCA). All other automakers prefer NCM, primary because:

* better sustained performance compared to NCA

* better peak/burst performance compared to NCA

* easy to adjust formula to show preference for capacity, performance, or longevity (most automakers skip on the 3rd)

Tesla prefers NCA battery because:

* it has more capacity / weight

* it's much cheaper due to lower cobalt requirements (main reason)

The main reason traditional automakers tend to shy away from NCA because:

* it is far less stable than NCM, which puts it a much higher risk for fire or explosions

* it costs more than NCM to make stable (I suspect Tesla chem is cutting corners in this area)

You can decide whether the trade off of safety for range is worthwhile for you; traditional automakers err on the side of safety.

I've encountered many reports of issues with safety regarding autopilot or breakdown/less repairability of the vehicles due to lack of experience in design, but what evidence is there for Tesla cutting corners regarding battery safety specifically?

Just the choice of using NCA batteries over NCM could be viewed as a safety cost cutting measure.

Here's a scientific paper about the safety of various battery chemistries (warning, PDF): https://res.mdpi.com/wevj/wevj-06-00572/article_deploy/wevj-...

Summery is that, compared to NCM, NCA inhibits thermal runaway at much lower temperatures, offers significantly less short circuit resistance, slightly less overcharge buffer before thermal runaway, significantly faster thermal runaway after overcharge buffer is exhausted.

The result of thermal runaway is fire or explosion.

If you have the best product, you can pretty much choose your customers. But I suspect the choice is done simply with pricing to reflect better performance qnd or branding associated with it. Hence, counterfit cells are more common than real ones by top manufacturers. Even the pros are giving up trying to ID fakes and just focusing on testing whatever shows up in the box.

Ok, I guess I'm thinking of the "thin" family of laptops with molded flat packs. Or maybe those have standard flat cells, just not the 18650.

But in any case, technically even the Tesla just uses hordes of 18650. But that doesn't make it any easier to remove the pack itself.

I do wonder if cars based on sodium-sulfur fuel cells would behave well.

In principle they should be good (you just need some small battery to start them), but the problems of making them safe may overwhelm any gain you get from using fuel cells.

>>Same reason batteries in your phone or laptop are each a different shape and non-removable.

What? Most laptops on the market today have removable batteries, to the point where you can buy spare battery packs for them for long trips. Same with a lot of smartphones.

Unless of course you mean Apple products.

User-serviceable and removable are not the same.

There are few consumer laptops with removable (pops right out) batteries these days. I haven't seen one since the early 00s.

At best there are still those which are user-serviceable (requires a screwdriver and some finesse at the least). And Apple products where you cannot do even that.

Some business models still have the external removable battery, but have lower specs and higher price than consumer counterparts.

Almost no modern smartphones have removable batteries. It's rare enough that the LG G5 tried to make it a selling point a few years ago.

A lot of smart phones? Maybe I'm not a discerning enough Android fanboy, but none of my phones have had removable batteries:

* Nexus 4

* Nexus 5

* Nexus 6P

* Samsung Galaxy S7

* Samsung Galaxy S9

The only recent phones I was aware of with removable batteries were the LG G*, but I don't think the latest model of those has a removable battery anymore either.

Up until last year at least swappable batteries were still common in lower-end smartphones. Generally none of those OEMs sold spare batteries though; even when many high-end models had swappable batteries, up until 2015/2016-ish, almost no OEMs sold spare batteries. I think it was the beginning of 2016 that LG actually started selling spare batteries, the same year they produced their last two high-end smartphones with swappable batteries.

Even though swappable batteries do continue on the low-end, I think maybe [in the US] only Motorola actually makes spare batteries available for consumers to purchase, even for devices that don't have readily swappable batteries. I think this year Motorola will ditch swappable batteries, pretty sure, but will supposedly continue to make spares available for select models via Ifixit.

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